Micro-electro-mechanical device

Abstract

A microelectromechanical device (1) for capacitive fluid pressure measurement has a first electrode (2) and a second electrode (3) forming a counter electrode, the device (1) having a cavity (6) formed between a first delimiting layer (5a) and a second delimiting layer (5b) or a substrate (4), the first electrode (2) is arranged and is movably mounted in the cavity, the first and / or second delimiting layer (5a, 5b) can be displaced by a fluid pressure (p), the first and / or second delimiting layer (5a, 5b) being coupled to the first electrode (2) via a first coupling element (7a), and the first and / or second delimiting layer (5a, 5b) being coupled to the second electrode (2) via a second coupling element (7b). The invention relates to a device for transmitting a deflection movement to a movably mounted first electrode (2). The invention also relates to a micro-electro-mechanical pressure sensor, a micro-electro-mechanical microphone and a micro-electro-mechanical combined sensor element.

Description

Technical Field

[0001] The present invention relates to a micro-electromechanical device (also referred to as a MEMS device), a micro-electromechanical pressure sensor, a micro-electromechanical microphone and a micro-electromechanical combined sensor element. Background Art

[0002] A microelectromechanical device is known, for example, from US 2021 / 0 292 158 A1, which describes a MEMS microphone unit having a movable element and a measuring unit arranged in a cavity under negative pressure, wherein the movement of the movable element is mechanically transferred to the measuring unit.

[0003] DE 10 2021 206 005 A1 discloses a micromechanical component for a microphone device, which has an actuator electrode, a stator electrode and a sensor element, which is connected to the actuator electrode via a spring structure or a lever structure. The actuator electrode and the stator electrode can be arranged in a sealed cavity.

[0004] WO 2016 / 200538 A1 relates to an electromechanical device having a movable mirror which is held above a stationary electrode via a hinge and anchoring points.

[0005] CN 110621612 A describes a MEMS actuator device having a cavity and a movable element arranged in the cavity, which movable element can be driven via a potential between a first electrode and a further electrode.

[0006] WO 2016 / 067154 A1 discloses a MEMS display element having movable, light-reflecting electrodes. Summary of the invention

[0007] According to the present invention, a microelectromechanical device for capacitive fluid pressure measurement is proposed, the microelectromechanical device having a first electrode and a second electrode forming a counter electrode, wherein the device has a cavity formed between a first bounding layer and a second bounding layer or a substrate, the first electrode being arranged and movably supported in the cavity, wherein the first bounding layer and / or the second bounding layer can be displaced by fluid pressure, and wherein the first bounding layer and / or the second bounding layer is coupled to the first electrode via a first coupling element for transmitting the displacement movement to the first electrode movably supported.

[0008] Thus, a very compact micro-electromechanical device can be provided. Through the coupling of the movable boundary layer with the electrode arranged in the cavity in a movable manner, the direct transfer of the external offset movement to the electrode can be realized, the measuring mechanism is integrated into the cavity structure, and the device components are therefore concentrated in a small space protected from environmental influences. Advantageously, the encapsulated component does not have exposed movable parts and gaps, which may also be damaged due to external influences, such as attached particles, and thus hinder the function of the structural element. The following structural components of the device can be called cavity structures: the components limit the cavity or are arranged in the cavity. Through the cavity that is particularly fluid-tightly closed and has an integrated measuring mechanism, a very sensitive, particle-insensitive, fluid pressure measurement with a very good signal-to-noise ratio and a reduced fluid squeeze film damping effect can be achieved. Due to the compact configuration, the device can be constructed with particularly excellent performance under the same structural size, or can be constructed particularly small under the same required power. The cavity can have a predetermined gas pressure that is less than the ambient air pressure. In this way, thermal noise and squeeze film damping effects are effectively prohibited. The device may also have a plurality of cavities with the first electrode arranged therein, wherein the cavities may be encapsulated, ie may each be closed in a fluid-tight manner.

[0009] Depending on the selected embodiment, the cavity of the device can be formed between the first and second bounding layers of the device in a first variant, or between the first bounding layer of the device and the substrate in a second variant. In the first variant, the first and second bounding layers can be deflected by the fluid pressure acting on the first or second bounding layer. If the first and second bounding layers are mechanically coupled to each other, the first and second bounding layers can be deflected together by the fluid pressure acting on the first bounding layer or on the second bounding layer. In the second variant, the surface of the substrate can form the delimitation of the cavity at least in sections. The first bounding layer can be deflected by the fluid pressure acting on the first bounding layer.

[0010] For example, the first and / or second delimiting layer can be formed, for example, by a flexible or elastic diaphragm or a bending beam and can be reversibly displaced by a fluid pressure acting on the delimiting layer. The fluid pressure can be, for example, a static, quasi-static or dynamic fluid pressure and can also represent, for example, a mechanical fluid pressure vibration, such as an acoustic vibration, which causes a mechanical vibration of the delimiting layer. The first and / or second delimiting layer can be displaced, in particular steplessly displaced, between a static position or an initial position and a deflected position. Similarly, the first electrode can be displaced or tilted, in particular steplessly displaced or tilted, between a static position or an initial position and a deflected position. As will be explained below, the displaceability or tiltability can be understood in particular as a combination of a translational movement, a rotational movement and / or a deformation movement of at least a section.

[0011] The deflection movement transferred from the first and / or second delimiting layer to the first electrode by means of the first coupling element can be converted into an electrical signal by the resulting change in capacitance between the first electrode and the second electrode forming the counter electrode, so that the device can be referred to as an electromechanical converter. The first electrode and the counter electrode can form a measuring capacitance, by means of which a relative capacitance change relative to the initial capacitance can be detected and analyzed, wherein the capacitance change is related to the relative movement of the first electrode relative to the second electrode and the relative movement is in turn related to the deflection movement of the delimiting layer coupled to the first electrode. The coupling element can be used as a driver for the first electrode. By mechanically coupling the first electrode to the delimiting layer, a synchronous movement of the two components can be achieved and thus a direct conversion of the mechanical signal into an electrical signal can be achieved.

[0012] The first electrode is coupled to the first and / or second delimiting layer by means of a coupling element, which may have a length that substantially corresponds to the distance between the first electrode and the delimiting layer, and may have a width and a height or a diameter that extends perpendicularly to the length. The coupling element may also have a length that is smaller than the distance between the first electrode and the delimiting layer, so that mechanical support is not generated until a predefined external pressure value is reached. The coupling element may have a width and a height or a diameter that is smaller than the length, in particular a multiple of a smaller width and a height or a diameter, so that, for example, a narrow, rod-shaped or web-shaped coupling element is formed. The coupling element may extend transversely to, for example orthogonally to, the first electrode and the delimiting layer. The coupling element may cover the following electrode area of ​​the first electrode in the coupling point: the electrode area may be, for example, less than 10% of the entire electrode area, in particular less than 5% or 2% of the entire electrode area. Thus, the coupling of the electrode to the delimiting layer may be a substantially point-shaped coupling. The device may also have a plurality of first coupling elements, which couple the first electrode to the delimiting layer. In particular, the coupling element may be formed of an insulating material, so that the delimiting layer and the first electrode may be electrically insulated from each other.

[0013] The first electrode may have a capacitance measurement section that is substantially opposite to the capacitance measurement section of the second electrode so that the capacitance between the capacitance measurement sections can be detected. The first electrode and / or the second electrode may have another section that faces away from the capacitance measurement section. Depending on the embodiment, the coupling element may be arranged, for example, on the capacitance measurement section or away from the capacitance measurement section. The first and / or second electrode may have a perforation in a region facing away from the capacitance measurement section in order to maximize the ratio of the measured capacitance to the basic capacitance of the arrangement.

[0014] According to one embodiment, the second electrode can be arranged in the cavity. Thus, a compact and efficient measurement arrangement can be formed. The second electrode can be connected, for example, to the substrate or the body (Festland) of the device or to the lateral cavity boundary or can be incorporated into the lateral cavity boundary and protrude into the cavity. The second electrode can extend substantially parallel to the substrate surface or the substrate plane. If the second electrode is in an unshifted state, for example, in a static position, the second electrode can extend substantially parallel to the first electrode. The second electrode extends spaced apart from the first electrode to form a measurement capacitance together with the first electrode. For example, the first and second electrodes can be constructed as interdigital electrodes (Interdigitalelektrode), so that the first electrode and the measurement capacitance between the second electrode arranged in the cavity form a first measurement capacitance, and a 2f signal can be intercepted on the first measurement capacitance. This advantageously enables the measurement signal to be read out at a frequency double the excitation frequency. Since the noise is usually smaller at higher frequencies, a better signal-to-noise ratio for measurement is thus generated. The frequency doubling can be caused by an oscillating movement of the movable first electrode about the second electrode when the delimiting layer is deflected.

[0015] According to one embodiment, the second electrode can be supported in a movable manner, and wherein the first boundary layer and / or the second boundary layer are coupled to the second electrode via a second coupling element for transmitting the offset movement to the second electrode. Therefore, the second electrode can be supported in a movable manner like the first electrode. As a result, for example, a larger relative movement of the electrodes relative to each other can be achieved, and thus a stronger capacitance change can be caused. The second coupling element can be configured similarly or identically to the first coupling element in terms of its shape. By the type of the movable support, for example, the type of rotational mobility and / or translational mobility of the first electrode and the second electrode, different movement trajectories of the electrodes can be achieved and adapted to individual requirements and position conditions. For example, one of the two electrodes can be supported at least in sections in a manner that can be translated, and the other of the two electrodes can be supported at least in sections in a manner that can be tilted around a tilting axis, or the two electrodes can be tilted at different angles by lever arms of different lengths. The device can also have a plurality of second coupling elements, which couple the second electrode to the first and / or second boundary layer.

[0016] The movably supported electrode, for example the movably supported first electrode and / or the movably supported second electrode, can have at least one insulating stop. This can prevent the electrode from being welded or bonded to other structures of the device, for example the first and / or second delimiting layer, in the event of strong swings or overloads of the electrode. Alternatively or in addition, an insulating stop can also be provided on the first and / or second delimiting layer. The stop can increase the robustness of the cavity structure against overloads by reinforcing the delimiting layers in the event of contact and minimizing the contact surface.

[0017] According to one embodiment, the first coupling element and the second coupling element can be arranged on the first electrode and the second electrode in such a way that the first electrode and the second electrode can move in opposite directions to each other. As a result, a larger capacitance change and thus a stronger measurement signal can be caused. For example, the two electrodes can be tilted relative to each other around the corresponding tilting axis in different directions. For example, the first coupling element on the first electrode can be arranged away from the capacitance measuring section of the first electrode, and the second coupling element on the second electrode can be arranged on the capacitance measuring section of the second electrode, so that if the tilting axis of the first electrode is located between the capacitance measuring section and the coupling element, the second coupling element on the second electrode can cause a direct displacement of the capacitance measuring section, and the first coupling element on the first electrode can cause a displacement of the capacitance measuring section via a lever. As a result, the electrodes can be realized relative to each other, especially the capacitance measuring sections of the electrodes relative to each other. For example, the reverse movement of the electrodes can also mean a translational movement toward or away from each other.

[0018] The first electrode and / or the second electrode arranged in the cavity can be designed continuously or in segments. In the case of a segmented design of the electrode, there can be a plurality of spatially separated electrode segments of the same electrode, or in other words, a plurality of first electrodes and / or a plurality of second electrodes can be arranged in the cavity. This enables efficient use of the area of ​​the structural element.

[0019] According to one embodiment, the second electrode and / or the third electrode may be arranged in or on the first delimiting layer and / or arranged in or on the second delimiting layer, or formed by the first delimiting layer and / or the second delimiting layer. Therefore, for example, it is possible that the second electrode is not arranged in the cavity of the device, but is arranged in or on the first and / or second delimiting layer, or the second electrode is constructed by means of the first and / or second delimiting layer. In addition, it is possible to arrange the second electrode in the cavity of the device and the third electrode in or on the first and / or second delimiting layer, or the third electrode is constructed by means of the first and / or second delimiting layer. The second and third electrodes may form a counter electrode relative to the first electrode, respectively. In terms of terminology, here, the number of electrodes should not be specified by the ordinal number, but the arrangement possibility of the electrodes should be made clear. That is, the device may also have multiple first electrodes, multiple second electrodes and / or multiple third electrodes. Here, the first electrode is arranged in the cavity of the device. The second electrode may be arranged in the cavity or may be arranged in or on the first and / or second delimiting layer. If the second electrode is arranged in the cavity, the third electrode can be arranged in or on the first and / or second delimiting layer. The first electrode and the second or third electrode in or on the first and / or second delimiting layer can form a second measuring capacitance, on which a 1f signal can be intercepted. Thus, an additional or alternative measuring capacitance relative to the second measuring capacitance can be formed. The 1f signal is a measuring signal: the measuring frequency of the measuring signal corresponds to the excitation frequency. Therefore, in particular in combination with the first measuring capacitance that can be formed by the first electrode and the second electrode in the cavity of the device, multiple measuring capacitances in the device can be utilized, which, for example, allows differential capacitive measurement and generally allows high flexibility in measuring signal analysis and processing. The measuring signal, in particular the 1f measuring signal of the first measuring capacitance or the 2f measuring signal and the 1f signal of the second measuring capacitance, can be detected synchronously and can be calculated into the final measuring signal. In addition, it is possible to provide a pairing electrode in each of the two delimiting layers with the aid of two movable delimiting layers, so that similar to the above-mentioned embodiment, another additional measuring capacitance can be formed and detected synchronously.

[0020] According to one embodiment, the first electrode and / or the second electrode can be moved at least in sections in a translational manner by the displacement movement of the first and / or second limiting layer. Thus, the transfer of the displacement movement of the limiting layer to the first electrode and / or the second electrode can be achieved in a simple manner. For this purpose, the first electrode and the second electrode can be arranged, for example, in planes that overlap one another in the cavity. The first electrode and / or the second electrode can be moved in a translational manner together with the first and / or second limiting layer directly through the first and / or second coupling element. For example, the first electrode or a section of the first electrode can be moved relative to the fixed second electrode. Thus, a uniform capacitance change is caused between the capacitance measurement sections of the electrodes.

[0021] According to one embodiment, the first electrode and / or the second electrode can be tilted at least in sections around the tilting axis by the offset movement of the first boundary layer and / or the second boundary layer. Thus, the offset movement can be transferred to the first electrode and / or the second electrode in an efficient and space-saving manner. In particular, a lever mechanism can be realized by the tilting axis and the first coupling element of the first electrode and / or the second coupling element of the second electrode, by which a larger lever movement of the electrode can be generated by means of a small offset movement of the boundary layer. The lever mechanism can be, for example, a double-sided lever, the rotation point of which is formed by the tilting axis, the force arm of which is defined by the spacing between the coupling element and the tilting axis, and the load arm of the double-sided lever can have a capacitance measurement section of the electrode. It is also conceivable that the tilting axis is formed by the connection point of the electrode to the substrate or the body of the device. For example, the second electrode can protrude into the cavity from the substrate or the body of the device, for example from the lateral cavity boundary portion. Here, the second electrode can form a single-sided lever, which is implemented in a tiltable manner around the rotation point of the single-sided lever on the cavity boundary portion. According to another embodiment, the second electrode can also be designed as a double-sided lever according to the above description.

[0022] In other words, an electrode that can be tilted about a tilting axis can be an electrode that can be swiveled about a swivel axis. Tilt and swivel are understood to be rotation angles around a rotation axis, within which the rotational movement is limited. In particular, tilt and swivel are understood to be partial rotations that are less than a complete rotation, i.e., for example, less than 360° or 2π.

[0023] Depending on the configuration of the movable support of the electrode, a combination of translational mobility, rotational mobility and deformability is also conceivable. It is also possible, for example, for the first electrode to be designed in a translationally movable manner and the second electrode to be designed in a tilting manner, or vice versa. In particular, it can also be provided that the electrode is designed in a translationally movable manner in one or more sections of the electrode, in a tilting manner about a tilting axis in one or more other sections, and in a deformable manner in an intermediate section located therebetween, so that a combined translational mobility, rotational mobility and deformability of the electrode can be achieved. Deformability can be understood to mean, for example, elastic deformability of the electrode.

[0024] According to one embodiment, the tilting axis can be formed by a torsion spring. The torsion spring can be connected to the first electrode or constructed in one piece with the first electrode. The torsion spring can be connected to the second electrode or constructed in one piece with the second electrode. The torsion spring can be, for example, a beam or a tab that can be elastically twisted. The torsion spring can be attached to the substrate or the body of the device at one end or at both ends or to the lateral cavity boundary. Alternatively or additionally, the device can have a rigid frame that extends in the cavity and the torsion spring is attached to the rigid frame. Through the elastic torsionability of the torsion spring, the torsion spring can form a tilting axis for the electrode. The torsion spring can extend substantially perpendicular to the load arm and / or the force arm, for example substantially perpendicular to the capacitance measurement section of the electrode. Multiple electrodes or electrode beams of electrodes configured as interdigitated finger electrodes can also be attached to the torsion spring. The device can have multiple torsion springs, for example, a torsion spring for the first electrode and a torsion spring for the second electrode, or multiple torsion springs can also be provided for each electrode. The first and second electrodes can be connected in particular via a torsion spring or multiple torsion springs thereof and / or a rigid frame electrical contact. The length of the lever arm and thus the lever effect, i.e. the mechanical amplification of the movement, is adjusted by the position of the tilting axis. In addition, the self-resonance frequency of the device can be designed in a targeted manner in this way.

[0025] According to one embodiment, the first electrode and / or the second electrode can be tilted around a plurality of tilting axes spaced apart from each other. Thus, two or more sub-segments of the electrode that can be tilted in different ways, for example in opposite ways, can be realized on one electrode, for example. This can realize, for example, configuring a plurality of shorter lever arms, rather than a long lever arm with a very low self-resonance frequency, which increases the vibration robustness of the device. The tilting axis can be formed, for example, by a torsion spring, which is attached to the electrode spaced apart from each other. According to one embodiment, the number of the tilting axes can be an even number, for example two, four or six, so as to enable symmetrical, reverse tilting of the electrode. If a plurality of tilting axes are provided, the first electrode can be coupled to the first and / or second bounding layer via a plurality of first coupling elements and / or the second electrode can be coupled to the first and / or second bounding layer via a plurality of second coupling elements, so as to support the reverse tilting of the electrode segment and enable the stable, uniform tilting of the electrode segment.

[0026] According to one embodiment, the first coupling element can be arranged on a section of the first electrode facing the center of the cavity, and / or the second coupling element can be arranged on a section of the second electrode facing the center of the cavity. Thus, in the case of the translational mobility of the electrode, a uniform displacement of the electrode in the cavity can be achieved. In the case of the tiltability of the electrode around the tilting axis, if the coupling element acts on the section of the electrode facing the center of the cavity, it can be beneficial to the lever action of the electrode in the cavity around the tilting axis. For example, the capacitance measurement section of the electrode can be arranged on a section of the first electrode and / or the second electrode facing the lateral cavity delimiting portion, that is, away from the center of the cavity. The tilting movement can realize the small stroke of the delimiting layer to be optionally and mechanically converted into a larger stroke in the area of ​​the capacitance measurement section by a suitable ratio of the lever arm length. In a concentric arrangement, the displacement of the delimiting layer in the middle area of ​​the cavity can be greater than the displacement in the peripheral area of ​​the cavity attached to the substrate. As a result of this or also due to the fact that the cavity shape is mainly elongated parallel to the delimiting layer, depending on the embodiment, there may be less space for the electrode deflection in the middle area than in the peripheral area. Therefore, it may be beneficial and advantageous in terms of increased signal stroke to arrange the coupling of the electrode to the delimiting layer in an area of ​​the cavity that is smaller, i.e., in the middle area, for example, and to arrange the capacitance measurement section with high deflection in an area of ​​the cavity that is larger, i.e., in the peripheral area. The cavity center can be defined in terms of volume by the geometric center point of the cavity volume or in terms of area by the geometric center point of the cross-sectional plane of the cavity. For example, the spacing between the cavity center and the lateral cavity delimiting surfaces that are opposite to each other can be the same. In the case of a concentric arrangement, the cavity center can be located in the center of the concentric arrangement. Due to the mechanical properties of the delimiting layer, the deflection of the delimiting layer in the cavity center can be the highest, so that the lever arm can be advantageously placed here, while the capacitance change only occurs to a small extent in this area. In contrast, an outer region of the concentric arrangement, for example starting from half the radius of the concentric arrangement, constitutes for example 75% of the capacitive area of ​​the arrangement, so that the capacitive load arm of the lever can advantageously be placed in such an outer region.

[0027] According to one embodiment, the device may have a first delimiting layer and a second delimiting layer opposite the first delimiting layer, the second delimiting layer being arranged on the substrate side. The second delimiting layer may extend parallel to the first delimiting layer. The second delimiting layer may have a second and / or third electrode, the third electrode being configured as a counter electrode.

[0028] According to one embodiment, the device has a first and a second bounding layer, wherein a cavity is formed between the first and second bounding layers, and wherein the second bounding layer spans a substrate recess introduced into the substrate of the device, wherein the first and second bounding layers are mechanically connected to each other via a connecting element in such a way that the first and second bounding layers can be jointly deflected by a fluid pressure acting on the first and / or second bounding layers. In addition, collapse due to externally acting overpressure can be avoided thereby. By means of the synchronous, common mobility of the bounding layers connected to each other, the device can sense dynamic fluid pressures, such as sound waves, in an improved manner. The substrate recess can, for example, form a front volume and / or a back volume. The second bounding layer and the cavity of the device can span the substrate recess mainly or substantially completely. The substrate recess can include the entire extension of the substrate in a direction perpendicular to the main extension direction. Alternatively, the substrate recess can include only a portion of the extent of the substrate in a direction perpendicular to the main extension direction, wherein the recess can relate both to the portion facing the device and also to the portion facing away from the device.

[0029] The first and second delimiting layers are connected to each other by means of a connecting element, which can be used as a driver between the delimiting layers and as a stabilizer against an overpressure acting from the outside. The connecting element can have a length that corresponds essentially to the spacing between the delimiting layers, and a width and height or diameter extending perpendicularly to the length. The connecting element can also have a length that is smaller than the spacing between the delimiting layers, so that mechanical support is only generated after reaching a predefined external pressure value. The connecting element can have a width and height or diameter that is smaller than the length, especially a multiple of a smaller width, height or diameter, so that, for example, a narrow, rod-shaped or web-shaped connecting element is formed. The connecting element can extend transversely to, for example, orthogonally to the delimiting layers. The connecting element can cover the following connection area of ​​the delimiting layer in the coupling point: the connection area can be, for example, less than 10% of the entire delimiting layer area, especially less than 5% or 2% of the entire delimiting layer area. Therefore, the connection of the delimiting layers can be a basically point-shaped connection. The device can also have a plurality of connecting elements spaced apart from each other, which connect the first delimiting layer to the second delimiting layer. In particular, the connecting element can be formed from an insulating material, so that the two delimiting layers can be electrically insulated from one another.

[0030] According to one embodiment, the connecting element can be mechanically decoupled from the electrodes, so that the transfer of the deflection movement of the delimiting layer to the first and / or second electrode is only carried out in a targeted, point-like manner via the coupling element. The first electrode and / or the second electrode can have, for example, a recess or an intermediate space in the region of the connecting element, so that the connecting element can protrude through the first and / or second electrode or protrude next to the first and / or second electrode. According to another embodiment, the connecting element can be configured as a coupling element at the same time, for example, it can be attached to the delimiting layer and the first and / or second electrode, so that the electrode and the delimiting layer can be deflected together via a combined coupling connecting element.

[0031] The first electrode can be coupled to the first delimiting layer via the first coupling element and / or the second electrode can be coupled to the first delimiting layer via the second coupling element. Alternatively or additionally, it is possible that the first electrode is coupled to the second delimiting layer via the first coupling element and / or the second electrode is coupled to the second delimiting layer via the second coupling element.

[0032] According to one embodiment, the device may have a pressure balance channel, which extends through the first and second bounding layers and flows into the substrate recess. As a result, a defined quasi-static pressure balance can be achieved between the substrate recess and the environment. As a result, the measurement signal becomes independent of the pressure fluctuations of the environment. The pressure balance channel can extend substantially transversely to, in particular orthogonally to, the bounding layers. The first bounding layer may have a first pressure balance opening, the second bounding layer may have a second pressure balance opening, and the pressure balance channel extends between the first pressure balance opening and the second pressure balance opening. The pressure balance opening may be arranged, for example, substantially centrally in the bounding layers. The cross-sectional area of ​​the pressure balance channel perpendicular to its longitudinal extension between the bounding layers may be smaller than the cross-sectional area of ​​the first or second coupling element or connecting element perpendicular to its longitudinal extension between the bounding layers. The pressure balance channel may extend through the coupling element or be bounded laterally by the coupling element. The pressure balance channel can therefore be sealed airtightly relative to the cavity.

[0033] In principle, the first electrode and / or the second electrode and / or its capacitance measurement section can be configured as a planar plate electrode or a plurality of planar plate electrodes, for example. According to one embodiment, the first electrode and / or the second electrode can have a plurality of electrode beams, which extend substantially parallel to each other. Therefore, the first electrode and / or the second electrode can also be configured as a beam electrode or an interdigital finger electrode (Interdigital finger electrode). Such an electrode shape is accompanied by a high capacitance area density. In addition, compared with the planar electrode surface, the electrode beam can be movable due to its shape. The first electrode and / or the second electrode can have, for example, a rectangular planar electrode base surface, from which the electrode beam protrudes. By the defined arrangement of the planar electrode base surface and the electrode beam relative to each other, a more or less movable or more or less deformable region of the electrode can be pre-set in the cavity. The electrode beam can also protrude from the first and / or second limiting layer of the device, especially when the second electrode or the third electrode is arranged in the limiting layer or formed by the limiting layer. The first electrode and / or the second electrode may have a plurality of electrode base surfaces, between which electrode beams extend and to which the electrode beams are connected. In this embodiment, the electrode base surface may advantageously form a capacitance measurement section, because the electrode base surface may be approximately translated in the case of a tilting movement of the electrode beam and may therefore provide a defined and precise measurement signal. Depending on the embodiment, the first and / or second boundary layer may be coupled to the electrode base surface or to the electrode beams of the first and / or second electrode via a coupling element. Multiple or all electrode beams of the first and / or second boundary layer may also be coupled to the first and / or second boundary layer via a coupling element. In the intermediate space between the two electrode beams, the connecting element may extend between the first and second boundary layers. When an electrode is not deflected, the electrode beam of the electrode may, for example, extend substantially parallel to the first boundary layer. According to one embodiment, for example, the electrode beam of the second electrode may extend transversely to, for example, orthogonally to, the first boundary layer or transversely to, for example, orthogonally to, the first electrode that is not deflected, thereby enabling a compact electrode arrangement. Thus, depending on the embodiment, the electrode beam can extend, for example, horizontally or vertically in the cavity.

[0034] According to one embodiment, the electrode beam of the first electrode can be at least partially sunken into the middle space of the electrode beam of the second electrode. Alternatively or additionally, the electrode beam of the second electrode can be at least partially sunken into the middle space of the electrode beam of the first electrode. A compact electrode arrangement with a high capacitance area density is thereby achieved. For example, the capacitance measurement sections of the first and second electrodes can extend parallel to each other, at least in the undeflected state of the electrodes, so that the electrode beam of one electrode at least partially protrudes into the middle space of the electrode beam of the other electrode. In the event of a change in the position of at least one of the electrodes, for example in the event of a tipping of at least one electrode, the degree to which the electrode beam sinks into the middle space can be changed by the relative movement of the electrodes, thereby causing a significant capacitance change and causing a significant measurement signal associated therewith.

[0035] According to one embodiment, the device may have a plurality of first electrodes and / or one or more second electrodes, and the plurality of first electrodes and / or one or more second electrodes are arranged symmetrically about the cavity center in the cavity. For example, the first electrode and / or the second electrode or the plurality of second electrodes may be mirror-symmetrical or point-symmetrical relative to the cavity center. For example, the first electrode and / or the second electrode or the plurality of second electrodes may be arranged concentrically relative to the cavity center. For example, the first electrode and / or the second electrode or the plurality of second electrodes may be periodically arranged in the cavity. Through the aforementioned arrangement possibilities, an area-optimized and structural space-optimized arrangement of the electrodes with a high structural density may be achieved. For example, the cavity may have a rectangular cross-section, in which the first electrode and / or the second electrode or the plurality of second electrodes may be symmetrically, concentrically and / or periodically oriented relative to the cavity center of the cavity cross-section. The cavity center may be defined in relation to volume by the geometric center point of the cavity volume or in relation to area by the geometric center point of the cross-sectional plane of the cavity. The first electrode and / or the second electrode can, for example, form a common electrode group, wherein, for example, four electrode groups can be arranged at an angle of 90° to one another about a central axis extending through the center of the cavity and perpendicular to the delimiting layer. The first electrode and / or the second electrode or the second electrodes can have a symmetrical arrangement with respect to an axis of symmetry extending through the cavity or with respect to a symmetry point located in the center of the cavity. In the case of a symmetrical, concentric and / or periodic arrangement of the electrodes, the device can have a rigid, for example a cross-shaped frame, which extends through the cavity and can be attached to components such as torsion springs of the electrodes.

[0036] According to one embodiment, the device has a rigid frame, which divides the cavity into a plurality of sections, wherein a first electrode is arranged in each section, and the first electrode can be tilted at least in sections around a tilting axis defined by a torsion spring, wherein the torsion spring is connected to the rigid frame. Thus, an area-optimized and structural space-optimized arrangement of the electrode with a high structural density can be achieved. The rigid frame can extend through the cavity, for example, in a cross shape or in a star shape. The cavity can be divided into an even number or an odd number of sections by the rigid frame. According to one embodiment, the cavity can be divided into four sections, for example, by the rigid frame. The first electrode can be symmetrically oriented, for example, concentrically oriented and / or periodically arranged in the section about the cavity center. The capacitance measurement section of the first electrode in a section can face the cavity boundary. The first coupling element for coupling the first electrode to the first and / or second boundary layer can be arranged in a manner facing the cavity center. The first electrodes in the sections can be suspended on the rigid frame by springs, for example, torsion springs, respectively. Electrode recesses can be introduced in sections into the first electrode in order to reduce parasitic capacitances. Furthermore, between the electrode recesses, improved mobility of electrode regions of the first electrode is achieved, which can form, for example, electrode beams of the first electrode.

[0037] According to a configuration of the aforementioned embodiment, the second electrode and / or optionally the third electrode can be arranged in or on the first delimiting layer and / or in or on the second delimiting layer, or can be formed by the first delimiting layer and / or by the second delimiting layer, and can be segmented by one or more segment insulation parts so that an electrode segment of the second electrode and / or an electrode segment of the third electrode is assigned to a segment with a first electrode. As a result, a particularly accurate and segment-focused, low-parasitic detection of the capacitive measurement signal can be achieved, and in the case of three electrodes, a differential capacitive measurement signal can also be advantageously achieved. In other words, a capacitance measurement segment of each of the second electrode and the third electrode can be constructed between the two segment insulation parts of the second electrode, and the capacitance measurement segment is set up to form one or two measurement capacitors together with the capacitance measurement segment of the first electrode of the assigned segment.

[0038] According to one embodiment, the cavity can have a substantially circular or alternatively substantially rectangular cross section. This makes it possible to achieve an area-optimized and installation-space-optimized arrangement of the electrodes with a high installation density.

[0039] The structural components of the device described within the framework of the present application, such as the first electrode, the second electrode, the substrate, the delimiting layer, the coupling element, the connecting element, the rigid frame, the torsion spring and the further mentioned elements, can be made, for example, of silicon, metal (such as aluminum, titanium nitride or tungsten) and / or of silicon compounds or other semiconductor materials. The device can be produced by applying, structuring and etching material layers onto a substrate.

[0040] The micro-electromechanical device can be set up for sensing a fluid pressure or a fluid mass flow. For example, the micro-electromechanical device can be set up for a static or quasi-static absolute pressure measurement of an ambient pressure. In this case, the device can advantageously have a deflectable delimiting layer. The micro-electromechanical device can also be set up for a static, quasi-static or dynamic measurement of a relative pressure change, which is generated, for example, by acoustic vibrations. In this case, the device can advantageously have two mutually mechanically coupled, deflectable delimiting layers and a substrate recess.

[0041] The present invention also relates to a microelectromechanical pressure sensor, which has a microelectromechanical device according to any one of the aforementioned features and a signal processing unit, the signal processing unit being used to apply and process the signal of the microelectromechanical device. Thus, a very compact and high-performance pressure sensor can be provided, which has a very sensitive, particle-insensitive pressure measurement, a very good signal-to-noise ratio and a reduced fluid squeeze film damping effect. The pressure sensor can be set up in particular as an absolute pressure sensor or a relative pressure sensor for measuring static or quasi-static fluid pressure, such as the ambient pressure of the pressure sensor. The pressure sensor can have in particular one, according to one embodiment, exactly one bounding layer, which can be offset relative to the substrate of the device, and the bounding layer is coupled to the first electrode by a first coupling element for transferring the offset motion to the first electrode supported in a movable manner in the cavity between the substrate and the bounding layer. The microelectromechanical pressure sensor can be implemented, for example, as a system on a chip (SoC).

[0042] The invention also relates to a microelectromechanical microphone for capacitive sound pressure measurement, which has a microelectromechanical device according to any of the above-mentioned features and a signal processing unit, which is used to apply and process the signal of the microelectromechanical device. As a result, a very compact and high-performance microphone can be provided, which has a very sensitive, particle-insensitive pressure measurement, a very good signal-to-noise ratio and a reduced fluid squeeze film damping effect. The microphone can be a capacitive microphone, that is, an electroacoustic converter, which converts sound into a corresponding electrical signal in that the microphone detects a capacitance change caused by a change in the spacing between a first electrode and a second electrode that can move. The microphone can especially have a device of the above-mentioned type, which has a first bounding layer, a second bounding layer and a substrate recess adjacent to the second bounding layer, wherein the first bounding layer and the second bounding layer are mechanically connected to each other by a connecting element so that the first bounding layer and the second bounding layer can be deflected together by the fluid pressure acting on the first or second bounding layer. Due to the synchronous and common mobility of the bounding layers connected to each other, the device can sense sound waves in an improved manner. The substrate recess may, for example, form a front volume or a back volume.The micro-electro-mechanical microphone sensor may, for example, be implemented as a system on a chip (SoC).

[0043] The invention also relates to a micro-electromechanical combined sensor element, comprising a microphone for capacitive acoustic pressure measurement and / or an absolute pressure sensor and / or a relative pressure sensor, the combined sensor element having a micro-electromechanical device according to any of the aforementioned features and a signal processing unit for applying and processing the signal of the micro-electromechanical device. This can be achieved, for example, in that a first device having a substrate recess as a microphone is placed next to a second device having no substrate recess as an absolute pressure sensor on the same chip. As a result, a very compact combined sensor element with excellent performance can be provided.

[0044] Generally speaking, in the context of the present application, unless explicitly defined otherwise, the terms “a” and “an” are not to be understood as numerals, but as indefinite articles having the meaning of “at least one”. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The present invention allows for different embodiments and is explained in more detail below based on an example with the aid of the attached drawings. The drawings show in a schematic manner:

[0046] Figure 1a-1b - a cross-sectional top view and a cross-sectional side view of the microelectromechanical device according to the first embodiment;

[0047] Figure 2a-2c a cross-sectional top view and two cross-sectional side views of a microelectromechanical device according to a second embodiment;

[0048] Figure 3a-3b - a cross-sectional top view and a cross-sectional side view of a microelectromechanical device according to a third embodiment;

[0049] Figure 4a-4b - a cross-sectional top view and a cross-sectional side view of a micro-electromechanical device according to a fourth embodiment;

[0050] Figure 5a-5c a cross-sectional top view, a cross-sectional side view and a further cross-sectional top view of two variants of a microelectromechanical device according to a fifth embodiment;

[0051] Figure 6a-6b - a cross-sectional top view and a cross-sectional side view of a microelectromechanical device according to a sixth embodiment;

[0052] Figure 7a-7b - a cross-sectional top view and a cross-sectional side view of a microelectromechanical device according to a seventh embodiment;

[0053] Figure 8a-8c - two cross-sectional top views and a cross-sectional side view of a microelectromechanical device according to an eighth embodiment;

[0054] Fig. 9 ——Schematic diagram of a microelectromechanical pressure sensor with a microelectromechanical device. DETAILED DESCRIPTION

[0055] Figure 1a and 1b A micro-electromechanical device 1 according to a first embodiment is shown. Figure 1a shows a cross-sectional top view of the device 1, Figure 1b A cross-sectional side view of the device 1 is shown. The microelectromechanical device 1 is set up for capacitive measurement of a fluid pressure or a fluid mass flow. For this purpose, the device 1 has a first electrode 2 and a second electrode 3, which can be planar surface electrodes, as shown. The device 1 has a substrate 4 and a first bounding layer 5a, which extends spaced apart from the substrate 4. The first bounding layer 5a is designed as an elastically deflectable diaphragm and can extend essentially parallel to a substrate surface or a substrate plane of the substrate 4 in an undeflected state. Figure 1b , the first delimiting layer 5a is shown in a deflected state, wherein the rest position of the first delimiting layer 5a in the non-deflected state is indicated by a dot-dashed line. As shown in the figure, the deflection of the first delimiting layer 5a can be caused by an external fluid pressure p acting on the first delimiting layer 5a. As mentioned above, the third electrode 20 can be arranged in or on the first delimiting layer 5a, or can be formed by the first delimiting layer.

[0056] A cavity 6 is formed in the device 1, which is bounded by the substrate 4, the first delimiting layer 5a and the lateral cavity delimitation L ( Figure 1a The cavity 6 is delimited by the dotted line in FIG. 1 . The cavity 6 can be closed in a fluid-tight manner. Advantageously, a gas volume can be contained in the cavity 6, which has a gas pressure that is lower than that of the ambient air. The cavity 6 has a cavity center M defined geometrically in the center of the cavity 6. The first electrode 2 and the second electrode 3 are arranged in the cavity 6. According to the embodiment shown, the second electrode 3 is configured as a fixed electrode 4, while the first electrode 2 is supported in a movable manner. In this case, Figure 1b It can be seen that the first electrode 2 can be tilted about two tilting axes 8 by means of a displacement movement of the first delimiting layer 5a, whereby the displacement movement can be transferred to the first electrode 2 in a space-saving manner. The tilting axis 8 is formed by an elastically torsionable torsion spring which is connected to the first electrode 2 on the one hand and to the cavity delimiting portion L of the device 1 on the other hand. As shown in the figure, by means of two tilting axes 8 spaced apart from each other, subsections of the first electrode 2 can be tilted in opposite directions to each other. Figure 1b , the first electrode 2 is shown in a deflected state, wherein the rest position of the electrode 2 in the non-deflected state is indicated by a dot-dashed line. The first electrode 2 is mechanically coupled to the first delimiting layer 5a via a plurality of first coupling elements 7a. As a result, the deflection movement of the first delimiting layer 5a can be transferred to the first electrode 2, so that the first electrode 2 performs a relative movement relative to the second electrode 3 by tilting and causes a measurable capacitance change relative to the initial capacitance. The capacitance change can be detected as an electrical signal, which is related to the deflection movement of the first delimiting layer 5a. At the same time, a further capacitance change between the first electrode 2 and the third electrode 20 can be detected as a signal, and the differential signal can be formed as a measurement variable for pressure.

[0057] The device 1 has a very compact measuring mechanism. By coupling the deflectable first delimiting layer 5a with the first electrode 2, a direct transfer of the deflection movement via the cavity structure of the device 1 is achieved, and the measuring mechanism of the device 1 is thus concentrated in a minimal space. With the measuring mechanism integrated into the cavity 6 of the device 1, a sensitive, particle-insensitive capacitive pressure measurement with a very good signal-to-noise ratio can be achieved.

[0058] According to the schematically shown embodiment, the first coupling element 7a is designed in the form of a web and has a width and height that are smaller than the length, wherein the length can be defined essentially by the distance between the coupling point of the first coupling element 7a to the first electrode 2 and the coupling point to the first delimiting layer 5a. As a result, an essentially point-shaped coupling of the first electrode 2 to the first delimiting layer 5a can be achieved. The first coupling element 7a extends essentially perpendicularly to the first electrode 2 and the delimiting layer 5.

[0059] exist Figure 1a and 1b The device 1 shown in the figure can be used, for example, as a capacitive measuring device for an absolute pressure sensor. In this case, the fluid pressure p can be, for example, a static or quasi-static ambient fluid pressure, and the device 1 can be set up to measure absolute pressure values. In the following embodiments, the fluid pressure p can also be, for example, a dynamic fluid pressure, and the device 1 can be set up to measure relative pressure changes, so that the device 1 can also be used as a capacitive measuring device for a microphone.

[0060] Figure 2a , 2b 2 c show a micro-electromechanical device 1 according to a second embodiment. Figure 2a shows a cross-sectional top view of the device 1 in the non-deflected state of the first delimiting layer 5 a, Figure 2b shows a cross-sectional side view of the device 1 in the undeflected state of the first delimiting layer 5a, and Figure 2c 1 shows a cross-sectional view of the device 1 in a state in which the first limiting layer 5a is deflected by the fluid pressure p. The microelectromechanical device 1 is designed for capacitive measurement of a fluid pressure or a fluid mass flow, in particular a dynamic one, for example for detecting acoustic vibrations. For this purpose, the device 1 has a first electrode 2 and a second electrode 3, such as Figure 2a As shown, the first electrode and the second electrode can be finger electrodes or beam electrodes. Here, the first electrode 2 has a plurality of electrode beams 2b extending parallel to each other and protruding from the planar electrode base surface 2a. In addition, the second electrode 3 has a plurality of electrode beams 3b extending parallel to each other and protruding from the planar electrode base surface 3a. The electrode beams 2b of the first electrode 2 and the electrode beams 3b of the second electrode 3 extend substantially parallel to the limiting layers 5a, 5b.

[0061] The device 1 has a first delimiting layer 5a and a second delimiting layer 5b opposite to the first delimiting layer 5a, which is arranged on the substrate side. According to the illustrated embodiment, the delimiting layers 5a, 5b are constructed as elastically deflectable membranes. The first delimiting layer 5a and the second delimiting layer 5b extend substantially parallel to each other, especially in an undeflected state. The substrate recess 9 is introduced into the substrate 4 in a manner adjacent to the second delimiting layer 5b. The second delimiting layer 5b spans the substrate recess 9. A cavity 6 is formed between the first delimiting layer 5a and the second delimiting layer 5b, in which the first electrode 2 is supported in a movable manner and the second electrode 4 is fixedly arranged. The cavity 6 is additionally delimited between the delimiting layers 5a, 5b by a body (Festland) 19 and a lateral cavity delimitation L of the body 19.

[0062] The first delimiting layer 5a and the second delimiting layer 5b are connected to one another via the connecting element 10 and can therefore be displaced jointly and synchronously by the fluid pressure p acting on the first or second delimiting layer 5a, 5b. Figure 2b The undeflected state, ie the rest position of the delimiting layers 5a, 5b, is shown in FIG. Figure 2c , the limiting layers 5a, 5b are shown in a deflected state, wherein the corresponding static positions of the limiting layers 5a, 5b are indicated by dotted lines. As shown in the figure, the deflection of the first limiting layer 5a can be caused by an external fluid pressure p acting on the first limiting layer 5a. According to the schematically shown embodiment, the connecting element 10 is constructed in a web-shaped manner and has a width and height that are smaller than the length, wherein the length can be basically defined by the spacing between the limiting layers 5a, 5b. As a result, a basically point-shaped connection between the limiting layers 5a, 5b can be achieved. The connecting element 10 extends basically perpendicular to the limiting layers 5a, 5b. According to the shown embodiment, the connecting element 10 is mechanically decoupled from the electrodes 2, 3, and only the limiting layers 5a, 5b are connected to each other. For this purpose, for example, as shown in the figure, the connecting element 10 is arranged in the intermediate space between the electrode beams 2a of the first electrode 2 and protrudes through between the electrode beams 2a.

[0063] The cavity 6 can be closed in a fluid-tight manner. Advantageously, a gas volume can be included in the cavity 6, which has a gas pressure that is less than that of the ambient air. The cavity 6 has a geometrically defined cavity center M in the center of the cavity 6. The first electrode 2 and the second electrode 3 are arranged in the cavity 6. The second electrode 3 is incorporated into the cavity delimitation portion L by means of an electrode base surface 3a, from which the electrode beam 3b of the second electrode 3 protrudes into the cavity 6 in the direction of the cavity center M. The second electrode 3 extends essentially parallel to a substrate plane of the substrate 4, wherein the substrate plane can be defined by the largest planar extension of the substrate 4. According to the illustrated embodiment, the second electrode 3 is configured as a fixed electrode 4, while the first electrode 2 is supported in a movably manner. Here, from Figure 2cIt can be seen from the figure that the first electrode 2 can be tilted about two tilting axes 8 by the deflection movement of the delimiting layers 5a, 5b, whereby the deflection movement can be transferred to the first electrode 2 in a space-saving manner. The tilting axis 8 is formed by an elastically torsionable torsion spring, which is connected to the electrode beam 2b of the first electrode 2 on the one hand and to the transverse cavity delimitation L of the device 1 on the other hand. As shown in the figure, the subsections of the first electrode 2 can be tilted in opposite directions to each other by two tilting axes 8 spaced apart from each other. The first electrode 3 is mechanically coupled to the first delimiting layer 5a and the second delimiting layer 5b by a plurality of first coupling elements 7a. As a result, the deflection movement of the delimiting layers 5a, 5b can be transferred to the first electrode 2, so that the first electrode 2 performs a relative movement relative to the second electrode 3 by tilting and can cause a measurable capacitance change relative to the initial capacitance. The capacitance change can be detected as an electrical signal, which is related to the deflection movement of the delimiting layers 5a, 5b.

[0064] By means of the tilting axis 8 of the first electrode 1 and the first coupling element 7a, a lever mechanism can be realized, by means of which a larger tilting movement of the first electrode 1 can be generated by means of a small deflection movement of the delimiting layers 5a, 5b. Figure 2a As shown, the lever mechanism can be a double-sided lever, the rotation point of which is formed by the tilting axis 8. The lever arm 13 is defined by the distance between the coupling element 7a and the tilting axis 8, while the load arm 14 is formed by the section of the first electrode 2 opposite the lever arm 13. As shown in the figure, the lever arm 13 can be shorter than the load arm 14, so that a high signal stroke can be achieved in the load arm 14 by means of a small deflection movement of the lever arm 13.

[0065] like Figure 2a As shown, the first electrode 2 can have a first capacitance measuring section 15a, which is substantially opposite to the second capacitance measuring section of the second electrode 3, so that the capacitance between the capacitance measuring sections 15a, 15b can be detected. In this case, the electrode beam 2b of the first electrode 2 is partially immersed in the intermediate space of the electrode beam 3b of the second electrode 3, and vice versa, wherein, as according to Figure 2b and 2c As shown, the degree of sinking changes during the tilting movement of the first electrode 2, because the electrode beam 2b of the first electrode 2 is partially tilted out of the plane of the electrode beam 3b of the second electrode 3. According to the schematic diagram, the coupling element 7a of the first electrode 2 is arranged on the section of the first electrode 2 facing away from the capacitance measuring section 15a of the first electrode 2. In this case, the capacitance measuring section 15a of the first electrode 2 can be assigned to the previously described capacitance measuring section 15a. Figure 2aThe load arm 14 of the illustrated lever. The first coupling element 7a is arranged on the section of the first electrode 2 facing the cavity center M, while the capacitance measuring section 15a of the first electrode 2 is arranged on the section of the first electrode 2 facing the lateral cavity boundary L.

[0066] The first electrode 2 forms together with the second electrode 3 a first measuring capacitance, at which a 2f signal can be tapped. Optionally, by arranging a third electrode 20 or a plurality of third electrodes 20 as one or more planar additional counter electrodes in or on one or both of the delimiting layers 5a, 5b in a manner not shown in more detail, at least one additional measuring capacitance can be formed together with the first electrode 2, at which a 1f signal can be tapped. Advantageously, the 2f measuring signal of the first measuring capacitance and the 1f signal of the second measuring capacitance can be detected synchronously and can be calculated into a final measuring signal. Also not shown in more detail is that the first electrode 2 can have at least one insulating stop in order to prevent the electrode 2 from welding to the surrounding structure in the event of an overload. For example, such a stop can be arranged on a tiltable electrode beam or delimiting layers 5a, 5b of the first electrode 2.

[0067] The device 1 has a very compact measuring mechanism. By coupling the deflectable delimiting layers 5a, 5b to the first electrode 2, a direct transfer of the deflection movement via the cavity structure of the device 1 is achieved, and the measuring mechanism of the device 1 is thus concentrated in a minimal space. With the measuring mechanism integrated into the cavity 6 of the device 1, a sensitive, particle-insensitive capacitive pressure measurement with a very good signal-to-noise ratio can be achieved.

[0068] According to the schematically shown embodiment, the first coupling element 7a is constructed in a web-shaped manner and has a width and height that are smaller than the length, wherein the length can be substantially defined by the spacing between the first delimiting layer 5a and the second delimiting layer 5b. As a result, a substantially point-shaped coupling of the first electrode 2 with the delimiting layers 5a, 5b can be achieved. The first coupling element 7a extends substantially perpendicularly to the first electrode 2 and the delimiting layers 5a, 5b. In this embodiment, advantageously, as shown in the figure, the coupling element 7a is arranged on the planar electrode base surface 2a of the first electrode 2. As a result, a uniform and stable deflection of the electrode 2 on the electrode base surface 2a can be achieved by the coupling element 7a, while the electrode beam 2b can be slightly tilted around the tilting axis 8.

[0069] according to Figure 2a-2c, a pressure equalization channel 11 extends between the first limiting layer 5a and the second limiting layer 5b, and the pressure equalization channel opens into the substrate recess 9. As a result, a defined quasi-static pressure balance can be achieved between the substrate recess 9 and the environment. In the embodiment shown, the pressure equalization channel 11 extends substantially through the cavity center M and through the first coupling element 7a.

[0070] Figure 3a and 3b A micro-electromechanical device 1 according to a third embodiment is shown. Figure 3a shows a cross-sectional top view of the device 1 in the deflected state of the delimiting layers 5 a, 5 b, Figure 3b A cross-sectional side view of the device 1 in the deflected state of the delimiting layers 5a, 5b is shown. The device 1 shown is similar to the device 1 according to the second embodiment in terms of its basic structure and functional principle. In the device 1 according to the third embodiment, the first electrode 2 has another tilting axis 8, in this case a total of four tilting axes 8. As a result, the first electrode 2 has a plurality of subsections, which can be tilted in opposite directions around the tilting axis 8, and the subsections form a plurality of shorter lever arms with a higher self-resonant frequency. The tilting axis 8 is arranged symmetrically with respect to the cavity center M and substantially perpendicular to the electrode beam 2b. The tilting axis 8 is constructed as a torsion spring and is fastened to the cavity delimiting portion L of the device 1. In this embodiment, the first electrode 2 has a plurality of electrode base surfaces 2a, between which the electrode beam 2b extends. As a result, the stability of the electrode 2 can be improved and a defined deflection of the electrode beam 2b can be achieved. On the outer electrode base surface 2a of the first electrode 2 and on the middle electrode base surface 2a, a first coupling element 7a is provided for coupling the first electrode 2 to the limiting layers 5a, 5b, while the electrode base surface 2a arranged between the outer and middle electrode base surfaces 2a does not have a coupling element 7a. Advantageously, these electrode base surfaces 2a can form capacitance measurement sections 15a, because in the case of a tilting movement of the electrode beam 2b, these capacitance measurement sections can be moved almost translationally toward the second electrode 3 or away from the second electrode. As a result, a very precise measurement signal can be generated. In a third embodiment, as Figure 3b As shown, the second electrode 3 is formed by the delimiting layers 5 a and / or 5 b .

[0071] Figure 4a and 4b A micro-electromechanical device 1 according to a fourth embodiment is shown. Figure 4a shows a cross-sectional top view of the device 1 in the deflected state of the delimiting layers 5 a, 5 b, Figure 4bA cross-sectional side view of the device 1 is shown in the deflected state of the delimiting layers 5a, 5b. The device 1 shown is similar to the device 1 according to the third embodiment in terms of its basic construction and functional principle, for example, the device 1 has a plurality of, here four, tilting axes 8. However, in the device 1 according to the fourth embodiment, the electrode base 2a is also tilted about the tilting axis 8. In addition, the electrode beams 3b of the second electrode 3 protrude vertically into the cavity 6 from the first and second delimiting layers 5a, 5b toward the first electrode 2. The vertical electrode beams 3b extend substantially perpendicularly to the delimiting layers 5a, 5b. As a result, a compact electrode arrangement with a high capacitance area density can be achieved. The connecting element 10 extends between the vertically arranged electrode beams 3b of the second electrode 3 and between the electrode bases 2a of the first electrode 2 for connecting the delimiting layers 5a, 5b to each other. In the region of the cavity center M and at the outer end section of the first electrode 2 facing the cavity delimitation L, a first coupling element 7a is arranged, which couples the first electrode 2 to the delimiting layers 5a, 5b. Figure 4a As shown, in this embodiment, the first coupling element 7a at the end section of the first electrode 2 is not configured as a tab-shaped coupling element 7a, but as a bridge structure extending over the entire width of the electrode 2. As a result, an advantageous force transmission to the electrode 2 can be achieved. Figure 4a As becomes clear, the device 1 according to the fourth specific embodiment has a high structural density due to its compact electrode arrangement, so that there is a high area utilization of the micromechanical components.

[0072] Figures 5a to 5c A device 1 according to a fifth embodiment is shown, wherein Figure 5a A first variant with a rectangular cavity is shown, Figure 5b , c shows a second variant of the fifth embodiment with a circular cavity. In the fifth embodiment, the device 1 has a rigid frame 12, which divides the cavity 6 into sections, wherein a first electrode 2 is arranged in each section 22, which can be tilted at least in sections about a tilting axis 8 defined by a torsion spring, wherein the torsion spring is attached to the rigid frame 12. The rigid frame 12 is in turn anchored to the transverse cavity delimitation L on the body 19.

[0073] For example, Figure 5aIn a cross-sectional top view, a device 1 according to a fifth embodiment is shown, which has a rectangular cross section of a cavity 6, in which the cavity structure, in particular the first electrode 2 and the second electrode 3 of the device 1, are oriented symmetrically and concentrically with respect to the cavity center M. The first electrode 2 and the second electrode 3 form four electrode groups, which are each twisted at an angle of 90° relative to each other about the cavity center M. A rigid frame 12 is arranged in the cavity 6 and is fastened to the cavity delimitation L of the device 1. The rigid frame 12, which is shown in a cross shape here, divides the cavity into four sections (22), in which the electrode groups are arranged, wherein the rigid frame 12 has a subframe around the cavity center M and a pressure compensation channel 11 that is mechanically decoupled from the rigid frame 12. A first part of the first electrode 2 in each section extends parallel to the rigid frame 12, which first part has two electrode beams 2b extending at an angle to each other, which are in turn connected by further electrode beams 2b extending between the electrode beams 2b as cross braces. Between the cross struts, the electrode beams 3b of the second electrode 3 extend as vertically arranged electrode beams below and / or above the first electrode 2, similarly to the fourth embodiment. The tilting axis 8, which is designed as a torsion spring, extends parallel to the cavity delimitation of the cavity 6 and forms a rectangle on all four sections 22, in the corners of which the torsion springs are attached to the rigid frame 12. At the corners of the electrode beams 2b of the first electrode 2 extending at an angle to each other, a first coupling element 7a is arranged, which connects the first electrode 2 to the delimiting layers 5a, 5b. Between the rigid frame 12 and the electrode beams 2b of the first electrode 2 extending at an angle to each other, and in the region of the electrode beams 3b of the second electrode 3, connecting elements 10 are arranged, which connect the delimiting layers 5a, 5b to each other. In order to explain the structure of the fifth embodiment, the following assumption can be made: the fluid pressure p acts in the plane of the paper and acts on the coupling element 7a. The electrode beam 2b extending at an angle toward the coupling element 7a is simultaneously pressed downward into the plane of the paper as far as the tilting axis 8, but at the same time it is pivoted out of the plane of the paper via its tilting axis 8 in the region between its vertical electrode beams 3b of the second electrode 3, so that a capacitance change is produced here between the finger electrodes 2b, 3b. The device 1 according to the fifth embodiment enables a very advantageous utilization of the area.

[0074] Figure 5b and 5cA cross-sectional side view and a cross-sectional top view of a device 1 having a circular cross-section of a cavity 6 are shown. The device 1 has a rigid, here cross-shaped extending frame 12, which here divides the cavity 6 into four sections 22. A subframe of the rigid frame 11 is constructed around a mechanically decoupled pressure equalization channel 11. A first electrode 2 is arranged in each section 22. The first electrode 2 has an electrode recess 24 in order to reduce parasitic capacitance. The electrode area formed between the electrode recesses 24 forms an electrode beam 2b of the first electrode 2. The first electrode 2 in each section 22 can be tilted at least in sections around a tilting axis 8 defined by a torsion spring, wherein the torsion spring is attached to the rigid frame 12. The first electrode 2 is oriented symmetrically, here concentrically, relative to the cavity center M and is periodically arranged in the sections 22. The capacitive section 15a of the first electrode 2 faces the cavity delimitation portion L. The first coupling element 7a of the first electrode 2 faces the cavity center M. As shown Figure 5b As shown, the second electrode 3 is constructed in the first delimiting layer 5a, the third electrode 20 is constructed in the second delimiting layer 5b, and is segmented by a plurality of segment insulations 21, wherein the electrode segment 23 of the second electrode 3 and the electrode segment 25 of the third electrode 20 are assigned to the segment 22 having the first electrode 22. In other words, between the two segment insulations 21 of the second electrode 3 and the third electrode 20, a capacitance measuring segment 15b of the second electrode 3 and a capacitance measuring segment 15c of the third electrode 20 are constructed, which are designed to form two measuring capacitances together with the capacitance measuring segment 15a of the first electrode 2 of the assigned segment 22. The delimiting layers 5a, 5b are coupled to each other by the connecting element 10 and can be deflected together. By means of the first coupling element 7a, the first electrode 2 can be deflected together with the delimiting layers 5a, 5b and tilted about the tilting axis 8.

[0075] Figure 6a and 6b A micro-electromechanical device 1 according to a sixth embodiment is shown. Figure 6a shows a cross-sectional top view of the device 1 in the deflected state of the delimiting layers 5 a, 5 b, Figure 6b 1 shows a cross-sectional side view of the device 1 in the deflected state of the delimiting layers 5a, 5b. The device 1 shown is similar to the device 1 according to the second embodiment in terms of its basic design and functional principle. In the device 1 according to the sixth embodiment, the second electrode 3 is also supported in a movable manner and coupled to the delimiting layers 5a, 5b via the second coupling element 7b. Thus, as in Figure 6bAs shown in the schematic diagram according to the arrows, the first electrode 2 and the second electrode 3 can be tilted in opposite directions to each other, so as to achieve a larger relative movement of the first and second electrodes 2, 3 and thus cause a stronger measurement signal. According to the embodiment shown, the second electrode 3 forms a one-sided lever, which can be tilted around the tilting axis 8 on the lateral cavity boundary L. As shown in the figure, the second electrode 3 can be displaced directly on its capacitance measuring section 15b, while the capacitance measuring section 15a of the first electrode 2 can be displaced via the double-sided lever about the tilting axis 8, so that the opposite movement can be generated. In addition, in the sixth embodiment, the coupling elements 7a, 7b are simultaneously configured as connecting elements 10, so that the coupling elements 7a, 7b connect the boundary layers 5a, 5b to each other and connect these boundary layers to the first and second electrodes 2, 3.

[0076] Figure 7a and 7b A micro-electromechanical device 1 according to a seventh embodiment is shown. Figure 7a shows a cross-sectional top view of the device 1 in the deflected state of the delimiting layers 5 a, 5 b, Figure 7b A cross-sectional side view of the device 1 is shown in the deflected state of the delimiting layers 5a, 5b. The device 1 shown is similar to the device 1 according to the sixth embodiment in terms of its basic structure and functional principle. However, the device 1 according to the sixth embodiment shows a continuous first and second electrode 2, 3, while the device 1 according to the seventh embodiment has a segmented first and second electrode 2, 3, that is, the first and second electrodes 2, 3 have electrode segments that are spatially separated from each other and are not directly connected to each other. As a result, an improved area utilization can be achieved with the help of short lever arms on the first and second electrodes 2, 3. According to the embodiment shown, the electrode segments separated from each other are respectively attached to the cavity delimiting portion L of the device 1 via a torsion spring and are coupled to the first delimiting layer 5a via coupling elements 7a, 7b, which also form the tilting axis 8 of each electrode segment.

[0077] Figures 8a to 8c FIG. 8 shows a cross-sectional view in a first plane of the device in a deflected state of the delimiting layers 5 a , 5 b , Figure 8b shows a cross-sectional top view in a second plane of the device 1 in the deflected state of the delimiting layers 5a, 5b, and Figure 8cA cross-sectional side view of the device 1 is shown in a deflected state of the delimiting layers 5a, 5b. In this electrode arrangement, the first electrode 2 and the second electrode 3 are arranged in planes that are superimposed on one another in the cavity 6, for example, as shown in the figure, the first electrode 2 is arranged closer to the first delimiting layer 5a and the second electrode 3 is arranged closer to the second delimiting layer 5b. The first and second electrodes 2, 3 have electrode bases 2a, 3a that are superimposed on one another and electrode beams 2b, 3b that protrude therefrom, which are coupled to at least one of the two delimiting layers 5a, 5b via coupling elements 7a, 7b, respectively, and can be tilted about a tilting axis 8. By tilting the electrode beams 2b, 3b of the electrodes 2, 3, a translational movement of the electrode bases 2a, 3a relative to one another is caused, so that the capacitance change can be accurately measured.

[0078] Fig. 9 A microelectromechanical structure element 16 is schematically shown, which has a device 1 according to the above features and a signal processing unit 17, which is connected to the device 1 via a signal connection 18 and is designed to apply and process the signals of the microelectromechanical device 1. The microelectromechanical structure element 16 can be designed in particular as an absolute pressure sensor and / or a relative pressure sensor and / or a microphone. The microelectromechanical structure element 16 can be implemented as a system on a chip, for example.

Claims

1. A micro-electromechanical device (1) for capacitive fluid pressure measurement, the micro-electromechanical device having a first electrode (2) and a second electrode (3) forming a counter electrode, wherein: The device (1) comprises a cavity (6) which is formed between a first bounding layer (5a) and a second bounding layer (5b) or a substrate (4), wherein the first electrode (2) is arranged in the cavity and supported in a movable manner, wherein the first bounding layer (5a) and / or the second bounding layer (5b) can be displaced by fluid pressure (p), and wherein the first bounding layer (5a) and / or the second bounding layer (5b) are coupled to the first electrode (2) via a first coupling element (7a) for transmitting the displacement movement to the movably supported first electrode (2).

2. The device (1) according to claim 1, wherein: The second electrode (3) is arranged in the cavity (6).

3. The device (1) according to claim 1 or 2, wherein: The second electrode (3) is movably supported, and the first delimiting layer (5a) and / or the second delimiting layer (5b) is coupled to the second electrode (3) via a second coupling element (7b) in order to transmit a deflection movement to the second electrode (3).

4. The device (1) according to claim 3, wherein: The first coupling element (7a) and the second coupling element (7b) are arranged on the first electrode (2) and the second electrode (3) in such a way that the first electrode (2) and the second electrode (3) can move in opposite directions to each other.

5. The device (1) according to any one of the preceding claims, wherein: The second electrode (3) and / or the third electrode (20) are arranged in or on the first delimiting layer (5a) and / or in or on the second delimiting layer (5b), or are formed by the first delimiting layer and / or the second delimiting layer.

6. The device (1) according to any one of the preceding claims, wherein: By means of a displacement movement of the first delimiting layer (5a) and / or the second delimiting layer (5b), the first electrode (2) and / or the second electrode (3) can be moved at least in sections in a translational manner.

7. The device (1) according to any one of the preceding claims, wherein: By means of a displacement movement of the first delimiting layer (5a) and / or the second delimiting layer (5b), the first electrode (2) and / or the second electrode (3) can be tilted at least in sections about a tilting axis (8).

8. The device (1) according to claim 7, wherein: The tilting axis (8) is formed by a torsion spring.

9. The device (1) according to claim 7 or 8, wherein: The first electrode (2) and / or the second electrode (3) can be tilted about a plurality of tilting axes (8) spaced apart from one another.

10. The device (1) according to any one of the preceding claims, wherein: The first coupling element (7a) is arranged on a section of the first electrode (2) facing the cavity center (M), and / or the second coupling element (7b) is arranged on a section of the second electrode (3) facing the cavity center (M).

11. The device (1) according to any one of the preceding claims, wherein: The cavity (6) is formed between the first limiting layer (5a) and the second limiting layer (5b), and the second limiting layer (5b) spans a substrate recess (9) introduced into the substrate (4) of the device (1), wherein the first limiting layer (5a) and the second limiting layer (5b) are mechanically connected to each other via a connecting element (10) in such a way that the first limiting layer and the second limiting layer can be deflected together by fluid pressure acting on the first limiting layer (5a) and / or the second limiting layer (5b).

12. The device (1) according to claim 11, wherein The device (1) has a pressure compensation channel (11), which extends through the first limiting layer (5a) and the second limiting layer (5b) and opens into the substrate recess (9).

13. The device (1) according to any one of the preceding claims, wherein: The first electrode (2) and / or the second electrode (3) has a plurality of electrode beams (2b, 3b), which extend substantially parallel to each other.

14. The device (1) according to claim 13, wherein: The electrode beam (2b) of the first electrode (2) is at least partially sunken into the intermediate space of the electrode beam (3b) of the second electrode (3).

15. The device (1) according to any one of the preceding claims, wherein: The device (1) has a plurality of first electrodes (2) and / or one or more second electrodes (3), wherein the plurality of first electrodes and / or the one or more second electrodes are arranged symmetrically with respect to a cavity center (M) in the cavity (6).

16. The device (1) according to any one of the preceding claims, wherein: The device (1) has a rigid frame (12) which divides the cavity (6) into a plurality of sections (22), wherein a first electrode (2) is arranged in each section (22) and can be tilted at least in sections about a tilting axis (8) defined by a torsion spring, wherein the torsion spring is attached to the rigid frame (12).

17. The device (1) according to claim 16, wherein The second electrode (3) and / or the third electrode (20) are arranged in or on the first delimiting layer (5a) and / or in or on the second delimiting layer (5b), or are formed by the first delimiting layer (5a) and / or by the second delimiting layer (5b), and are segmented by one or more segment insulations (21) such that an electrode segment (23) of the second electrode (3) and / or an electrode segment (25) of the third electrode (20) is associated with a segment (22) having a first electrode (2).

18. A microelectromechanical pressure sensor (16), in particular an absolute pressure sensor or a relative pressure sensor, comprising a microelectromechanical device (1) according to any one of the preceding claims and a signal processing unit (17) for applying and processing the signal of the microelectromechanical device (1).

19. A micro-electromechanical microphone for capacitive sound pressure measurement, comprising a micro-electromechanical device (1) according to any one of claims 1 to 17 and a signal processing unit (17), the signal processing unit being used to apply and process the signal of the micro-electromechanical device (1).

20. A micro-electromechanical combined sensor element, comprising a microphone and / or an absolute pressure sensor and / or a relative pressure sensor for capacitive acoustic pressure measurement, wherein: The combined sensor element comprises a micro-electromechanical device (1) according to any one of claims 1 to 17 and a signal processing unit (17) for applying and processing signals of the micro-electromechanical device (1).

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