MEMS device with a counter electrode structure between two membranes

Abstract

MEMS device (100) comprising the following: a first membrane element (102), a second membrane element (104) that is spaced apart from the first membrane element (102), a low-pressure region (106) between the first and the second membrane element (102, 104), wherein the low-pressure region (106) has a pressure that is lower than ambient pressure, and a counter electrode structure (108) comprising a conductive layer (110) that is at least partially located in or extends into the low-pressure region (106), wherein the conductive layer (110) comprises a segmentation (112) that provides electrical insulation between a first section (110a) of the conductive layer (110) and a second section (110b) of the conductive layer (110), wherein the first section (110a) of the conductive layer (110) is a central section of the conductive layer (110) and the second section (110b) of the conductive layer (110) is a boundary section of the conductive layer (110), and wherein the second section (110b) of the conductive layer (110) is electrically connected to the first membrane element (102) and to the second membrane element (104) by means of an electrical connecting element (118, 120).

Description

TECHNICAL FIELD

[0001] Embodiments of the invention relate to a MEMS device (a microelectromechanical system device) having a counter electrode structure between two membranes. BACKGROUND

[0002] When designing transducers (e.g., sound transducers), such as pressure sensors, accelerometers, microphones, or loudspeakers, it may typically be desirable to achieve a high signal-to-noise ratio (SNR) of the transducer's output signal. The ongoing miniaturization of transducers may pose new challenges regarding the desired high signal-to-noise ratio. Microphones and, to some extent, loudspeakers, which can be used in, for example, mobile phones, laptops, and similar (mobile or stationary) devices, can nowadays be implemented as semiconductor (silicon) microphones or microelectromechanical systems (MEMS). To be competitive and deliver the expected performance, silicon microphones may require a high SNR of the microphone output signal.However, taking the condenser microphone as an example, the SNR can typically be limited by the design of the condenser microphone and by the resulting parasitic capacitances.

[0003] Parasitic capacitances are typically unwanted capacitances that interfere with the capacitances between the membrane and the counter electrode. Consequently, the capacitance values ​​intended to be translated into electrical signals in response to the membrane's movement are disturbed. For example, if the MEMS device is embodied as a dual-backplate microphone, the parasitic capacitances can affect the MEMS device, causing the electrical output signal to fail to provide a sufficiently accurate reproduction of the audible sound input signal, i.e., the incoming sound waves.

[0004] DE 10 2015 103 059 A1 refers to a sensor structure for sensing pressure waves and ambient pressure.

[0005] DE 10 2014 212 340 A1 refers to a MEMS microphone with a low-pressure region between the membrane and the counter electrode.

[0006] DE 10 2015 103 236 A1 relates to a MEMS sensor structure for sensing pressure waves and changes in ambient pressure.

[0007] DE 11 2011 105 850 T5 relates to a MEMS microphone with reduced parasitic capacitance. The MEMS microphone comprises a trench that electrically separates an acoustically active portion of the backplate from an acoustically inactive portion of the backplate.

[0008] DE 10 2013 203 379 A1 relates to a tunable MEMS device and a method for manufacturing a tunable MEMS device.

[0009] DE 10 2009 000 583 A1 relates to a component with a micromechanical microphone structure and to a method for operating such a component. SUMMARY

[0010] An embodiment of the invention provides a MEMS device comprising a first membrane element, a second membrane element spaced from the first membrane element, a low-pressure region between the first and second membrane elements, the low-pressure region having a pressure less than ambient pressure, and a counter electrode structure comprising a conductive layer at least partially disposed in or extending into the low-pressure region, the conductive layer comprising segmentation providing electrical isolation between a first portion of the conductive layer and a second portion of the conductive layer.

[0011] Another embodiment provides a MEMS device comprising a first membrane element, a second membrane element spaced from the first membrane element, a low-pressure region between the first and second membrane elements, the low-pressure region having a pressure less than an ambient pressure, and a counter electrode structure comprising a conductive layer at least partially disposed in or extending into the low-pressure region, the first membrane element comprising a segmentation providing electrical isolation between a first portion of the first membrane element and a second portion of the first membrane element, and the second membrane element comprising a further segmentation providing electrical isolation between a first portion of the second membrane element and a second portion of the second membrane element. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Embodiments of the present invention are described herein with reference to the accompanying drawings and figures. Fig. 1a-b show a schematic cross-sectional view and a schematic plan view of a MEMS microphone comprising a segmented counter electrode structure; Fig. 2a-e show schematic partial cross-sections of the segmentation areas of the MEMS microphone of the Fig. 1a-b; Fig. 3a-c show schematic cross-sectional views of a vacuum MEMS microphone (a MEMS loudspeaker or a MEMS sound transducer) comprising a segmented counter electrode structure under different operating conditions; Fig. 4a-b show schematic cross-sectional views of a vacuum MEMS microphone (a MEMS loudspeaker or a MEMS sound transducer) comprising a counter electrode structure with two segmented conductive layers; Fig. 5a-c show schematic partial cross-sectional views of the counter electrode structure of the Fig. 4a-b and the resulting parasitic capacitances between the segmented first and second conductive layers; Fig. 6a-c show schematic floor plans of the segmented counter electrode structure comprising laterally offset segmentation grooves in the first and second conductive layers; Fig. 7a-d show schematic circuit diagrams illustrating readout configurations for the MEMS device; and Fig. 8a-b show schematic cross-sectional views of a vacuum MEMS microphone (a MEMS loudspeaker or a MEMS sound transducer) comprising a first and a second segmented membrane element.

[0013] Before further discussing the present invention in more detail using the drawings, it is noted that in the figures and in the description, identical elements and elements having the same functionality and / or the same technical or physical effect are normally provided with the same reference numerals or are identified with the same name, so that the description of these elements and their functionality as illustrated in the various embodiments are mutually interchangeable or can be applied mutually in the various embodiments. DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0014] In the following description, embodiments of the invention are discussed in detail; however, it should be recognized that the invention provides many applicable inventive concepts that may be embodied in a wide variety of specific MEMS devices. The specific embodiments discussed are merely illustrative of the specific ways of making and using the invention and do not limit the scope of the invention. In the following description of embodiments, the same or similar elements that have the same function are assigned the same reference numerals or names, and a description of such elements is not repeated for each embodiment. Furthermore, the features of the various embodiments described below may be combined with one another unless specifically stated otherwise.

[0015] In the following, embodiments are described with respect to embodiments in the context of MEMS devices in general, wherein the following description may also be applied to any MEMS sound transducer, such as (vacuum) microphones or speakers, pressure sensors, acceleration sensors, actuators, etc.

[0016] In various embodiments of the present invention, the parasitic capacitances for a MEMS device, e.g., a microphone, having a low-pressure region between the membrane (or diaphragm) as the movable structure whose movement is to be capacitively detected with a (e.g., static) backplate electrode (or counter electrode) are reduced or eliminated.

[0017] According to some embodiments, segmentation of the backplate electrode is performed with the purpose of reducing parasitic capacitance to improve microphone performance. More specifically, the signal-to-noise ratio (SNR) of a microphone is increased by a factor k∼11+C0CP, reduced, where C0 is the useful capacity and C p is the parasitic capacitance of the microphone. Consequently, for a given useful capacitance C0, a reduced parasitic capacitance C p to a reduced factor k and consequently to an increased SNR of the converter output signal.

[0018] According to embodiments, the parasitic capacitance for a MEMS microphone, such as a vacuum microphone, can be reduced while maintaining high mechanical robustness. The static electrode of a vacuum microphone is made of a (first) conductive layer divided into an outer portion and an inner portion by a (first) narrow gap, wherein an insulating layer may be formed over the conductive layer. The outer portion of the conductive layer may be electrically connected to the movable structure (i.e., the membrane or diaphragm). If the static electrode comprises a further (second) conductive layer, this conductive layer is further divided into an inner portion and an outer portion by means of a further (second) narrow gap.In this case, the first and second narrow gaps are preferably offset or staggered from each other so that they do not overlap with respect to a vertical projection onto the main surface of the backplate electrode. The outer portions of the two conductive layers can be electrically connected to the movable structure whose movement is to be capacitively detected by the backplate electrode.

[0019] As a variant, the segmentation may alternatively or additionally be applied to the movable structure, i.e., the movable membrane or diaphragm(s). The outer portion of the membrane(s) may be electrically connected to the backplate structure.

[0020] The Fig. 1a-b show a schematic cross-sectional view and a schematic floor plan of a MEMS microphone comprising a segmented counter electrode structure. Fig. Figure 1b shows a plan view of the MEMS device 100 of Fig. 1a with respect to the section plane defined by the dashed line “AA” in Fig. 1a. The dashed line “BB” in Fig. 1b shows the section plane of the cross-sectional view of Fig. 1a.

[0021] The Fig. 1a-b illustrate a concept for a MEMS device 100, e.g., a vacuum MEMS microphone, comprising a first membrane (or diaphragm) element 102 and a second membrane (or diaphragm) element 104 spaced apart from the first membrane element 102. A low-pressure region 106, e.g., a vacuum region or a near-vacuum region, is located between the first membrane element 102 and the second membrane element 104, wherein the low-pressure region 106 has a (gas) pressure less than ambient pressure. A counter electrode structure (or backplate structure) 108 comprises (at least one) conductive layer 110 at least partially disposed within or extending into the low-pressure region 106.The conductive layer includes a segmentation 112 that provides electrical insulation between a first portion 110a of the conductive layer 110 and a second portion 110b of the conductive layer 110.

[0022] To enable the MEMS device 100 to be read differently, the outer section 110b can comprise two electrically isolated sections 110b-1, 110b-2. Consequently, the electrically isolated outer sections 110b-1, 110b-2 of the individual conductive layer are each electrically connected to one of the movable membrane elements 102, 104 to prevent short-circuiting of the two membrane elements 102, 104. By biasing the inner section 110a of the counter electrode 110, the two membrane elements 102, 104 can be read differently, for example.

[0023] As stated above, the counter electrode structure 108 may comprise at least one conductive layer 110, the following description relating to the Fig. 1a-b, Fig. 2a-e and Fig. 3a-c refers to a counter electrode structure comprising, for example, a conductive layer, the following explanations being equally applicable to an arrangement comprising, for example, a counter electrode structure with two electrically separated / insulated layers.

[0024] As in Fig. 1a, (optional) spacer elements 113, 114 may be arranged between the first membrane element 102 and the counter electrode structure 108 and between the second membrane element 104 and the counter electrode structure 108 for holding the first and second membrane elements 102, 104 at a predetermined distance from the counter electrode structure 108.

[0025] As also in Fig. As shown in Figure 1a, the first membrane element 102 comprises a deflectable (movable) portion 102a and a fixed portion 102b, while the second membrane element 104 comprises a deflectable or movable portion 104a and a fixed portion 104b. The fixed portion 102b of the first membrane element 102 is, for example, mechanically connected to the first spacer element 113, while the fixed portion 104b of the second membrane element 104 is mechanically connected (mechanically attached to the second spacer 114) to the second spacer 114. Furthermore, the counter electrode structure 108 is, for example, attached (interleaved) between the first and second spacer elements 113, 114. Consequently, the first portion 110a of the conductive layer 110 is disposed between the deflectable portion 102a of the first membrane element 102 and the deflectable portion 104a of the second membrane element 104.

[0026] Thus, the first portion 110a of the conductive layer 110 is a center or central portion of the conductive layer, and the second portion 110b of the conductive layer 110 is a periphery or edge portion of the conductive layer 110. Thus, the center or central portion 110a can be considered the "electrically active" portion of the conductive layer 110, contributing to the useful capacitance C0 and, consequently, to the useful signal component of the sensor output.

[0027] Consequently, variable active capacitances CA and CB, which in combination form the useful capacitance C0, are formed, respectively. Variable active capacitance CA is formed between deflectable portion 102a of first membrane element 102 and counter electrode structure 108 (i.e., first portion 110a of conductive layer 110), and variable active capacitance CB is formed between deflectable portion 104a of second membrane element 104 and counter electrode structure 108 (i.e., first portion 110a of conductive layer 110).

[0028] As optional in Fig. 1, the second portion 110b of the conductive layer 110 can be electrically coupled to the first membrane element 102 by means of a first connecting element 118 and to the second membrane element 104 by means of a second connecting element 120. The first and second membrane elements 102, 104 can be mechanically coupled. Furthermore, the first and second membrane elements 102, 104 can also be electrically coupled or electrically decoupled (isolated).

[0029] The (optional) mechanical coupling of the first or second membrane element 102, 104 results in a configuration in which a deflection of one of the first and second membrane elements 102, 104 also leads to a corresponding deflection of the other membrane element due to the mechanical coupling. Consequently, the deflection of the first and second membrane elements 102, 104 occurs "in parallel."

[0030] The low-pressure region 106 is located within a sealed cavity formed between the first and second membrane elements 102, 104. More specifically, the sealed cavity may be defined by the first and second membrane elements 102, 104 and the first and second spacer elements 113, 114. The pressure in the low-pressure region 106 is substantially a vacuum or nearly a vacuum.

[0031] As schematically shown above, the first membrane element 102 (and / or the second membrane element 104) may be subjected to an ambient pressure and potentially a sound pressure PSOUND. This side of the membrane element may also be considered a main sound-receiving surface of the MEMS device 100. A deflection of the first membrane element 102 may also result in a corresponding deflection of the second membrane element 104 if they are mechanically coupled. The low-pressure region 106 may have a pressure that may typically be less than an ambient pressure or a standard atmospheric pressure.

[0032] More specifically, according to one embodiment, the pressure in the low-pressure region may be substantially a vacuum or nearly a vacuum. Alternatively, the pressure in the low-pressure region may be less than about 50% (or 40%, 25%, 10%, or 1%) of ambient pressure or standard atmospheric pressure. Standard atmospheric pressure may typically be 101.325 kPa or 1013.25 mbar. The pressure in the low-pressure region may also be expressed as an absolute pressure, e.g., less than 50, 40, 30, or less than 10 kPa.

[0033] Fig. Figure 1b shows an exemplary illustration in the form of a plan view of the MEMS device 100 of Fig. 1a with respect to the section plane defined by the dashed line “AA” in Fig. 1a. The dashed line “BB” in Fig. 1b shows the section plane of the cross-sectional view of Fig. 1a.

[0034] As in Fig. 1b, the first and second membrane elements 102, 104, the counter electrode structure 108, and the segmentation 112 are illustrated as having a quadrangular shape merely by way of example. Alternatively, these elements may also comprise a circular peripheral shape or any other geometrically suitable (polygonal) peripheral shape or configuration.

[0035] As in Fig. 1b, the segmentation 112 (the segmentation element) of the conductive layer 110 is a narrow circumferential gap or recess (e.g., in the form of a segmentation groove) in the conductive layer 110.

[0036] Consequently, the Fig. 1a-b illustrate the MEMS device 100, e.g., a MEMS vacuum microphone, comprising a segmented counter electrode structure 108, i.e., the counter electrode structure comprises the segmented conductive layer 110. The segmentation 112 of the conductive layer 110 may be configured to provide electrical isolation between the first (“active”) portion 110a of the conductive layer 110 and the second (substantially “inactive”) portion 110b of the conductive layer 110.

[0037] The variable active capacitances CA and CB are observed between the deflectable portion 102a of the first diaphragm 102 and the first (active) portion 110a of the conductive layer 10, and between the deflectable portion 104a of the second diaphragm 104 and the first (active) portion 110a of the conductive layer 110. Consequently, the active capacitances CA and CB vary with respect to the movement of the deflectable portions 102a, 104a of the first and second diaphragm elements 102, 104 with respect to the counter electrode structure 108 comprising the conductive layer 110, wherein the movement of the deflection of the first and second diaphragm elements 102, 104 is generated, for example, by sound pressure changes PSOUND caused by speech, music, etc. in the environment.

[0038] In the case of the MEMS device 100 according to the Fig. 1a-b, the first and second membrane elements 102, 104 and the counter electrode structure 108 may have a rectangular shape, wherein, furthermore, the segmentation 112 in the form of the narrow circumferential gap / recess, i.e., the segmentation groove 112, may, for example, also comprise a rectangular circumferential shape. In a further configuration, however, the first and second membrane elements 102, 104 and the counter electrode structure 108 may also have a circular shape, furthermore, the segmentation may be circular. However, it should be understood that regardless of the shape of the first and second membrane elements 102, 104 and / or the counter electrode structure 108, the narrow circumferential gap 112 in the conductive layer 110 may have any suitable (circular, rectangular, (almost closed) polygonal) circumferential shape.The (at least one) conductive layer 110 of the counter electrode structure 108 may be made of an electrically conductive material or may comprise an electrically conductive material, e.g., polysilicon or any metallization. By providing the segmentation of the counter electrode structure 108, the parasitic capacitances can be greatly reduced because the separate and isolated second (inactive) portion 110b of the conductive layer 110, which may be electrically connected to the first or second membrane element, does not contribute (or at least contributes in a very reduced manner) to the generation of parasitic capacitances CP.Consequently, the capacitance of the MEMS device 100 may include both the active capacitance CA generated between the deflectable portion 102a of the first membrane element 102 and the first portion 110a of the conductive layer 110, and the further active capacitance CB between the deflectable portion 104a of the second membrane element 104 and the counter electrode structure 108, i.e., the first portion 110a of the conductive layer 110.

[0039] Based on this approach, the (still remaining) parasitic capacitances CP can be essentially eliminated or at least significantly reduced.

[0040] The Fig. 2a-e now provide, in an exemplary form, several enlarged illustrations of the segmentation 112, which are indicated by the dashed circle 112a in Fig. 1a is specified.

[0041] Fig. 2a shows a configuration in which the conductive layer 110 (at least in the area adjacent to the segmentation 112) is covered by an insulating layer 116, wherein the gap 112 in the conductive layer 110 is at least partially filled with the material of the insulating layer 116, so that electrical insulation is provided between the first portion 110a and the second portion 110b of the conductive layer 110.

[0042] Fig. 2b shows a configuration of the segmentation 112, wherein the gap 112 between the first and second portions 110a, 110b of the conductive layer 110 is completely filled with the material of the insulation layer 116.

[0043] Fig. 2c shows a configuration of the segmentation 112 in which the gap 112 between the first and second portions 110a, 110b of the conductive layer 110 is completely filled with the material of the insulating layer 116 and in which the conductive layer 110 (at least in the region adjacent to the segmentation 112) is completely embedded within the material of the insulating layer 116.

[0044] Fig. 2d shows a configuration in which the insulating layer 116 (at least in the area adjacent to the segmentation 112) covers the conductive layer 110, ie, the first and second portions 110a, 110b, wherein the gap 112 between the first and second portions 110a, 110b of the conductive layer 110 is devoid of any insulating material of the insulating layer 116 (ie, does not comprise any insulating material of the insulating layer 116).

[0045] Fig. 2e shows a configuration in which (only) the gap 112 between the first and second portions 110a, 110b of the conductive layer 110 is filled with an insulating material forming the segmentation 112 that provides the electrical insulation between the first and second portions 110a, 110b of the conductive layer 110.

[0046] As in the Fig. 2a-d, the insulation layer 116 (the insulation carrier or the insulation carrier layer 116) can be arranged (at least in the region adjacent to the segmentation 112) on the conductive layer 110, i.e., the first and second portions 110a, 110b of the conductive layer 110. The insulation layer 116 can be arranged over the entire region of the conductive layer 110 or only over a portion or portions of the conductive layer 110. The insulation layer 116 can be arranged on the surface region of the conductive layer 110 facing the first membrane element 102 or can be arranged on the surface region facing the second membrane element 104. The insulation layer 116 can be silicon dioxide, silicon nitride, a high-k dielectric such as ..., such as silicon dioxide, silicon nitride, a high-k dielectric, such as silicon dioxide, silicon nitride, a high-k dielectric, such as silicon dioxide, silicon nitride, a high-k dielectric, such as silicon B. silicon oxynitride, a polyamide or a combination thereof.

[0047] As shown above, the first portion 110a and the second portion 110b of the conductive layer 110 may be insulated from each other with an insulation gap or an insulation groove that at least partially contains the insulation material of the insulation layer 116. More specifically, the segmentation groove 112 may be filled with a dielectric material, such as silicon dioxide, silicon nitride, or a high-k dielectric, such as silicon oxynitride.

[0048] As in Fig. As shown in Figure 2e, the gap between the first and second portions 110a, 110b of the conductive layer 110 may be filled with an ambient fluid or gas, such as air.

[0049] Fig. 3a-c show schematic cross-sectional views of a vacuum MEMS microphone (a MEMS loudspeaker or a MEMS sound transducer) 100 comprising a segmented counter electrode structure 108 under different operating conditions to explain its functionality.

[0050] As in Fig. As shown in Figure 3a, one or more pillars (or columns or supports) 122 mechanically couple the first membrane element 102 and the second membrane element 104. More specifically, the at least one pillar 122 is mechanically coupled between the deflectable portion 102a of the first membrane element 102 and the deflectable portion 104a of the second membrane element 104.

[0051] If the one or more pillars are electrically conductive, they provide mechanical and electrical coupling between the first and second membrane elements 102, 104. If the one or more pillars are electrically insulating, they provide mechanical coupling and electrical decoupling between the first and second membrane elements 102, 104.

[0052] The pillars (the columns or supports) 122 are typically not in contact or touch with the counter electrode structure 108, but instead may pass through the counter electrode structure 108, i.e., the (at least one) conductive layer 110, via openings or holes 124 in the counter electrode structure 108. In the implementation example shown in Fig. As schematically illustrated in Figure 3a, the pillars 122 may be formed integrally with the first and second membrane elements 102, 104. Consequently, the first membrane element 102, the second membrane element 104, and the pillars 122 may form a one-piece structure of the same material, e.g., polycrystalline silicon (polysilicon). Nevertheless, this does not mean that the first membrane element 102, the second membrane element 104, and the pillars 122 must be formed simultaneously during the fabrication of the MEMS device 100. Instead, it may be possible for the second membrane element 104 to be first formed on a surface of a substrate 126 (or on a surface of an auxiliary layer, such as an etch stop layer) during a (first) deposition process.Subsequently, the pillars 122 and finally also the first diaphragm element 102 can be formed during a subsequent (second) deposition process and possibly during another subsequent (third) deposition process. In alternative implementation examples, the pillars 122 can be made of a different material than the first and second diaphragm elements 102, 104. The first diaphragm element 102 can have a major surface that can face the direction of arrival of a sound. A recess or hole 128 in the substrate 126 forms the backside cavity 128, which is adjacent to the second diaphragm element 104.

[0053] It is noted that although the three central sections of the counter electrode structure 108 as shown in the Fig. 3a-c, appear to be “floating” within the low pressure region 106, they are typically located at the periphery of the counter electrode structure above and / or below the plane of the drawing of the Fig. 3a-c can be attached as indicated by the dashed lines.

[0054] Fig. Figure 3a shows the MEMS device 100 (a MEMS microphone) in its rest position, e.g., when no sound wave arrives at the membrane elements 102, 104 that would cause the membrane elements 102, 104 to be deflected or displaced. Fig. 3b and Fig. 3c show schematic cross-sectional views through the exemplary MEMS device 100, which may be subjected to an incoming sound pressure PSOUND. Fig. Figure 3b shows the situation in which the membrane assembly comprising the first and second membrane elements 102, 104 and the pillars 122 may be pressed downward due to a relative overpressure caused by the sound at the top side adjacent to the first membrane element 102 compared to the reference pressure within the rear cavity 128. In Fig. 3c, the pressure on the sound receiving side may be lower than the pressure within the rear cavity 128, so that the membrane assembly 102, 104, 122 may be deflected upward. Accordingly, the membrane structure moves up and down relative to the counter electrode structure (the stator) 108 under an incoming sound signal PSOUND.

[0055] As an implementation option, the membrane assembly 102, 104, 122 may be a (in the Fig. 3a-c) for static pressure equalization between the ambient atmosphere and the rear cavity 128. The optional vent hole may have a rectangular (or square) cross-section or a circular cross-section, e.g., in the center of the membrane assembly. Consequently, such a vent hole may be configured to promote static pressure equalization between the ambient pressure and the rear cavity 128. Furthermore, as a further option, multiple vent holes may be arranged in the membrane assembly.

[0056] The Fig. 4a-b show schematic cross-sectional views of another MEMS device 200, e.g., a MEMS sound transducer in the form of a vacuum MEMS microphone or a MEMS loudspeaker, comprising a segmented counter electrode structure 108 comprising two segmented conductive layers, i.e., the first segmented conductive layer 110 and the second segmented conductive layer 210.

[0057] As in Fig. As shown in Figure 4a, the counter electrode structure 108 comprises the (first) conductive layer 110 and a further (a second) conductive layer 210, wherein the second conductive layer 210 is electrically insulated from the first conductive layer 110. A further segmentation 212 provides electrical insulation between a first portion 210a of the second conductive layer 210 and a second portion 210b of the second conductive layer 210. Furthermore, an insulating layer 202 may be arranged between the first and second conductive layers 110, 210 of the counter electrode structure 108 to provide insulation and separation of the further portions 110a, 210a of the first and second conductive layers 110, 210.

[0058] The further segmentation 212, the segmentation of the second conductive layer 210, is also a narrow circumferential gap (a second narrow gap) in the second conductive layer 210.

[0059] As further stated in Fig. 4a, (optional) spacer elements 113, 114 may be arranged between the first membrane element 102 and the counter electrode structure 108 and between the second membrane element 104 and the counter electrode structure 108 for holding the first and second membrane elements 102, 104 at a predetermined distance from the counter electrode structure 108.

[0060] As also in Fig. As shown in Figure 4a, the first membrane element 102 comprises a deflectable (movable) portion 102a and a fixed portion 102b, while the second membrane element 104 comprises a deflectable or movable portion 104a and a fixed portion 104b. The fixed portion 102b of the first membrane element 102 is mechanically connected, for example, to the first spacer element 113, while the fixed portion 104b of the second membrane element 104 is mechanically connected (attached to the second spacer 114). Furthermore, the counter electrode structure 108 is attached (interleaved), for example, between the first and second spacer elements 113, 114. Consequently, the first portion 110a of the first conductive layer 110 is disposed between the deflectable portion 102a of the first membrane element 102 and the deflectable portion 104a of the second membrane element 104.

[0061] Thus, the first portion 110a of the first conductive layer 110 is a central or center portion of the conductive layer, and the second portion 110b of the first conductive layer 110 is an edge portion of the conductive layer 110. Thus, the central portion 110a can be considered the "electrically active" portion of the first conductive layer 110, contributing to the useful capacitance C0 and, consequently, to the useful signal component of the sensor output signal. Furthermore, the first portion 210a of the second conductive layer 110 is a central or center portion of the second conductive layer 210, and the second portion 210b of the second conductive layer 210 is an edge portion of the second conductive layer 210.Consequently, the center portion 210a can be considered the “electrically active” portion of the conductive layer 210, contributing to the useful capacitance C0 and hence to the useful signal component of the sensor output.

[0062] Consequently, variable active capacitances CA and CB, which in combination form the useful capacitance C0, are formed, respectively. Variable active capacitance CA is formed between deflectable portion 102a of first membrane element 102 and counter electrode structure 108 (i.e., first portion 110a of first conductive layer 110), and variable active capacitance CB is formed between deflectable portion 104a of second membrane element 104 and the counter electrode structure (i.e., first portion 210a of second conductive layer 210).

[0063] As optional in Fig. As shown in Figure 4a, the second portion 110b of the first conductive layer 110 may be electrically coupled to the first membrane element 102 by means of a first connecting element 118, and the second portion 210b of the second conductive layer 210 may be electrically coupled to the second membrane element 104 by means of a second connecting element 120. The first and second membrane elements 102, 104 may be mechanically coupled. Furthermore, the first and second membrane elements 102, 104 may also be electrically coupled or electrically decoupled (isolated).

[0064] Furthermore, an optional electrical connection 230 may be provided for electrically connecting the second portions 110b and 210b of the first and second conductive layers 110, 210.

[0065] The (optional) mechanical coupling of the first and second membrane elements 102, 104 results in a configuration in which a deflection of one of the first and second membrane elements 102, 104 also leads to a corresponding deflection of the other membrane element due to the mechanical coupling. Consequently, the deflection of the first and second membrane elements 102, 104 occurs (essentially) "in parallel."

[0066] The low-pressure region 106 is located within a sealed cavity formed between the first and second membrane elements 102, 104. More specifically, the sealed cavity may be defined by the first and second membrane elements 102, 104 and the first and second spacer elements 113, 114. The pressure in the low-pressure region 106 is substantially a vacuum or close to a vacuum.

[0067] As schematically shown above, the first membrane element 102 (and / or the second membrane element 104) may be subjected to an ambient pressure and potentially a sound pressure PSOUND. This side of the membrane element may also be considered a main sound-receiving surface of the MEMS device 100. A deflection of the first membrane element 102 may also result in a corresponding deflection of the second membrane element 104 if they are mechanically coupled. The low-pressure region 106 may have a pressure that may typically be less than an ambient pressure or a standard atmospheric pressure.

[0068] As in Fig. 4a, the segmentations 112, 212 (the segmentation element) of the first and second conductive layers 110, 210 are narrow circumferential gaps or recesses (e.g., in the form of a segmentation groove) in the respective first and second conductive layers 110, 210.

[0069] The variable active capacitances CA and CB are observed between the deflectable portion 102a of the first membrane 102 and the first (active) portion 110a of the first conductive layer 10 and between the deflectable portion 104a of the second membrane 104 and the first (active) portion 210a of the second conductive layer 210. Consequently, the active capacitances CA and CB can vary in the form of capacitance variations ΔCA and ΔCB based on the movement Δx1, Δx2 of the deflectable portion 102a, 104a of the first and second membrane elements 102, 104, respectively, with respect to the counter electrode structure 108 comprising the conductive layers 110, 210, wherein the movement or deflection Δx1, Δx2 of the first and second membrane elements 102, 104, e.g. B. can be generated by sound pressure changes PSOUND caused by speech, music, etc.

[0070] In the case of the MEMS device 100 of the Fig. 4a-b, the first and second membrane elements 102, 104 and the counter electrode structure 108 may have a rectangular shape, wherein, furthermore, the segmentations 112, 212 in the form of the narrow circumferential gap / recess, i.e., the segmentation grooves 112, 212, may also comprise a rectangular shape. However, it should be understood that the first and second membrane elements 102, 104 and the counter electrode structure 108 may have a circular shape, furthermore, the segmentation may be circular. However, it should be understood that, regardless of the shape of the first and second membrane elements and / or the counter electrode structure 108, the narrow circumferential gap in the first conductive layer 110 and the second conductive layer 210 may have any suitable (circular, rectangular, (almost closed) polygonal) circumferential shape.The (at least one) conductive layer 110 of the counter electrode structure 108 may be made of an electrically conductive material or may comprise an electrically conductive material, e.g., polysilicon or any metallization. By providing the segmentation of the counter electrode structure 108, the parasitic capacitances can be greatly reduced because the separate and isolated second (inactive) portion 110b of the first conductive layer 110 and the second (inactive) portion 210b of the second conductive layer 210, which may be electrically connected to the first and second membrane elements, respectively, do not contribute (or at least in a very reduced manner) to the generation of parasitic capacitances. Consequently, the capacitance of the MEMS device 100 as a whole may include both the active capacitance CA, which exists between the deflectable portion 102a of the first membrane element 102 and the counter electrode structure 108, i.e.,, the first portion 110a of the first conductive layer 110, as well as the further active capacitance CB between the deflectable portion 104a of the second membrane element 104 and the counter electrode structure 108, ie the first portion 210a of the second conductive layer 210.

[0071] Based on this approach, the (still remaining) parasitic capacitances CP can be essentially eliminated or at least significantly reduced.

[0072] As stated above, the counter electrode structure 108 of the MEMS device 200 may comprise two conductive layers 110, 210, wherein the above description regarding the Fig. 2a-e, which relates to a counter electrode structure comprising, for example, a conductive layer, is also equally applicable to the second conductive layer 210 (and the further insulation layer 216) of the MEMS device 200.

[0073] Consequently, the further insulation layer 216 can be arranged, for example, on the surface region of the second conductive layer 210 facing the second membrane element 104. The insulation layer 216 can comprise silicon dioxide, silicon nitride, a high-k dielectric such as silicon oxynitride, a polyamide, or a combination thereof.

[0074] As in Fig. 4a, the second narrow gap 212 in the second conductive layer 210 is filled with an insulating material. However, further optional implementations regarding the first narrow gap 112 and the second narrow gap 212 will be described with respect to Fig. 5a and Fig. 5b is illustrated below as an example.

[0075] The first portion 210a of the second conductive layer 210 is a center or central portion of the second conductive layer 210, and the second portion 210b of the second conductive layer 210 is an edge or periphery portion of the second conductive layer. The first membrane element 102 includes the deflectable portion 102a and the fixed portion 102b, and the second membrane element 104 includes the deflectable portion 104a and the fixed portion 104b. Thus, the first portion 110a of the first conductive layer 110 faces the deflectable portion 102a of the first membrane element 102, and the first portion 210a of the second conductive layer 210 faces the deflectable portion 104a of the second membrane element 104.Furthermore, a first spacer 113 (a first spacer element) is disposed between the first membrane element 102 and the first conductive layer 110, and a second spacer 114 (a second spacer element) is disposed between the second membrane element 104 and the second conductive layer 210 at their respective edge portions. As shown in FIG. Fig. As shown in Figure 4a, the narrow circumferential gap 112 in the first conductive layer 110 is located (with respect to a vertical projection) outside the first spacer element 113, while the circumferential gap 112 in the second conductive layer 210 is located, with respect to a vertical projection, inside the second spacer element 114. However, this configuration of the first and second narrow gaps 112 and 212 is merely an exemplary implementation, wherein, based on the necessary structural robustness of the counter electrode structure 108, the relative positions of the first and second narrow gaps 112, 212 with respect to each other and with respect to the first and second spacer elements 113, 114 may be appropriately adjusted, as will be described in detail below.

[0076] In the following, the distance d1 describes the distance between (the adjacent edges) of the first narrow gap 112 and the first spacer element 113 (with respect to a vertical projection) and the distance d2 describes the distance between (the adjacent edges) of the second narrow gap 212 and the second spacer element 114 (with respect to a vertical projection), wherein the distance d3 describes the distance between (the adjacent edges) of the first and second narrow gaps 112 and 212 (with respect to a vertical projection and assuming a substantially constant distance between the first and second narrow gaps). The distances are also in Fig. 5c shown below.

[0077] The following evaluations further show that the specifically selected values ​​for the distances d1, d2, and d3 are made with respect to a compromise between the necessary robustness of the resulting counter electrode structure 108 and the resulting parasitic capacitances originating from the counter electrode structure 108. The larger and equal the selected distances d1 and d2 are, the smaller the resulting parasitic capacitances originating from the first and second conductive layers 110, 210 are. However, if the distances d1 and d2 are increased in the same relationship, the resulting useful capacitances CA, CB decrease due to the correspondingly reduced (active) area of ​​the deflectable portion 102a of the first membrane element 102 and the deflectable portion 104a of the second membrane element 104.Moreover, the larger the distance d3 between the first and second narrow gaps 112, 212, the greater the resulting mechanical robustness of the counter electrode structure 108, while having asymmetric electrical properties of the first and second conductive layers 110, 210.

[0078] Since the narrow circumferential gap 112 in the first conductive layer 110 is laterally offset from the narrow circumferential gap 212 of the second conductive layer 210 with respect to a vertical projection, the first and second narrow gaps 112, 212 in the first and second conductive layers 110, 210 are arranged in a non-overlapping configuration.

[0079] Fig. Figure 4b shows a schematic cross-sectional view of a vacuum MEMS microphone 200 comprising a segmented counter electrode structure 108 having two segmented conductive layers 110, 210. More specifically, the illustration of the vacuum MEMS microphone differs from Fig. 4b from the illustration in the Fig. 3a-c insofar as the segmented counter electrode structure 108, in contrast to the one segmented conductive layer 110 of the Fig. 3a-c comprises two segmented conductive layers 110, 210. Consequently, the explanations in the context of Fig. 3a-c equally apply, for example, to the arrangements of the Fig. 4a-b, which has a counter electrode structure 108 with two electrically separated / insulated conductive layers 110, 210.

[0080] The Fig. 5a-b show schematic partial cross-sectional views of exemplary segmentation regions of the counter electrode structure 108 according to the Fig. 4a-b.

[0081] As in Fig. 5a, the segmentation is a gap 112, 212 through the first and second conductive layers 110, 210 and the insulating layer 202. Consequently, the distance d3 between (the adjacent edges of) the first and second narrow gaps 112 and 212 is zero. As shown in Fig. As shown in Figure 5a, the gap 112 is substantially unfilled, since only the thin (optional) insulating layer 116 covers the first main surface of the first conductive layer 110 and the surface of the gap 112. Moreover, a further (optional) insulating layer 216, which may comprise a nitride material, may be arranged on the main surface area of ​​the second conductive layer 210. The thickness of the first and second optional insulating layers 116, 216 may be selected to achieve sufficient mechanical strength or robustness of the resulting counter electrode structure 108.

[0082] Fig. 5b shows a configuration in which the first and second narrow circumferential gaps 112, 212 are laterally offset from each other (by the distance d3). The first main surface area of ​​the first conductive layer 110 and the narrow circumferential gap 112 may be covered with the optional insulating layer 116. Furthermore, the second narrow circumferential gap 212 may extend up to the second conductive layer 210 and at least partially into / through the insulating layer 202. In this configuration according to Fig. 5b, the insulating layer 202 is partially interrupted. This structure of the second circumferential gap 212 with the partially interrupted insulating layer 202 can be achieved by etching the insulating layer 202 during the release etch of the cavity 106 in the substrate beneath the MEMS device, i.e., the vacuum MEMS microphone.

[0083] For example, the etching of the insulating layer 202 may be performed while the material present within the cavity 106 defined by the two membranes is being etched. The backside cavity 128 may be etched later (than the etching of the insulating layer 202), with the etching of the backside cavity 128 not disturbing the insulating layer 202.

[0084] The at least partial removal of the material of the insulating layer 202 forming the second narrow circumferential gap 212 provides a lower parasitic capacitance at the level of the second narrow gap 212 compared to the case where it is filled with an oxide material.

[0085] Fig. Figure 5c schematically shows the resulting and remaining (most dominant) parasitic capacitances CP1-3 caused by the segmented first and second conductive layers 110, 210. Due to the segmentation of the first and second conductive layers 110, 210 and the electrical connection of the second portion 110b of the first conductive layer 110 to the first membrane element 102 and the second portion 210b of the second conductive layer to the second membrane element 104, the resulting parasitic capacitances can be greatly reduced because the isolated (separated) portions 110b, 210b of the first and second conductive layers 110, 210 contribute only slightly to the generation of parasitic capacitances.The resulting reduced capacitances are CP1 between the first and second portions 110a, 110b of the first conductive layer, CP2 between the first and second portions 210a, 210b of the second conductive layer 210, and CP3 between the second conductive portion 110b of the first conductive layer 110 and the first portion 210a of the second conductive layer.

[0086] The distance d1 describes the distance between (the adjacent edges) of the first narrow gap 112 and the first spacer element 113 (with respect to a vertical projection) and the distance d2 describes the distance between (the adjacent edges) of the second narrow gap 212 and the second spacer element 114 (with respect to a vertical projection), wherein the distance d3 describes the distance between (the adjacent edges) of the first and second narrow gaps 112 and 212 (with respect to a vertical projection and assuming a substantially constant distance between the first and second gaps).

[0087] The parasitic capacitance CP3 is based on the displacement (the distance d3) between the first and the second narrow gap 112, 212. Since an increased distance d3 provides increased mechanical robustness of the resulting counter electrode structure 108, the distance d3 should be chosen as small as possible to limit the parasitic capacitance CP3 between the second portion 110b of the first conductive layer and the first portion 210a of the second conductive layer, as shown in Fig. 5c is specified.

[0088] The following describes an exemplary relationship between the distances d1, d2, and d3 and the resulting parasitic capacitances CP1, CP2, and CP3. The parasitic capacitance Cp1, for example, is essentially proportional to the width and length of the narrow gap 112, the thickness of the layer 110, and the dielectric constant of the material in the plane of the gap 112. The same applies to the parasitic capacitance Cp2. The parasitic capacitances Cp1 and Cp2 can typically be > 0.1 pF. The parasitic capacitance Cp3, for example, is proportional to the distance d3, the length of the segmentation line (therefore, it depends on the size of the central portion 110a), and the dielectric constant of the material of the insulating layer 202. For a 1 mm 2-Counter electrode structure 108 and a distance d3 of 4 µm, the parasitic capacitance Cp3 is in the order of 1 pF (compared to a parasitic capacitance 5 to 10 times higher without segmentation).

[0089] Since the resulting signal-to-noise ratio of the output signal of the MEMS device 100 depends on the following relationship 1 / (1 + c0 / cp), it is clear that an increased useful capacitance C0 and a reduced total parasitic capacitance CP based on a combination of CP1, CP2 and CP3 leads to an increased signal-to-noise ratio SNR.

[0090] Below are some exemplary and typical dimensions and materials of the various elements that are relevant to the Fig. 1a-b, Fig. 2a-e, Fig. 3a-c, Fig. 4a-b and Fig. 5a-c are described below.

[0091] The first membrane element 102 may be formed as a conductive layer comprising polysilicon, wherein the layer may have a thickness in the range of 0.5 µm, typically from 0.1 to 2 µm, from 0.2 to 1 µm, or from 0.3 to 0.7 µm. The second membrane element 104 may be formed as a conductive layer comprising polysilicon, wherein the layer may have a thickness in the range of 0.5 µm, typically from 0.1 to 2 µm, from 0.2 to 1 µm, or from 0.3 to 0.7 µm.

[0092] The first conductive layer 110 may be formed as a conductive layer comprising polysilicon, wherein the layer may have a thickness in the range of 0.5 µm, typically from 0.1 to 2 µm, from 0.2 to 1 µm, or from 0.3 to 0.7 µm. The second conductive layer 210 may be formed as a conductive layer comprising polysilicon, wherein the layer may have a thickness in the range of 0.5 µm, typically from 0.1 to 2 µm, from 0.2 to 1 µm, or from 0.3 to 0.7 µm.

[0093] The thickness of the first and second spacer elements 113, 114 and consequently the distance between the first membrane element 102 and the counter electrode structure 108 and between the second membrane element 104 and the counter electrode structure 108 (i.e., the gaps between the movable sections and the static electrodes) is in the range of 2 µm, typically between 0.5 and 5 µm, between 1 and 3 µm, or between 1.5 and 2.5 µm.

[0094] The thickness of the insulating layer 202, which may comprise an oxide material, between the first and second conductive layers 110 and 210 (i.e., between the two static electrodes 110, 210) is in the range of 0.3 µm and typically between 0.1 and 1 µm, between 0.2 and 5 µm, or between 0.25 and 0.35 µm. The oxide material may be, for example, silicon dioxide SiO2.

[0095] The thickness of the first and second optional layers 116, 216, which at least partially cover the first conductive layer 110 and the second conductive layer 210, respectively (i.e., on and below the static electrode stack), is in the range of 0.1 µm and typically between 0.03 and 0.3 µm, between 0.05 and 0.2 µm, or between 0.07 and 0.13 µm. The optional insulating layers 116, 216 may comprise silicon nitride (SiN).

[0096] The first and second membrane elements 102, 104 and the counter electrode structure, i.e., the movable and static membranes / layers, may have geometric (perimeter) shapes such as a circle, an oval, a square, a rectangle, and may have lateral dimensions (an average external diameter) in the range of 1 mm and typically between 0.1 and 5 mm, between 0.5 and 2 mm, or between 0.8 and 1.5 mm.

[0097] The narrow gaps 112, 212 are (preferably) located outside the anchored region (i.e. the anchoring region of the first and second spacer elements 113, 114), wherein the distance (d1 or d2) between (the adjacent edges of) the outer narrow gap and the associated anchoring region (i.e. the first spacer element with respect to the first conductive layer 110 and the second spacer element 114 with respect to the second conductive layer 210) can be in the typical range of 10 µm, typically between 1 and 20 µm, between 5 and 15 µm or between 8 and 12 µm, but can also vary, for example, from 1 µm to half the radius of the respective membrane element 102, 104.

[0098] At least one or both narrow gaps 112, 212 may also be located within the anchoring region, ie, below (under) the first or second spacer element 113, 114 with respect to a lateral projection. Such an arrangement of the first and / or second narrow gaps 112, 212 may, however, provide increased mechanical robustness of the resulting counter electrode structure, but may lead to increased parasitic capacitances.

[0099] Below, some typical dimensions of the narrow gaps 112, 212 are discussed with regard to the resulting influence on the remaining parasitic capacitances. The lateral dimensions of the narrow gaps 112, 212 are typically in the range between 0.1 and 10 µm, between 1.0 and 8 µm, or between 3 and 5 µm. The lateral dimension of the narrow gaps describes the distance between the first and second sections 110a-110b, 210a-210b of the first and second conductive layers 110, 210. The lateral dimensions of the first and second narrow gaps are chosen to be sufficiently large to minimize the remaining parasitic capacitances CP1 or CP2. The first and second narrow gaps 112, 212 in the first and second conductive layers 110, 210 may be laterally offset from each other with respect to a vertical projection onto the counter electrode structure 108, ie, they may be arranged in a non-overlapping configuration.

[0100] Such a non-overlapping configuration of the two narrow gaps 112, 212 makes it possible to avoid any mechanical weak point of the resulting counter electrode structure 108. However, the lateral displacement (the distance d3) should be as minimal as possible to reduce the remaining parasitic capacitance CP3. Consequently, a typical dimension for the distance d3 is in the range of a few micrometers. The two narrow gaps 112, 212 can be located, with respect to a vertical projection, within the anchoring region formed by the first and second spacer elements 113, 114. However, to reduce the resulting parasitic capacitances CP1, CP2, at least one of the two narrow gaps 112, 212 should be located outside the anchoring region 115, 117 (see, for example, the Fig. 6a-b).

[0101] In order to provide a balance between the remaining parasitic capacitance CP3 between the first and second conductive layers 110, 210, the distance d3 between the first and second narrow gaps 112, 212 may, for example, be “inverted”, as described below in Fig. 6b is specified.

[0102] To avoid any crossing of the first and second narrow gaps 112, 212 (with respect to a vertical projection), the inversion of the displacement (the distance d3) can be performed at the level of a hole in the respective electrode (of the first or second conductive layer 110, 210) or at the boundary of the electrode (of the first or second conductive layer 110, 210), e.g., where the respective electrode is anchored. In the case of holes in the electrodes (of the first and / or second conductive layer 110, 210, e.g., for release purposes), the respective narrow gap 112, 212 (the respective segmentation) should avoid these holes with a pitch of typically or at least 0.5 µm. The shape of the segmentation line can be adapted to avoid the holes, e.g., by means of a sinusoidal shape of the segmentation line (the narrow gap).

[0103] The Fig. 6a-c show schematic floor plans of the segmented counter electrode structure 108 or a portion thereof, which includes the laterally offset segmentation grooves / gaps 112, 212 in the first and second conductive layers 110, 210.

[0104] As in the Fig. 6a and Fig. As shown in Figure 6b, the (almost closed) narrow circumferential gap 112 in the first conductive layer 110 is laterally offset from the narrow circumferential gap 212 in the second conductive layer 210 with respect to a vertical projection onto the narrow circumferential gap 212 in the second conductive layer 210. Consequently, the first and second narrow circumferential gaps 112, 212 in the first and second conductive layers are arranged in a non-overlapping configuration (with respect to a vertical projection of the narrow circumferential gap 112 in the first conductive layer 110 onto the narrow circumferential gap 212 in the second conductive layer 210). Consequently, a non-overlapping configuration of the first and second narrow circumferential gaps 112, 212 in the first and second conductive layers 110, 210 is achieved.

[0105] Regarding the Fig. 6a-c it should be stated that the indicated narrow circumferential gaps 112, 212 are located in different (vertically offset) planes with respect to the drawing planes of the Fig. 6a-c. The anchored region defines the region of the spacer elements 113, 114 between the first membrane element 102 and the counter electrode structure 108 and between the second membrane element 104 and the counter electrode structure 108.

[0106] As in Fig. 6a, the connecting elements 118, 120 (ie the wiring to the respective first and second membrane elements 102, 104) are located in the same side region of the counter electrode structure 108.

[0107] As in Fig. 6b, the counter electrode structure 108 comprises two contact areas at two diagonally opposite positions of the counter electrode structure 108. Based on this configuration of Fig. 6b, the first narrow circumferential gap 112 may be divided into first and second partial gaps 112a, 112b, and the second narrow circumferential gap 212 may be divided into first and second partial gaps 212a, 212b. Since the first narrow gaps 112a, 212a are arranged in a "mirrored configuration" with respect to the respective distance from the anchoring region 115, 117 or with respect to the boundary of the counter electrode structure 108, and due to the mirrored configuration of the second partial gaps 112b, 212b with respect to each other, the remaining parasitic capacitances between the first and second conductive layers may be (substantially) balanced. More specifically, a “displacement inversion” of the first and second narrow circumferential gaps 112 (= 112a + 112b), 212 (= 212a + 212b) is formed with respect to the boundary of the counter electrode structure in order to compensate for the remaining parasitic capacitances.

[0108] As in Fig. 6c with respect to an enlarged partial view of the counter electrode structure 108, openings or holes 108a may be provided in at least one of the first and second conductive layers 110, 210. The holes 108a in the first and / or second conductive layers 110, 210 may be provided, for example, for stress relief reasons. To avoid an undesirable decrease in the mechanical robustness of the resulting counter electrode structure 108, the first and second narrow circumferential gaps 112, 212 may have a shape, e.g., a sinusoidal shape, to avoid connecting or intersecting the hole(s) 108a in the first and / or second conductive layers 110, 210 of the counter electrode structure 108. As shown in Fig. 6c, the first and second (vertically offset) narrow circumferential gaps 112, 212 are arranged as sinusoidal segmentation lines. It should be noted that any other suitable shape, e.g., zigzag, etc., of the respective segmentation lines may be selected and adapted to prevent the first and / or second narrow circumferential gaps 112, 212 from contacting or intersecting at least one of the plurality of holes in the counter electrode structure 108. Consequently, the distance d3 between the first and second narrow gaps 112, 212 should be greater than the diameter of the holes 108a and less than the length L (which is the diameter of the holes 108a plus the distance between the holes 108a).

[0109] The above explanations regarding the shape of the segmentation line in the first and / or the second conductive layer 110, 210 are correspondingly applicable to the case where a segmentation is provided in the first and / or the second membrane element 102, 104, as described below with respect to the Fig. 8a-b.

[0110] The Fig. 7a-d show various schematic circuit diagrams illustrating various exemplary readout configurations for the MEMS device 100 (the vacuum MEMS microphone described above) described above.

[0111] Fig. 7a shows a schematic circuit diagram illustrating another exemplary readout configuration for the MEMS device 100 having a counter electrode structure 108 with an active conductive layer 110.

[0112] As in Fig. As shown in Figure 7a, the first portion 110a of the first conductive layer 110 is connected to a potential V1, so that the first portion 110a is polarized with the voltage V1. The movable structure 102, 104, i.e., the first and second membrane elements 102, 104, are read out by a differential amplifier 306, wherein the first and second membrane elements 102, 104 are each connected to a different input connection of the differential amplifier 306, which provides the output signal SOUT. Consequently, Fig. 7a provides a differential readout configuration for a vacuum MEMS microphone having a conductive layer.

[0113] Regarding the configuration according to Fig. 7a should state that the (in Fig. 7a) that are mechanically coupled between the first and second membrane elements 102 and 104 to provide a mechanical coupling between the first and second membrane elements 102, 104, should not provide an electrical connection between the first and second membrane elements 102, 104 to enable the differential readout configuration of the first and second membrane elements 102, 104. Consequently, the pillars 122 that ensure a mechanical coupling between the first and second membrane elements 102, 104 do not provide an electrical connection between the two membrane elements, wherein the pillars 122 are made of an insulating material such as silicon, nitride, silicon oxide, a polymer, or a combination of the previous materials, or a combination of the previous materials with a conductive layer (e.g.,silicon), provided that the conductive portion of the pillars is separated from the membrane elements 102, 104 by an insulating material.

[0114] Regarding a differential readout configuration of a vacuum MEMS microphone 100 with a single conductive layer 110 as the counter electrode structure 108, it should be noted that the (single) conductive layer 110, i.e., the counter electrode, is divided into an outer portion 110b and an inner portion 110a, wherein the outer portion 110b comprises two electrically isolated portions 110b-1, 110b-2. Consequently, the electrically isolated outer portions 110b-1, 110b-2 of the single conductive layer are each electrically connected to one of the movable membrane elements 102, 104 to prevent short-circuiting of the two membrane elements 102, 104. By biasing the inner portion 110a of the counter electrode 110, the two membrane elements 102, 104 can be read differently.

[0115] As an alternative and possible implementation, the movable membrane element 102 may be electrically connected to the outer portion 110b of the single conductive layer 110 (e.g., in one portion), wherein the further membrane element 104 is not electrically connected to the outer portion 110b of the single conductive layer 110. As a further possible implementation, the movable membrane element 104 may be electrically connected to the outer portion 110b of the single conductive layer 110 (e.g., in one portion), wherein the further membrane element 102 is not connected to the outer portion 110b of the single conductive layer 110.

[0116] Fig. Figure 7b schematically illustrates an example of how the MEMS microphone can be electrically connected to a power supply circuit and a readout amplifier. Fig. Figure 7b shows an example of a possible connection, although other arrangements and configurations may also be possible.

[0117] In Fig. 7b, the first and second membrane elements 102, 104 may be connected (e.g., grounded) to an electrical reference potential VREF (e.g., a ground potential) by a membrane connection 302. The first portion 110a of the first conductive layer may be electrically connected to a first connection 304 to a first power supply circuit 307 and also to a first input of an amplifier 306. The first power supply circuit 307 includes a voltage source 308 (providing a first potential V1) and a resistor 310 having a very high resistance (several gigaohms or higher). The amplifier 306 may be a differential amplifier. The first portion 210a of the second conductive layer 210 may be connected to a second connection 312 to a second power supply circuit 313 and a second input of the amplifier 306.The second power supply circuit 313 includes a second voltage source 314 (providing a second potential V2) and a second resistor 316, which typically has approximately the same resistance as the first resistor 310. The first and second power supply circuits 307, 313 electrically bias the first portions 110a, 210a of the first and second conductive layers 110, 210, respectively, against the electrical reference potential VREF (e.g., ground potential).

[0118] If the membrane structure can be deflected in response to the incoming sound pressure, the electrical potentials at the first sections 110a, 210a of the first and second conductive layers 110, 210 can change in opposite directions due to the changing capacitances CA, CB between the first membrane element 102 and the first section 110a of the first conductive layer 110 and between the second membrane element 104 and the first section 210a of the second conductive layer 210, respectively. Fig. 7b by a first signal form 317 and a second signal form 318, which can be fed into the first and second inputs of amplifier 306, respectively. Amplifier 306 can generate an amplified output signal 320 based on the input signals at first and second connections 304 and 312, in particular based on a difference between the input signals. The amplified output signal 320 can then be fed to further components for subsequent signal processing, e.g., analog-to-digital conversion, filtering, etc.

[0119] Fig. 7c shows another schematic circuit diagram for another exemplary readout configuration for the MEMS device 100. As in Fig. 7c, the first and second membrane elements 102, 104 are connected to a voltage source 350 to apply a reference potential V for the first and second membrane elements 102, 104. This provides a polarization with the potential V of the movable structure, i.e., the first and second membrane elements 102, 104. Furthermore, the first portions 110a, 210a of the first and second conductive layers 110, 210 are each connected to different input connections of a differential amplifier 306 for providing a differential readout configuration of the MEMS device 100 (the vacuum MEMS microphone). Consequently, according to the configuration of Fig. 7c, a deflection of the membrane structure 102, 104 in response to an incoming sound pressure / signal and a corresponding output signal SOUT is provided by the amplifier 306, which indicates the current deflection of the movable structure 102, 104.

[0120] Consequently, the movable portions 102, 104 (ie, the first and second membrane elements 102, 104) are polarized with a voltage V1, whereby a different sensing / reading is performed on the static electrode 108, ie, the first portions 110a, 210a of the first and second conductive layers 110, 210.

[0121] Fig. Figure 7d shows a schematic circuit diagram of another illustrative readout configuration for the MEMS device 100. More specifically, as in Fig. 7d, the first portion 110a of the first conductive layer is connected to a first potential V1, ie polarized with a first voltage V1, wherein the first portion 210a of the second conductive layer 210 is connected to a second potential V2, so that the first portion 210a of the second conductive layer is polarized with the second voltage V2.

[0122] The movable structure 102, 104, i.e., the first and second membrane elements 102, 104, are connected to a common input connection of a (single-ended) amplifier 309 for providing the amplified output signal SOUT based on an asymmetric readout. Due to the polarization of the first sections 110a, 210a of the first and second conductive layers 110, 210, a deflection of the membrane structure 102, 104 results in electrical potentials at the first and second membrane elements 102, 104, which can be fed in a superimposed manner to an input of the amplifier 309.

[0123] In summary, the two electrodes (the first sections 110a, 210a of the first and second conductive layers 110, 210) of the static membrane (the counter electrode structure 108) are polarized with different voltages V1, V2, e.g., opposite voltages with V2 = -V1. Consequently, the movable structure can be read based on a single-ended amplifier configuration (an asymmetric readout).

[0124] The Fig. 8a-b show schematic cross-sectional views of further exemplary MEMS devices, e.g., a MEMS sound transducer (a vacuum MEMS microphone or a MEMS vacuum loudspeaker), comprising a first segmented membrane element 402 and a second segmented membrane element 404.

[0125] The MEMS device (vacuum MEMS microphone) 400 includes a first membrane element 402 and a second membrane element 404 spaced apart from the first membrane element 402. A low-pressure region 406 is located between the first and second membrane elements 402, 404, wherein the low-pressure region 406 has a pressure less than ambient pressure. A counter electrode structure 408 includes a conductive layer 410 at least partially disposed within or extending into the low-pressure region 406. The first membrane element 402 includes a segmentation 412 that provides electrical insulation between a first portion 402a of the first membrane element 402 and a second portion 402b of the first membrane element 402.The second membrane element 404 includes a further segmentation 424 that provides electrical insulation between a first portion 404a of the second membrane element 404 and a second portion 404b of the second membrane element 404.

[0126] The segmentation 412 of the first membrane element 402 is a narrow circumferential gap in the first membrane element 402, wherein the segmentation 424 of the second membrane element 404 is another (second) narrow circumferential gap in the second membrane element 404. The first portion 402a of the first membrane element 402 is a center or central portion of the first membrane element 402, wherein the second portion 402b of the first membrane element 402 is an edge portion of the first membrane element 402. The first portion 404a of the second membrane element 404 is a center or central portion of the second membrane element 404, wherein the second portion 404b of the second membrane element 404 is an edge portion of the second membrane element 404. As in Fig. 8a, the first membrane element 402 may be at least partially covered with or embedded in an insulating material 416, wherein the second membrane element 404 may also be covered with or embedded in a further insulating material 420.

[0127] The first portion 402b of the first membrane element 402 and the first portion 404b of the second membrane element 404 are electrically connected to the conductive layer 410 by a first and a second connection 422, 423.

[0128] Consequently, the connecting elements 422, 423 provide electrical connections between the static electrode(s) 410 and the outer portions 402b, 404b of the segmented membrane 402, 404. As shown in Fig. 8a, the counter electrode structure 408 (the back plate) may be a simple uniform conductive layer 410.

[0129] The MEMS device 400 may further comprise one or more (in the Fig. 8a-b not shown) for mechanically coupling the first membrane element and the second membrane element 402, 404. In the case of a counter electrode structure 408 having a single conductive layer 410, the (in Fig. 8a) ensure a mechanical coupling, but not an electrical connection, between the two membrane elements 402, 404. Consequently, the pillars can be made at least partially of an insulating material.

[0130] Furthermore, a first spacer element 413 is arranged between the first membrane element 402 and the counter electrode structure 408, and a second spacer element 414 is arranged between the second membrane element 404 and the counter electrode structure 408. Furthermore, the narrow circumferential gap 412 in the first membrane element 402 is located outside the first spacer element 413, and the second narrow circumferential gap 424 in the second membrane element 404 is also located outside the second spacer element 414.

[0131] As in Fig. 8b, the counter electrode structure 408 may comprise a further conductive layer 411, wherein the second conductive layer 411 is electrically insulated from the first conductive layer 410 by means of an insulating layer 415.

[0132] The second portion 402b of the first membrane element 402 is electrically coupled to the first conductive layer 410, for example, by means of a connection or wiring 422, and the second portion 404b of the second membrane element 404 is electrically connected to the second conductive layer 411, for example, by means of an electrical connection element or wiring 423. Furthermore, an optional electrical connection 430 may be provided between the first and second conductive layers 410, 411.

[0133] Furthermore, one or more (in Fig. 8b) which provide a mechanical coupling between the first and second membrane elements 402, 404, may also be electrically conductive for providing an electrical connection between the first and second membrane elements 402, 404 and in particular between the first sections 402a, 404a of the first and second membrane elements 402, 404.

[0134] Regarding the vacuum MEMS microphone used in the Fig. 8a-b, it should be noted that the different readout configurations for the MEMS device 100 shown in the Fig. 7a-d are applicable to the vacuum MEMS microphones 400, which are Fig. 8a-b are described.

[0135] With the exception of the specific segmentation of the counter electrode structure 108 of the MEMS device 100 and 200 (as shown in the Fig. 1-7) and the membrane elements 402, 404 of the MEMS device 400 (as shown in the Fig. 8a-b) are the properties, dimensions and materials of the elements of the MEMS device 400 (the Fig. 8a-b) with the elements of the MEMS device 100 or 200 (the Fig. 1-7). More specifically, in the figures and in the description, identical elements and elements having the same functionality and / or the same technical or physical effect are typically provided with the same reference numerals and / or with the same names, so that the description of these elements and their functionality as illustrated in the various embodiments are mutually interchangeable or can be applied interchangeably in different embodiments.

[0136] Moreover, substantially the same or (at least) comparable readout configurations for the MEMS device 100 and 200 described in the Fig. 1-7, and for the MEMS device 400 shown in the Fig. 8a-b. In comparison, for example, to the implemented readout configurations according to the Fig. 7a-d, for example, possible readout configurations of the MEMS device 400 in the Fig. 8a-b, for example, may involve (only) an inversion (or exchange) between the membranes and the counter electrode with respect to their respective connections to the reference potential V and the readout circuit.

[0137] For the MEMS device 400 in Fig. 8a, for example, the conductive layer 410 can be polarized, ie, provided with a reference potential V, whereby the first and second membrane elements 402, 404 (which are not electrically connected) can be read differently. Alternatively, the first and second membrane elements 402, 404 can be polarized, ie, provided with a reference potential V, whereby the conductive layer 410 can be read asymmetrically.

[0138] For the MEMS device 400 in Fig. 8b, the first and second membrane elements 402, 404 may be polarized, ie provided with a reference potential V, and may be electrically connected, whereby the first and second conductive layers 410, 411 (which are not electrically connected) may be read differently. Alternatively, for the MEMS device 400 in Fig.8b, the first and second conductive layers 410, 411 (which are not electrically connected) may be differently polarized, ie provided with different reference potentials V1, V2, wherein the first and second membrane elements 402, 404 (which may be electrically connected) may be read out asymmetrically.

[0139] Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

[0140] Furthermore, the scope of the present application is not intended to be limited to the specific embodiments of the process, machine, manufacture, composition of material, means, methods, and steps described in the specification. As one of ordinary skill in the art will readily recognize from the disclosure of the present invention, processes, machines, manufacture, compositions of material, means, methods, or steps now existing or later developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be used in accordance with the present invention.Accordingly, it is intended that the appended claims include within their scope such processes, such machines, such manufacture, such compositions of matter, such means, such methods, or such steps.

Claims

[1] MEMS device (100) comprising: a first membrane element (102), a second membrane element (104) spaced from the first membrane element (102), a low-pressure region (106) between the first and second membrane elements (102, 104), the low-pressure region (106) having a pressure that is less than an ambient pressure, and a counter electrode structure (108) comprising a conductive layer (110) that is at least partially arranged in the low-pressure region (106) or extends into the low-pressure region (106), wherein the conductive layer (110) comprises a segmentation (112) that provides electrical insulation between a first portion (110a) of the conductive layer (110) and a second portion (110b) of the conductive layer (110), wherein the first portion (110a) of the conductive layer (110) is a central portion of the conductive layer (110) and the second portion (110b) of the conductive layer (110) is an edge portion of the conductive layer (110), and wherein the second portion (110b) of the conductive layer (110) is electrically connected to the first membrane element (102) and to the second membrane element (104) by means of an electrical connection element (118, 120). [2] The MEMS device (100) of claim 1, wherein the segmentation (112) of the conductive layer (110) is a narrow circumferential gap (112) in the conductive layer (110). [3] The MEMS device (100) of claim 1 or 2, wherein the first membrane element (102) comprises a deflectable portion (102a) and a fixed portion (102b), wherein the second membrane element (104) comprises a deflectable portion (104a) and a fixed portion (104b), and wherein the first portion (110a) of the conductive layer (110) is disposed between the deflectable portion (102a) of the first membrane element (102) and the deflectable portion (104a) of the second membrane element (104). [4] MEMS device (100) according to one of claims 1 to 3, wherein the first and second membrane elements (102, 104) are mechanically coupled. [5] The MEMS device (100) of any one of claims 1 to 4, wherein the first and second membrane elements (102, 104) are electrically connected. [6] The MEMS device (100) of any one of claims 1 to 5, wherein one or more pillars (122) are mechanically coupled between the first membrane element (102) and the second membrane element (104). [7] The MEMS device (100) of any one of claims 1 to 6, wherein the pressure in the low pressure region (106) is substantially a vacuum. [8] The MEMS device (100) of any one of claims 1 to 7, wherein the low pressure region (106) is located within a sealed cavity formed between the first membrane element (102) and the second membrane element (104). [9] MEMS device (200) comprising: a first membrane element (102), a second membrane element (104) spaced from the first membrane element (102), a low-pressure region (106) between the first and second membrane elements (102, 104), the low-pressure region (106) having a pressure that is less than an ambient pressure, and a counter electrode structure (108) comprising a conductive layer (110) that is at least partially arranged in the low-pressure region (106) or extends into the low-pressure region (106), wherein the conductive layer (110) comprises a segmentation (112) that provides electrical insulation between a first portion (110a) of the conductive layer (110) and a second portion (110b) of the conductive layer (110), wherein the counter electrode structure (108) comprises a further conductive layer (210), wherein a further segmentation (212) provides electrical insulation between a first portion (210a) of the further conductive layer (210) and a second portion (210b) of the further conductive layer (210), and wherein the first portion (210a) of the further conductive layer (210) is electrically insulated from the first portion (110a) of the first conductive layer (110), and wherein the first portion (210a) of the further conductive layer (210) is a central portion of the further conductive layer (210), and wherein the second portion (210b) of the further conductive layer (210) is an edge portion of the further conductive layer (210), and wherein the second portion (110b) of the conductive layer (110) is electrically connected to the first membrane element (102) by means of an electrical connecting element, and wherein the second portion (210b) of the further conductive layer (210) is electrically connected to the second membrane element (104) by means of an electrical connecting element. [10] The MEMS device (200) of claim 9, wherein one or more pillars (122) are mechanically coupled between the first and second membrane elements (102, 104), and wherein the one or more pillars (122) are electrically conductive for providing mechanical and electrical coupling between the first and second membrane elements (102, 104). [11] The MEMS device (200) of claim 9 or 10, wherein the first membrane element (102) comprises a deflectable portion (102a) and a fixed portion (102b), wherein the second membrane element (104) comprises a deflectable portion (104a) and a fixed portion (104b), wherein the first portion (110a) of the conductive layer (110) faces the deflectable portion (102a) of the first membrane element (102) and wherein the first portion (210a) of the further conductive layer (210) faces the deflectable portion (104a) of the second membrane element (104). [12] The MEMS device (100) of any one of claims 9 to 11, wherein the segmentation (212) of the further conductive layer (210) is a narrow circumferential gap in the further conductive layer (210). [13] The MEMS device (100) of claim 12, wherein a first spacer element (113) is disposed between the first membrane element (102) and the conductive layer (110), wherein a second spacer element (114) is disposed between the second membrane element (104) and the further conductive layer (210), and wherein the narrow circumferential gap (112) in the conductive layer (110) is located outside the first spacer element (113) and wherein the narrow circumferential gap (212) in the further conductive layer (210) is located outside the second spacer element (114). [14] The MEMS device (200) of claim 12 or 13, wherein the narrow circumferential gap (112) in the conductive layer (110) is laterally offset with respect to a vertical projection from the narrow circumferential gap (212) in the further conductive layer (210). [15] The MEMS device (200) of any one of claims 12 to 13, wherein the narrow circumferential gap (112) in the conductive layer (110) and the narrow circumferential gap (212) in the further conductive layer (210) are arranged in a non-overlapping configuration. [16] The MEMS device (200) of any one of claims 12 to 15, wherein at least one of the narrow circumferential gap (112) in the conductive layer (110) and the narrow circumferential gap (212) in the further conductive layer (210) is completely filled with an insulating material. [17] The MEMS device (200) of any one of claims 6 to 8, wherein the one or more pillars (122) comprise an electrically insulating material for providing electrical isolation between the first membrane element (102) and the second membrane element (104). [18] MEMS device (100; 200) according to any one of the preceding claims, wherein the MEMS device is a MEMS microphone. [19] MEMS device (100; 200) according to any one of the preceding claims, further comprising: a circuit configured to process a signal generated by a deflection of the first membrane element and a deflection of the second membrane element. [20] MEMS device (100; 200) according to any one of the preceding claims, further comprising: a first voltage source (314) for biasing the first portion (110a) of the conductive layer (110) of the counter electrode structure (108) with a first voltage (V1), and a readout circuit (306) for reading out a signal generated by a deflection of the first membrane element (102) and a deflection of the second membrane element (104). [21] MEMS device (100; 200) according to any one of claims 9 to 20, wherein the MEMS device further comprises: a first voltage source (314) for biasing the first portion (110a) of the first conductive layer (110) with a first voltage V1, a second voltage source (316) for biasing the first portion (210a) of the second conductive layer (210) with a second voltage V2, and a readout circuit (306) for reading out a signal generated by a deflection of the first membrane element (102) and a deflection of the second membrane element (104). [22] The MEMS device (200) of claim 21, wherein the first portion (110a) of the first conductive layer (110) and the first portion (210a) of the second conductive layer (210) are not electrically connected, and wherein the first and second voltages V1, V2 are different. [23] MEMS device (100; 200) according to one of the preceding claims, further comprising: a reference voltage source (308) for biasing the first membrane element (102) and the second membrane element (104) with a reference potential and a readout circuit (306) for reading out a signal generated by a deflection of the first membrane element (102) and a deflection of the second membrane element (104). [24] MEMS device (100; 200) according to any one of the preceding claims, further comprising: a first voltage source (308) for biasing the first membrane element (102) with a first voltage V1, a second voltage source (314) for biasing the second membrane element (104) with a second voltage V2 and a readout circuit (306) for reading out a signal generated by a deflection of the first membrane element (102) and a deflection of the second membrane element (104). [25] MEMS device (400) comprising: a first membrane element (402), a second membrane element (404) spaced from the first membrane element (402), a low-pressure region (406) between the first and second membrane elements (402, 404), the low-pressure region (406) having a pressure that is less than an ambient pressure, and a counter electrode structure (408) comprising a first conductive layer (410) which is at least partially arranged in the low-pressure region (406) or extends into the low-pressure region (406), wherein the first membrane element (402) comprises a segmentation (412) providing electrical insulation between a first portion (402a) of the first membrane element (402) and a second portion (402b) of the first membrane element (402), and wherein the second membrane element (404) comprises a further segmentation (424) providing electrical insulation between a first portion (404a) of the second membrane element (404) and a second portion (404b) of the second membrane element (404), wherein the first portion (402a) of the first membrane element (402) is a center portion of the first membrane element (402) and wherein the second portion (402b) of the first membrane element (402) is an edge portion of the first membrane element (402), and wherein the first portion (404a) of the second membrane element (404) is a center portion of the second membrane element (404) and wherein the second portion (404b) of the second membrane element (404) is an edge portion of the second membrane element (404), and wherein the second portion (402b) of the first membrane element (402) and the second portion (404b) of the second membrane element (404) are electrically connected to the first conductive layer (410) by means of an electrical connecting element. [26] The MEMS device (400) of claim 25, wherein the segmentation (412) of the first membrane element (402) is a narrow circumferential gap in the first membrane element (402) and wherein the segmentation (424) of the second membrane element (404) is a narrow circumferential gap in the second membrane element (404). [27] The MEMS device (400) of claim 25 or 26, wherein one or more pillars (122) are mechanically coupled between the first membrane element (402) and the second membrane element (404). [28] The MEMS device (400) of any one of claims 25 to 27, further comprising: a reference voltage source for biasing the conductive layer of the counter electrode structure with a reference voltage, and a readout circuit for reading out a signal generated by a deflection of the first membrane element and a deflection of the second membrane element. [29] MEMS device (400) comprising: a first membrane element (402), a second membrane element (404) spaced from the first membrane element (402), a low-pressure region (406) between the first and second membrane elements (402, 404), the low-pressure region (406) having a pressure that is less than an ambient pressure, and a counter electrode structure (408) comprising a first conductive layer (410) which is at least partially arranged in the low-pressure region (406) or extends into the low-pressure region (406), wherein the first membrane element (402) comprises a segmentation (412) providing electrical insulation between a first portion (402a) of the first membrane element (402) and a second portion (402b) of the first membrane element (402), and wherein the second membrane element (404) comprises a further segmentation (424) providing electrical insulation between a first portion (404a) of the second membrane element (404) and a second portion (404b) of the second membrane element (404), wherein the first portion (402a) of the first membrane element (402) is a center portion of the first membrane element (402) and wherein the second portion (402b) of the first membrane element (402) is an edge portion of the first membrane element (402), and wherein the first portion (404a) of the second membrane element (404) is a center portion of the second membrane element (404) and wherein the second portion (404b) of the second membrane element (404) is an edge portion of the second membrane element (404), and wherein the counter electrode structure (408) comprises a further conductive layer (411) which is electrically insulated from the first conductive layer (410), and wherein the second section (402b) of the first membrane element (402) is electrically connected to the first conductive layer (410) by means of an electrical connection element, and wherein the second section (404b) of the second membrane element (404) is electrically connected to the further conductive layer (411) by means of an electrical connection element. [30] The MEMS device (400) of claim 29, wherein one or more pillars are mechanically coupled between the first membrane element (402) and the second membrane element (404). [31] The MEMS device (400) of claim 30, wherein the one or more pillars are electrically conductive for providing mechanical and electrical coupling between the first and second membrane elements (402, 404). [32] The MEMS device (200) of claim 30, wherein the one or more pillars comprise an electrically insulating material for providing electrical isolation between the first membrane element (402) and the second membrane element (404). [33] The MEMS device (400) of any one of claims 25 to 32, wherein a first spacer element is disposed between the first membrane element (402) and the counter electrode structure (408), wherein a second spacer element is disposed between the second membrane element (404) and the counter electrode structure (408), and wherein the narrow circumferential gap (412) in the first membrane element (402) is located outside the first spacer element and the narrow circumferential gap (424) in the second membrane element (404) is located outside the second spacer element. [34] The MEMS device (200) of any one of claims 25 to 33, wherein the MEMS device is a MEMS microphone. [35] The MEMS device (200) of any one of claims 25 to 34, further comprising: a circuit configured to process a signal generated by a deflection of the first membrane element (402) and a deflection of the second membrane element (404). [36] The MEMS device (400) of any one of claims 25 to 35, further comprising: a reference voltage source for biasing the conductive layer (410) of the counter electrode structure (408) with a reference voltage and a readout circuit for reading out a signal generated by a deflection of the first membrane element (402) and a deflection of the second membrane element (404). [37] The MEMS device (400) of any one of claims 25 to 36, wherein the MEMS device (400) further comprises: a first voltage source for biasing the first portion (402a) of the first membrane element (402) with a first voltage V1, a second voltage source for biasing the first portion (404a) of the second membrane element (404) with a second voltage V2, and a readout circuit for reading out a signal generated by a deflection of the first membrane element (402) and a deflection of the second membrane element (404). [38] The MEMS device (400) of claim 37, wherein the first and second membrane elements (402, 404) are not electrically connected and wherein the first and second voltages V1, V2 are different. [39] The MEMS device (400) of claim 37 or 38, wherein the second portion (402b) of the first membrane element (402) and the second portion (404b) of the second membrane element (404) are electrically connected to the conductive layer (410, 411) of the counter electrode structure (408). [40] A method for reading a MEMS device (100; 200) according to any one of claims 1 to 24, the method comprising: Providing a signal generated by a deflection of the first membrane element (402) and a deflection of the second membrane element (404). [41] The method of claim 40, further comprising: Biasing the first portion of the conductive layer of the counter electrode structure with a first voltage V1, and Reading the signal. [42] The method of claim 40, wherein the counter electrode structure comprises a first conductive layer and a second conductive layer, the method further comprising: Biasing the first portion of the first conductive layer with a first voltage V1, Biasing the first portion of the second conductive layer with a second voltage V2, and Reading the signal. [43] The method of claim 42, wherein the first portion of the first conductive layer and the first portion of the second conductive layer are not electrically connected and wherein the first and second voltages V1, V2 are different. [44] A method according to any one of claims 40 to 43, further comprising: Pre-tensioning the first membrane element and the second membrane element with a reference potential and Reading the signal. [45] A method according to any one of claims 40 to 44, further comprising: Prestressing the first membrane element with a first voltage V1, Biasing the second membrane element with a second reference potential V2, and Reading the signal. [46] A method for reading a MEMS device (400) according to any one of claims 25 to 39, the method comprising: Providing a signal generated by a deflection of the first membrane element and a deflection of the second membrane element. [47] The method of claim 46, further comprising: Biasing the conductive layer of the counter electrode structure with a reference voltage Vref, and Reading the signal. [48] ​​A method according to any one of claims 46 or 47, further comprising: Biasing the first portion of the first conductive layer with a first voltage V1, Biasing the first portion of the second conductive layer with a second voltage V2, and Reading the signal. [49] The method of claim 48, wherein the first portion of the first membrane element and the first portion of the second membrane element are not electrically connected and wherein the first and second voltages V1, V2 are different.

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