Micro-electromechanical sensor with tilting element and electrode in a cavity

Abstract

The invention relates to a micro-electromechanical sensor (10) for measuring a surroundings variable of the sensor surroundings (12), having at least one deflecting element (16) which can be deflected at least along a vertical direction (14) on the basis of the surroundings variable and which comprises a free region (24) that extends at least partly across a cavity (22) delimited from the sensor surroundings (12), at least one tilting element (26) which is coupled to the deflecting element (16) via coupling means (28) that have at least one coupling element (32) and which can be tilted about at least one tilt axis (30) on the basis of the deflection of the deflecting element (16), a counter electrode (40, 45, 46, 98), and at least one electrode (52, 62, 66, 96) which is coupled to the tilting element (26) and is positioned in the cavity (22) and which can move relative to the counter electrode (40, 45, 46, 98) on the basis of the tilting movement of the tilting element (26) and in the process adjusts the spacing between the electrode and the counter electrode (40, 45, 46, 98), wherein the tilting element (26) has a higher degree of flexural rigidity than the coupling element (32) at least in some parts.

Description

[0001] Microelectromechanical sensor with tilting element and electrode in cavity

[0002] The invention relates to a microelectromechanical sensor according to the preamble of claim 1.

[0003] State of the art

[0004] DE 10 2019 205 348 A1 describes a microelectromechanical sensor for measuring an ambient variable, comprising a membrane movable depending on the ambient variable, a cantilevered region spanning a cavity, and an electrode arranged within the cavity so as to be adjustable via a lever element. The electrode is coupled to the deflection element via the lever element to couple the deflection movement of the deflection element and the adjustment movement of the electrode.

[0005] Disclosure of the invention

[0006] According to the present invention, a microelectromechanical sensor with the features of claim 1 is proposed. This allows for more flexible electrode arrangement in the sensor. The sensor can be constructed in a more space-saving manner, be more sensitive, and be manufactured more cost-effectively. Furthermore, the measurement accuracy of the sensor can be increased, and the sensor can be made less sensitive to external influences, in particular electromagnetic interference and / or environmental influences, in particular particles. The electrical capacitance between the electrode and the counter electrode can be increased.

[0007] The sensor can be a pressure sensor or a microphone, or a combination of both. The sensor can measure the ambient variable capacitively.

[0008] The ambient variable can be a pressure, in particular the ambient pressure of a fluid in the sensor environment. The ambient variable can be static and / or dynamic. The pressure can be an absolute pressure or differential pressure. The ambient variable can be a sound vibration.

[0009] The cavity can be filled with a fluid different from the sensor environment. The fluid pressure in the cavity can be lower than the ambient pressure of the sensor environment. This can effectively reduce thermal noise and squeeze film damping effects. The cavity can be vacuum-filled. The cavity can have a gas pressure of less than 10 mbar, in particular less than 1 mbar. The sensor can then exhibit an increased signal-to-noise ratio.

[0010] The deflection element can comprise a membrane and / or a bending beam. The deflection element can be electrically connected to a ground potential. This can provide electromagnetic shielding of the electrical capacitances in the cavity. The sensor can have multiple deflection elements. The deflection elements can be mechanically coupled to one another, for example, via membrane segments.

[0011] The electrode and the counter electrode can form an electrical capacitance. The electrical capacitance can depend on the electrode distance between the electrode and the counter electrode. The ambient variable can at least be measured as a function of the capacitance.

[0012] The counter electrode can be arranged at a distance from the electrode and / or the deflection element with respect to the vertical direction. The counter electrode can be arranged in the cavity. The counter electrode can be arranged between the electrode and the deflection element with respect to the vertical direction. The counter electrode can be designed, in particular mainly, to be free-standing. The counter electrode can be arranged on a side of the electrode facing away from the deflection element with respect to the vertical direction. The counter electrode can be designed in multiple pieces and, with the at least one electrode, form several mechanically and electrically separate capacitances. This allows for maximization of the measurement capacitance and creates the possibility for low-noise, drift-stable differential-capacitive measurement signal acquisition.

[0013] Depending on the position of the tilting axis, the tilting element can implement a translation between the deflection of the deflection element and the movement of the electrode, and thus the change in the electrode spacing. This allows the movement of the electrode along the vertical direction to be amplified by a suitably selected lever ratio of the tilting element relative to the tilting axis, depending on the deflection of the deflection element.

[0014] The sensor can have multiple tilting elements. The electrode can be formed by multiple separate tilting elements that are coupled to the deflection element. The electrode and the tilting element can be structurally separate from one another or constructed as a single piece. The electrode and the tilting element can be firmly connected to one another, in particular by form-fitting, force-fitting, and / or material-locking. The electrode can preferably have a lower mass per electrode surface, in particular a smaller thickness, than the tilting element, which leads to a higher natural frequency and allows for greater temporal dynamics while simultaneously reducing vibration sensitivity. The electrode can be coupled to the tilting element, in particular be firmly connected or constructed as a single piece. The tilting element can be arranged so as to overlap the electrode at least in sections with respect to the lateral direction.This allows the electrode to be clamped to the tilting element, thereby mechanically stabilizing it. The tilting element can also be arranged next to the electrode in the lateral direction. The multiple tilting elements can have different or identical leverage ratios.

[0015] The tilting element can comprise at least one lever beam. The tilting element can be designed, for example, in a rod-shaped or beam-shaped configuration. The tilting element can comprise multiple beam arms. In particular, the tilting element can have a higher flexural rigidity in the vertical direction than the electrode and the driver spring. This can be achieved, for example, by selecting a thickness of the tilting element several times, in particular at least three times, the thickness of the electrode. In this way, the tilting element can mechanically stabilize the electrode, and unwanted low-frequency eigenmodes can be suppressed.

[0016] The tilting element can be mounted via at least one torsion spring to form the tilting axis. The tilting element can be tiltable against a restoring force of a torsion spring. The tilting axis can be located at an edge region of the tilting element and / or spaced from the edge region. The position of the tilting axis can be selected depending on the desired leverage between the deflection of the deflection element and the movement of the electrode. The tilting axis or torsion spring can be fixed to a lateral side wall of the cavity.

[0017] The tilting element can be spaced apart from the deflection element by a gap. If the sensor has an electrode in a central region of the sensor that can be moved by the deflection of the deflection element directly or indirectly via the tilting movement, this electrode can be spaced apart from the deflection element by a gap.

[0018] The sensor can have a substrate as a support element. The deflection element can be arranged directly or indirectly on the substrate. The counter electrode can be fixed relative to the substrate. The counter electrode can be attached to the substrate in a free-standing manner.

[0019] The vertical direction can be formed by a normal to a main extension plane of the substrate.

[0020] The sensor can be rectangular. The deflection element can be circular. The vertical direction can be an axial direction, and the lateral direction can be a radial direction or a circumferential direction. The first and second deflection components can be circular. The electrode can be shaped like a segment of a circle. The electrode can have multiple regions shaped like segments of a circle. The regions of the electrode can be spaced apart from one another. The tilting element can run primarily in the radial direction. The tilting element can have a width in the circumferential direction and / or in the axial direction that is smaller, preferably many times smaller, than a length in the radial direction.

[0021] The deflection element can be rectangular. The vertical direction and the lateral directions can be Cartesian directions. The first and second deflection components can be rectangular. The electrode can be rectangular. The electrode can have a plurality of rectangular regions. The regions of the electrode can be spaced apart from one another. The tilting element can extend primarily in the vertical direction or lateral direction. The tilting element can have a width in the vertical direction and at least one first lateral direction that is smaller, preferably a multiple smaller, than a length in a second lateral direction.

[0022] A length of the coupling element in the vertical direction can be greater than a width of the coupling element in a lateral direction perpendicular to the vertical direction. The length of the coupling element in the vertical direction can be greater than the widths of the coupling element in all lateral directions. The length to the width can be equal to or greater than 2, preferably greater than 3.

[0023] The coupling means can comprise at least one coupling element. The coupling means can effect a single point-like coupling between the deflection element and the tilting element or between multiple tilting elements. The coupling means can advantageously be arranged in a central region of the deflection element. As a result, the deflection of the deflection element can effect the greatest possible movement of the coupling means and the tilting element.

[0024] A lever arm length as the distance between the coupling element and the tilting axis to a lever arm length as the distance between the tilting axis and the electrode can influence the leverage between the movement of the coupling element and the movement of the electrode.

[0025] At least one coupling element can comprise or form a driver spring, a support, an anchor, a wall, a column, a hollow structure, and / or a strut. The tilting element can, at least in sections, have a higher flexural rigidity than the driver spring. This can be achieved, for example, by a smaller thickness, spring length, and spring shape of the driver spring. The lower flexural rigidity of the driver spring advantageously results in a lower flexural rigidity of the assembly comprising the deflection element, coupling means, and tilting element, which increases the sensitivity of the sensor. Advantageously, the driver spring and the electrode, and optionally the torsion spring, can be made from the same layered material, which simplifies the manufacturing process. The coupling means, preferably the coupling element and the driver spring, can be arranged on a side of the tilting element opposite the electrode with respect to the tilting axis.

[0026] The coupling element and the tilting element can be structurally separate from each other or designed as one piece.

[0027] At least one counter electrode can be spaced apart from the tilt axis and / or the coupling element(s) with respect to the lateral direction. The counter electrode(s) can, in particular, have recesses for this purpose. This can reduce parasitic capacitances.

[0028] In a preferred embodiment of the invention, it is advantageous if the deflection element has at least two deflection components spanning the cavity between them. The two deflection components can be spaced apart from one another in the vertical direction. The cavity can be spanned between the two deflection components with respect to the vertical direction.

[0029] The substrate may have a free area adjacent to at least one of the deflection components, for example a recess or through-opening, in which this deflection component can move, preferably along the vertical direction.

[0030] The deflection components can be coupled, preferably connected, to one another by connecting means. A deflection of one deflection component can cause a deflection of the other deflection component, and preferably also vice versa. The connecting means can comprise at least one connecting element. The connecting element can extend, in particular without contact, through recesses in the counter electrode and optionally in the electrode. The connecting element can be at least one column, support, spring, wall, hollow structure, and / or strut. Through the recesses for the connecting elements and optionally through additional recesses, gas exchange can advantageously take place and damping by the residual gas can be reduced.

[0031] A fluid connection can be present between a surface of one deflection component facing the sensor environment and the surface of the other deflection component facing away from it. The fluid connection can comprise at least one fluid channel. The fluid connection can be separated from the cavity, preferably sealed. The fluid connection can effect a quasi-static pressure equalization between one and the other surface. This can make the sensor's measurement signal less dependent on ambient pressure fluctuations. The sensor can be less sensitive to infrasound.

[0032] The deflection element may have more than two deflection components.

[0033] In a preferred embodiment of the invention, it is advantageous if the cavity has a deflectable central region spanned by the free region and an edge region laterally adjacent to the central region, wherein the counter electrode is arranged at least partially in the edge region. The counter electrodes can also be arranged at least partially, preferably in the edge region. The edge region can partially or completely surround the central region. This arrangement makes it possible to efficiently use the previously largely unusable edge region, particularly outside the free region of the sensor, which is also required for the mechanical stability and adhesive bonding of the sensor, if necessary in addition to the central region for detection. The deflection element can completely cover the central region. The deflection element can partially cover the edge region.The deflection element can be stiffened in the edge region. Deflection of the deflection element in the edge region can be omitted. The edge region can be stiffened, in particular by a substrate, a stiffening layer, a partially remaining sacrificial layer width, and / or by a different density or shape of the connecting elements, for example, rods, columns, struts, or the like. In this way, the freely movable central region and the essentially immovable edge region of the deflection element can be laterally fixed from the front side, without manufacturing tolerances playing a role in the production of a through-opening from the rear side of the substrate facing away from the deflection element.

[0034] The central area and the peripheral area can be inseparable from each other.

[0035] The torsion spring(s) of the tilting axis(es) can be arranged on connecting elements in the edge region, thereby reliably securing their position. These connecting elements can be designed, in particular, as columnar or wall-shaped elements. Such connecting elements, which extend from the outside to the inside in a particularly wall-shaped manner, can advantageously separate a stiffened edge region from a flexible central region.

[0036] The tilting element can extend from the central area into the edge area.

[0037] In an advantageous embodiment of the invention, it is provided that the electrode and / or counterelectrode is arranged at least in sections in the edge region. The electrode can be arranged entirely in the edge region. The electrode can also be arranged in sections in the central region. The electrode can be designed in multiple parts, in particular in several parts that are insulated from one another. One part can be arranged at least in sections in the edge region and / or in the central region. The counterelectrode can be arranged in sections or entirely in the edge region. The counterelectrode can also be arranged in sections in the central region. The counterelectrode can be designed in multiple parts, in particular in several parts that are insulated from one another. One part can be arranged at least in sections in the edge region and / or in the central region.The counter electrode can be mounted on a side wall and preferably extend cantilevered into the cavity. The side wall can be fixed to the substrate. The counter electrode can be connected to a connecting element, which stabilizes its spatial position.

[0038] In a preferred embodiment of the invention, it is advantageous if the tilting element has the higher flexural rigidity at least in a region between the electrode, in particular a self-supporting section of the electrode, and the coupling element, in particular the driver spring. The flexural rigidity can relate to the bending loads associated with the tilting movement. The flexural rigidity can relate to the vertical direction. The tilting element can have a higher flexural rigidity than the driver spring. The region of higher flexural rigidity of the tilting element can include at least the region of the tilting axis.

[0039] In an advantageous embodiment of the invention, the coupling means comprise at least one driver spring. The driver spring can be arranged at least partially, in particular completely, in the central region. The driver spring and the coupling element can be fastened to one another. Upon deflection of the deflection element, the bending preferably occurs in the softer driver spring, thereby reducing the stiffness of the deflection element, preferably with the deflection component or components and the tilting element, and enabling greater sensitivity of the sensor.

[0040] A ratio of a thickness of the tilting element to a thickness of the driver spring or electrode, in particular in each case with respect to the vertical direction, can be greater than or equal to 2, in particular greater than or equal to 5. A ratio of a thickness of the torsion spring to a thickness of the electrode, in particular in each case with respect to the vertical direction, can be greater than or equal to 1. A ratio of a thickness of the torsion spring to a thickness of the tilting element, in particular in each case with respect to the vertical direction, can be greater than 1, in particular 5. The torsion spring can be arranged between the coupling element and the electrode with respect to the lateral direction. These geometric relationships, on the one hand, enable tilting of the tilting element by the driver spring and, on the other hand, ensure that the flexural rigidity of the assembly comprising the deflection element and tilting element is not excessive. Overall, this increases the sensitivity of the sensor.

[0041] In a specific embodiment of the invention, it is advantageous if the electrode forms a first electrical capacitance with the counter electrode that can be varied by the tilting movement, and at least one second electrical capacitance that can be varied by the tilting movement is arranged at a distance from the first electrical capacitance along the lateral and / or vertical directions. The second capacitance can be arranged at a distance from the first capacitance along the tilting element. The second capacitance can preferably be evaluated separately from the first capacitance.

[0042] A further electrical capacitance may be arranged at a distance from the first and / or second capacitance along the lateral direction.

[0043] A distance between the electrode and the counter electrode of the first capacitance and a distance between the electrode and the counter electrode of the second capacitance may be equal at least at zero deflection of the deflection element.

[0044] The second capacitance can be formed between the electrode or a second electrode, on the one hand, and the counter electrode or a second counter electrode, on the other hand. The counter electrode and the second counter electrode can be assigned the same electrical potential or different electrical potentials. The first and second electrodes can be assigned the same electrical potential or different electrical potentials.

[0045] The second electrode can be arranged on the tilting element, on another such tilting element or on the deflection element and / or connected thereto.

[0046] In a specific embodiment of the invention, it is advantageous if, upon deflection of the deflection element, a change in the electrode spacing of the first capacitance is opposite to the change in the electrode spacing of the second capacitance. This allows a differential measurement to be carried out with respect to the tilting movement of the tilting element. For the differential, in particular differential-capacitive, measurement, it is advantageous if the electrode spacings of the capacitances involved are symmetrical. This can be achieved, on the one hand, by arranging an electrode vertically between two counter electrodes. This arrangement is particularly space-saving. The electrode spacings are defined by two sacrificial layer depositions, which places high demands on the manufacturing tolerances.Alternatively, two electrodes in a first plane and two counter electrodes in a second plane can be arranged vertically spaced from each other laterally on either side of the tilting axis of the tilting element. In this arrangement, it is particularly advantageous that the electrode spacing is determined by only one sacrificial layer deposition and is therefore intrinsically equal.

[0047] In a specific embodiment of the invention, it is advantageous if the tilting element is designed and arranged such that a total torque of the tilting element on the tilting axis is zero when the sensor, including the tilting element, is subjected to an acceleration. This can be achieved by a suitably optimized mass distribution on the tilting element. The total torque can be zero at least when the tilting element is subjected to accelerations parallel to the vertical direction. This can reduce the sensor's cross-sensitivity to accelerations such as gravitational, linear, and / or rotational accelerations.

[0048] In a further embodiment of the invention, it is advantageous if the sensor has a first deflection element, in particular above a substrate opening, for detecting a sound and / or relative pressure signal, and a second deflection element for detecting an absolute pressure signal. Media access to the second deflection element can be provided via a pressure equalization hole in the first deflection element. This arrangement protects the second deflection element from unwanted external influences.

[0049] The cavity defined by the deflection element can have a fluidic connection to a larger cavity, for example, formed in the substrate or another bonded substrate. This allows the preset pressure in the cavity to be maintained over its lifetime, even when materials outgas or gases diffuse in.

[0050] Further advantages and advantageous embodiments of the invention emerge from the description of the figures and the illustrations.

[0051] Character description

[0052] The invention is described in detail below with reference to the figures. They show in detail:

[0053] Figures 1 to 7: A respective cross section of a microelectromechanical sensor in a specific embodiment of the invention.

[0054] Figures 8 and 9: A respective spatial section of a microelectromechanical sensor in a further specific embodiment of the invention.

[0055] Figure 10: A top view of a microelectromechanical sensor in another specific embodiment of the invention. Figure 11: A cross-section of a microelectromechanical sensor in another specific embodiment of the invention.

[0056] Figures 1 to 7 show a respective cross-section of a microelectromechanical sensor in a specific embodiment of the invention. The microelectromechanical sensor 10 shown in Figure 1 for measuring an ambient variable of a sensor environment 12 comprises a deflection element 16 that can be deflected along at least one vertical direction 14 depending on the ambient variable. The ambient variable can be an ambient pressure p as the fluid pressure of the sensor environment 12 and / or a sound vibration, and the sensor 10 can be embodied as a pressure sensor and / or a microphone. The deflection element 16 comprises a first deflection component 20, preferably a membrane with a free area 24 that at least partially spans a cavity 22 delimited from the sensor environment 12.

[0057] A tilting element 26 is coupled to the deflection element 16, here to the first deflection component 20, via coupling means 28 and is mounted so as to be tiltable about at least one tilting axis 30 depending on the deflection of the deflection element 16. The coupling means 28 comprise at least one coupling element 32, here at least one armature 34 and a driver spring 36 connected thereto. The armature 34 connects the first deflection component 20 to the driver spring 36. The tilting element 26 comprises a stiffening region 38, through which the tilting element 26 has, at least in sections, a higher flexural rigidity than the driver spring 36 with respect to bending loads in the vertical direction 14 associated with the tilting movement of the tilting element 26.

[0058] A length L of the coupling element 32 in the vertical direction 14 is greater than a width B of the coupling element 32 in a lateral direction 42 perpendicular to the vertical direction 14.

[0059] A first counterelectrode 40 is fixed to a side wall 44 laterally delimiting the cavity 22, spaced apart from the coupling element 32 with respect to the lateral direction 42. A second counterelectrode 45 is designed separately from the first counterelectrode 40 or integrally with the first counterelectrode 40 and is fixed to the side wall 44. A third counterelectrode 46 is arranged on a substrate 48 opposite the first deflection component 20 with respect to the vertical direction 14. The substrate 48 is arranged as a carrier element 50 and accommodates at least the side wall 44. A first electrode 52 is coupled to the tilting element 26, arranged in the cavity 22, and movable depending on the tilting movement of the tilting element 26, changing an electrode distance from the first counterelectrode 40.The tilting element 26 has, at least in sections, in particular in the stiffening region 38, a higher flexural rigidity with respect to bending loads associated with the tilting movement of the tilting element 26 than the first electrode 52.

[0060] The first electrode 52 forms, together with the first counter electrode 40, an electrical first capacitance 58 that depends on the deflection of the deflection element 16 via a movement of the tilting element 26. A deflection of the deflection element 16 via the tilting movement of the tilting element 26 causes a change in an electrode distance 60 of the first capacitance 58.

[0061] The first capacitance 58 and all other electrical capacitances are shown here and in the following figures as an illustrative electrical circuit symbol.

[0062] A second electrode 62 is arranged in or on the first deflection component 20. The second electrode 62 forms a second electrical capacitance 64 with the second counter electrode 45.

[0063] A third electrode 66 is arranged on the tilting element 26 and is preferably formed integrally with the first electrode 52. The third electrode 66 forms a third electrical capacitor 68 with the third counter electrode 46.

[0064] The first, second, and third capacitances 58, 64, 68 each change depending on the deflection of the deflection element 16. The first and third electrodes 52, 66 change the first and third capacitances 58, 68 indirectly depending on the deflection of the first deflection component 20, namely via the tilting movement of the tilting element 26, and the second electrode 62 changes the second capacitance 64 directly via the deflection of the first deflection component 20.

[0065] Figure 2 shows a microelectromechanical sensor 10 which is similar to that in Figure 1 except for the following differences. The first capacitance 58 is formed between the first electrode 52 and the first counterelectrode 40. The second capacitance 64 is formed between a second electrode 62, which is arranged with the first electrode 52 on the tilting element 26, and the second counterelectrode 45. The first and second electrodes 52, 62 can be designed as one piece or separately from one another. The second capacitance 64 is arranged at a distance from the first capacitance 58 along the lateral direction 42 and, like the first capacitance 58, is variable depending on the tilting movement.A deflection of the deflection element 16 via the tilting movement of the tilting element 26 causes a change in the electrode spacing 60 of the first capacitance 58, which is opposite to the change in the electrode spacing 60 of the second capacitance 64. This enables a differential measurement of the deflection of the deflection element 16 with respect to the tilting movement of the tilting element 26. As previously mentioned, the electrode gap for both capacitances 58, 64 can be defined here with a single sacrificial layer deposition; at the same time, a differential-capacitive evaluation of the measurement signal is advantageously possible.

[0066] A third capacitor may be provided and thus optionally a third counter electrode 46, which may be arranged on the substrate 48 in a continuous manner or divided into at least two regions 70.

[0067] Figure 3 shows a microelectromechanical sensor 10, which corresponds to that of Figure 1 except for the following differences. The sensor 10 comprises the deflection element 16, which, in addition to the first deflection component 20, has a second deflection component 72. The cavity 22 is spanned between the first and second deflection components 20, 72 with respect to the vertical direction 14. The substrate 48 has a recess 74 or opening adjacent to the second deflection component 72, into which the second deflection component 72 can deflect.

[0068] The first and second deflection components 20, 72 are connected to each other by connecting means 76 in order to couple the deflection of the first deflection component 20 to a deflection of the second deflection component 72. The connecting means 76 comprise a plurality of connecting elements 78, which are preferably columnar in design here.

[0069] A fluid connection 86 is present between a surface 80 of the first deflection component 20 facing the sensor environment 12 and the surface 82 of the second deflection component 72 facing away from it, preferably in a central region 84 of the sensor 10 with respect to the lateral direction 42. The fluid connection 86 comprises at least one fluid channel 88, which is delimited, preferably sealed, from the cavity 22.

[0070] The cavity 22 has a central region 90 spanning the free region 24 and an edge region 92 laterally adjacent to the central region 90. The first and third electrodes 52, 66 and the first and third counterelectrodes 40, 46 are arranged at least partially in the edge region 92. Preferably, the tilt axis 30 is arranged here in the region of a transition between the central region 90 and the edge region 92.

[0071] A second capacitor may be provided and thus optionally a second counter electrode 45, which may be integral with the first counter electrode 40 or separate from the first counter electrode 40.

[0072] Figure 4 shows a microelectromechanical sensor 10 that is similar to that shown in Figure 3, except for the following differences. The first capacitance 58 is formed by the first electrode 52 on the tilting element 26 and a first counter electrode 40, which is cantilevered on the side wall 44, and the third capacitance 64 is formed by the third electrode 66 on the tilting element 26 and a third counter electrode 46 on or in the first deflection component 20. The first and third electrodes 52, 66 are arranged between the first counter electrode 40 and the deflection component 20 with respect to the vertical direction 14.

[0073] The tilting element 26 has the stiffening region 38 on a side facing away from the first deflection component 20.

[0074] Figure 5 shows a microelectromechanical sensor 10 similar to that shown in Figure 3, except for the following differences. The second capacitance 64 is formed by a second electrode 62 on the tilting element 26 and a second counterelectrode 45, which is arranged between the first deflection component 20 and the tilting element 26 with respect to the vertical direction 14. The second counterelectrode 45 can be formed integrally with the first counterelectrode 40 or separate from the first counterelectrode 40. As previously mentioned, the electrode gap for the first and second capacitances 58, 64 can be defined here with a single sacrificial layer deposition; at the same time, a differential-capacitive evaluation of the measurement signal is advantageously possible.

[0075] The third capacity can be provided optionally, but is not shown here.

[0076] Figure 6 shows a microelectromechanical sensor 10 that is similar to that shown in Figure 3, except for the following differences. The tilting element 26 has the stiffening region 38 on both sides. The first capacitance 58 is formed by the first electrode 52 on the tilting element 26 and the first counter electrode 40 arranged on the first deflection component 20. The second capacitance 64 is formed by the first electrode 52 on the tilting element 26 and the second counter electrode 46 arranged on the second deflection component 72. The deflection components 20, 72 are segmented into different conductive regions to keep parasitic capacitances as small as possible.

[0077] Figure 7 shows a microelectromechanical sensor 10 which is similar to that in Figure 6, except for the following differences. The first capacitor 58 is formed by the first electrode 52 on the tilting element 26 and a first counter electrode 40 which is cantilevered on the side wall 44. The third capacitor 68 is formed by the third electrode 66 on the tilting element 26 and a third counter electrode 46 which is also mounted on the side wall 44, but spaced from the first counter electrode 40 with respect to the vertical direction 14. The first and third electrodes 52, 66 are arranged between the first and third counter electrodes 40, 46 with respect to the vertical direction 14.

[0078] A second capacitance 64 is formed by a second electrode 62 on the first deflection component 20 and a second counter electrode 45. The first counter electrode 40 and the second counter electrode 45 can be formed as one piece or separately from one another.

[0079] A fourth capacitor 94 is formed by a fourth electrode 96 on the second deflection component 72 and a fourth counter electrode 98. The third counter electrode 46 and the fourth counter electrode 98 can be formed as one piece or separately from one another.

[0080] Figures 8 and 9 show a respective spatial sector section of a microelectromechanical sensor in another specific embodiment of the invention. The microelectromechanical sensor 10 shown in Figure 8 comprises the first deflection component (not shown here) and the cavity 22 between the first deflection component and the second deflection component 72. The connecting elements 78 connect the first deflection component and the second deflection component 72.

[0081] The second deflection component 72 is circular. The vertical direction 14 is an axial direction, and the lateral direction 42 is a radial direction.

[0082] The tilting element 26 is coupled to the deflection element 16, here to the first deflection component and the second deflection component 72, via the coupling means 28 to the coupling element 32, here to the armature 34 and the driver spring 36. The tilting element 26 is tiltably mounted about the tilt axis 30 depending on the deflection of the deflection element 16. The sensor 10 preferably comprises a plurality of tilting elements 26 spaced apart in the circumferential direction. Two tilting elements 26 can be connected to one another as an assembly 100. The tilting elements 26 can be spaced apart from one another circumferentially by an angle. The tilting elements 26 run primarily in the radial direction and have a width b in the circumferential direction that is smaller than a length I in the radial direction. The tilting elements 26 are, for example, rod-shaped or bar-shaped.

[0083] The driver springs 36 each have a lower flexural rigidity than the tilting element 26. The armature 34 connects the first deflection component and the second deflection component 72 to the driver spring 36. The first tilting element 102 of the assembly 100 is mounted via a first torsion spring 104 to form the first tilting axis 106. The second tilting element 108 of the assembly 100 is mounted via a second torsion spring 110 to form the second tilting axis 112. The first and second tilting elements 102, 108 are connected to one another in the region of the driver spring 36 and can each be tilted against a restoring force of the first and second torsion springs 104, 110.

[0084] The first and second torsion springs 104, 110 are each attached to a stiffening structure 111. The stiffening structure 111 is arranged on the substrate 48 and extends, in particular, as a radial beam from the side wall 44 to the receptacle of the respective torsion spring 104, 110. The respective torsion spring 104, 110 is rod-shaped and, in particular, has a vertical height to a radial width with a ratio of approximately 1.

[0085] The first electrode 52 is circular segment-shaped and connected to the tilting element 26. The third electrode 66 is integral with the first electrode 52. The first and third counterelectrodes 40, 46 are arranged vertically one above the other and accommodate the first and third electrodes 52, 66 between them. The first and third counterelectrodes 40, 46 are fixed to the side wall 44.

[0086] The respective tilting element 26 is preferably designed and arranged such that a total torque of the tilting element 26 on the tilting axis 30 is zero when an acceleration acts on the sensor 10. For this purpose, the mass densities of the tilting element 26 located on both sides of the torsion axis 30 are weighted and balanced by their distance from the tilting axis 30.

[0087] The sensor 10 in Figure 9 corresponds to that in Figure 8, except for the following differences. The first and second torsion springs 104, 110 are beam-shaped and arranged on both sides of the tilting element 26. A thickness of the respective torsion spring 104, 110 with respect to the vertical direction 14 can correspond to a thickness of the tilting element 26 with respect to the vertical direction 14.

[0088] Figure 10 shows a top view of a microelectromechanical sensor in another specific embodiment of the invention. The sensor 10 is round. Overall, two tilting elements 26 connected to each other by a cross strut 114 are combined in the cavity 22 to form an assembly 100, which can be tilted on both sides via tilting axes 30 and on which the circular segment-shaped first electrode 52 is arranged. The tilting axis 30 is mounted on a stiffening structure 111.

[0089] The masked first deflection component is connected to the second deflection component 72 via connecting elements 78. The connecting elements 78 comprise a central fluid channel 88, which is surrounded by a fixed second counter electrode 45.

[0090] The deflection element 16 is coupled to the tilting elements 26 via coupling means 28. The coupling means 28 comprise the coupling elements 32, here armatures 34 connected to the deflection element 16, and furthermore, driver springs 36 connected thereto.

[0091] Figure 11 shows a cross-section of a microelectromechanical sensor in another specific embodiment of the invention. A first deflection element 16a is arranged on the sensor 10 above a substrate opening 116 of a substrate 48 for detecting a sound or relative pressure signal, and a second deflection element 16b is arranged for detecting an absolute pressure signal. Media access to the second deflection element 16b can be provided via a fluid connection 86 in the first deflection element 16a. This arrangement protects the second deflection element 16b from unwanted external influences.

Claims

Patent claims 1 . Microelectromechanical sensor (10) for measuring an environmental variable of a sensor environment (12), comprising at least one deflection element (16) which is deflectable along at least one vertical direction (14) depending on the environmental variable and has a free area (24) which at least partially spans a cavity (22) delimited from the sensor environment (12), at least one tilting element (26) which is coupled to the deflection element (16) via at least one coupling element (32) and which can be tilted about at least one tilting axis (30) depending on the deflection of the deflection element (16), a counter electrode (40, 45, 46, 98), at least one tilting element (26) which is coupled to the tilting element (26), arranged in the cavity (22) and movable relative to the counter electrode (40, 45, 46, 98) depending on the tilting movement of the tilting element (26) and which has an electrode spacing (60) electrode (52, 62, 66, 96) changing to the counter electrode (40, 45, 46, 98),characterized in that the tilting element (26) has, at least in sections, a higher flexural rigidity than the coupling element (32), 2. Microelectromechanical sensor (10) according to claim 1, characterized in that the deflection element (16) has at least two deflection components (20, 72) spanning the cavity (22) between them.

3. Microelectromechanical sensor (10) according to claim 1 or 2, characterized in that the cavity (22) has a deflectable central region (90) spanned by the free region (24) and an edge region (92) laterally adjacent to the central region (90), wherein the counter electrode (40, 45, 46, 98) is arranged at least in sections in the edge region (92).

4. Microelectromechanical sensor (10) according to claim 3, characterized in that the electrode (52, 62, 66, 96) and / or counter electrode (40, 45, 46, 98) is arranged at least in sections in the edge region (92).

5. Microelectromechanical sensor (10) according to one of the preceding claims, characterized in that the coupling element (32) comprises a driver spring (36).

6. Microelectromechanical sensor (10) according to claim 5, characterized in that the tilting element (26) has, at least in sections, a higher flexural rigidity than the driver spring (36).

7. Microelectromechanical sensor (10) according to claim 6, characterized in that the tilting element (26) has the higher flexural rigidity at least in a region between the electrode (52, 62, 66, 96) and the driver spring (36).

8. Microelectromechanical sensor (10) according to one of the preceding claims, characterized in that the electrode (52, 62, 66, 96) with the counter electrode (40, 45, 46, 98) forms an electrical first capacitance (58) which is variable by the tilting movement of the tilting element (26), to which at least one electrical second capacitance (64) which is variable by the tilting movement is arranged at a distance along the lateral direction (42) and / or vertical direction (14).

9. Microelectromechanical sensor (10) according to claim 8, characterized in that upon a deflection of the deflection element (16), a change in the electrode spacing (60) of the first capacitor (58) is opposite to the change in the electrode spacing (60) in the second capacitor (64).

10. Microelectromechanical sensor (10) according to one of the preceding claims, characterized in that the tilting element (26) is designed and arranged such that a total torque of the tilting element (26) on the tilting axis (30) is zero when an acceleration acting on the sensor (10) including the tilting element (26) is applied.

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