Micro-electromechanical sensor with reinforcing means between an electrode surface and a deflecting element

Abstract

The invention relates to a micro-electromechanical sensor (10) for measuring a surroundings variable (12) of the sensor surroundings (16), having at least one deflecting element (20) which can be deflected in the vertical direction (18) on the basis of the surroundings variable (12), at least one counter electrode (32), and at least one electrode surface (34) which is coupled to the deflecting element (20) and can move on the basis of the deflection of the deflecting element (20), thereby adjusting the electrode spacing (38) relative to the counter electrode (32), and which faces the counter electrode (32), wherein between the electrode surface (34) and the deflecting element (20) are reinforcing means (44) that extend in a first direction (48), which is perpendicular to the vertical direction (18), so as to alternate with at least one first exposed intermediate space (50) between the deflecting element (20) and the electrode surface (34) and in a second direction (52), which is perpendicular to the vertical direction (18) and the first direction (48), so as to alternate with at least one second exposed intermediate space (54) between the deflecting element (20) and the electrode surface (34) and connect the electrode surface (34) and the deflecting element (20) in spaced relation to each other in the vertical direction (18).

Description

[0001] Microelectromechanical sensor with stiffening element between electrode surface and deflection element

[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 environmental variable, comprising a membrane which is movable depending on the environmental variable, a self-supporting region spanning a cavity and an electrode which is held on the inside of the membrane by means of a stiffening structure.

[0005] Disclosure of the invention

[0006] According to the present invention, a microelectromechanical sensor with the features of claim 1 is proposed. This allows the deflection element to be stiffened while reducing the mass involved in the deflection. The electrode surface can move plane-parallel to the counter electrode while changing the electrode spacing. The natural frequency of the structure involved in the deflection can be increased. Furthermore, vibration damping can be reduced. The sensor can be constructed more cost-effectively and in a more space-saving manner.

[0007] The microelectromechanical sensor can also be designed as a microelectromechanical transducer and, in addition to measuring the ambient variable, can also actuate the deflection element depending on a voltage between the electrode and the counter electrode.

[0008] The sensor can be a pressure sensor or a microphone, or a combination of both. The sensor can measure the ambient variable capacitively. The sensor can comprise a microphone and / or a pressure sensor. The microphone and the pressure sensor can share the deflection element, or both can separately comprise such a deflection element. If the sensor is designed as a microphone, the stiffening means can reduce cross-sensitivity to ambient pressure.

[0009] 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 a differential pressure. The ambient variable can be a sound vibration.

[0010] The sensor can have an additional reference capacitance. The reference capacitance can be identical to the design and arrangement of the deflection element, the stiffening means, the electrode, and the counter electrode, but with the deflection element fixed relative to the counter electrode. This fixation can be achieved, for example, by connecting elements.

[0011] The sensor may comprise a substrate. The sensor may comprise multiple counter electrodes. The sensor may comprise multiple deflection elements. The deflection elements may be mechanically connected to one another and / or indirectly to the substrate, for example, via membrane segments.

[0012] The deflection element can comprise at least one deflection component. The deflection component can be a deflectable membrane or a cantilever beam. The deflection element can be constructed of polysilicon. The deflection element can be electrically connected to a ground potential. This can advantageously provide extensive electromagnetic shielding of all electrodes and the counterelectrode, the counterelectrodes, or all counterelectrodes.

[0013] The vertical direction may be a direction perpendicular to the main extension plane of the sensor.

[0014] The electrode surface can be rectangular, square, polygonal, round, oval or any other shape.

[0015] The sensor can have a cavity into which the deflection element can be deflected. The cavity can be designed as a recess in a substrate. The cavity can be delimited at least in sections by the deflection element. The stiffening means, the counter electrode(s), and the electrode surface or surfaces can be arranged in the cavity. The cavity can be filled with a fluid that is different from the sensor environment. A fluid pressure in the cavity can be lower than an ambient pressure of the sensor environment. This can effectively reduce thermal noise and squeeze film damping effects. The cavity can have a gas pressure of less than 10 mbar, in particular less than 1 mbar. The sensor can therefore have a higher signal-to-noise ratio.

[0016] The deflection element, in particular the deflection component, the stiffening means, and the electrode surface can be designed as a single piece or separately. The stiffening means can be constructed of polysilicon.

[0017] The stiffening means can be arranged symmetrically, in particular concentrically, to a center of the deflection element. The stiffening means can be spaced from a center of the deflection element with respect to the first and / or second direction. The stiffening means can be arranged in an edge region of the deflection element. This can influence the flexural rigidity of the deflection element.

[0018] The stiffening means can locally stiffen the deflection element with respect to bending loads during deflection. The stiffening means can increase the bending stiffness of the deflection element with respect to the deflection. This allows the deflection element to exhibit smaller deflection amplitudes. The electrode spacing can be reduced, thus increasing the measurement sensitivity of the sensor. The stiffening means can comprise a base plate. The electrode surface can be arranged on the base plate or formed by the base plate. The electrode surface can be designed in multiple parts, in particular interrupted by the intermediate spaces and / or connecting elements.

[0019] The stiffening means may comprise at least one stiffening element. The stiffening means may comprise a plurality of stiffening elements spaced apart from one another in the first and / or second direction. The spacing of the stiffening elements may form the gaps in the respective direction. The stiffening means may also comprise a stiffening element that integrally forms the gaps in the respective direction. The stiffening element may be a perforated plate or a beam structure.The key advantage of this design, consisting of stiffening elements with interspaces, is that, compared to a locally homogeneously thickened deflection component, it offers a better ratio of additional stiffening to additional mass, while also enabling reduced gas damping. This is because the residual fluid in the cavity between the electrode(s) and counterelectrode(s) can flow back and forth through recesses in the electrode surface / base plate into the rear interspaces. This allows for high natural frequency of the deflection element and high signal-to-noise ratio. In addition, the interspaces, in conjunction with the recesses in the electrode surface or base plate, can facilitate the removal of the sacrificial layer in the narrow electrode gap.

[0020] The electrode surface can be arranged so as to overlap the stiffening means with respect to the first and / or second direction. The electrode surface can completely cover the stiffening means with respect to the first and / or second direction. The electrode surface can protrude beyond the stiffening means with respect to the first and / or second direction. This allows for a higher capacitance with a simultaneously greater deflection, thus increasing the sensitivity of the sensor.

[0021] The electrode surface and the counterelectrode, or a counterelectrode surface of the counterelectrode, can be arranged at least in a central region of the deflection element with respect to the first and / or second direction, in particular spanning a center of the deflection element. The electrode surface and the counterelectrode, or counterelectrode surface, can be spaced from a center of the deflection element with respect to the first and / or second direction. The electrode surface can be arranged in an edge region of the deflection element with respect to the first and / or second direction.

[0022] The electrode spacing, i.e. the electrode gap, at zero deflection, i.e. at rest, of the deflection element can be less than 1 pm, in particular equal to or less than 0.5 pm.

[0023] The counter electrode can be movable relative to the electrode surface via a tilting element that can be tilted depending on the deflection of the deflection element. The maximum deflection in the central region of the deflection element can be translated into a tilting movement of the tilting element. The electrode surface and the counter electrode can be arranged in the edge region, which is in particular larger in area than the central region. This can increase the electrical capacitance or the change in capacitance upon deflection of the deflection element.

[0024] The first direction can be an x-direction and the second direction a y-direction in a Cartesian coordinate system. The first direction can be a radial direction and the second direction can be a circumferential direction in a polar coordinate system. The Cartesian coordinate system or the polar coordinate system can be oriented flatly parallel to the deflection element at zero deflection.

[0025] In a preferred embodiment of the invention, it is advantageous if the deflection element comprises a first deflection component and a second deflection component, which are arranged vertically spaced from one another. A fluid connection can be arranged between a surface of the first deflection component facing the sensor environment and a surface of the second deflection component facing away from the first deflection component. This can achieve pressure equalization between the two surfaces. The fluid connection can comprise at least one fluid channel. The fluid connection can be arranged outside or inside the stiffening means.

[0026] The cavity can be spanned between the first and second deflection components. In a lateral direction perpendicular to the vertical direction, the cavity can extend to an edge of the recess in the substrate.

[0027] The first and / or second deflection component may be rectangular, square, polygonal, round, oval or any other shape.

[0028] A preferred embodiment of the invention is advantageous in which a deflection of the first deflection component is coupled to a deflection of the second deflection component. This allows the measurement sensitivity of the sensor to be increased.

[0029] A preferred embodiment of the invention is advantageous in which the stiffening means comprise first stiffening means which are arranged between the electrode surface as the first electrode surface and the first deflection component and connect the first electrode surface to the first deflection component, and which further comprise second stiffening means which are arranged between the electrode surface or a second electrode surface and the second deflection component and connect the electrode surface or the second electrode surface to the second deflection component. The first stiffening means can stiffen the first deflection element in the first direction and / or the second direction. The second stiffening means can stiffen the second deflection element in the first and / or second direction. The stiffening means can stiffen the deflection element over the extension in the first and second directions, in particular biaxially.

[0030] In a specific embodiment of the invention, it is advantageous if the first stiffening means extend in the first direction exclusively alternating with at least the first gap, and the second stiffening means extend in the second direction exclusively alternating with at least the second gap, or vice versa. This allows the stiffening means to be designed more simply and advantageously reduces the mass involved in the deflection of the deflection element.

[0031] In an advantageous embodiment of the invention, the second deflection component is coupled to the first deflection component via at least one connecting element. The connecting element can be arranged inside or outside the region of the stiffening means with respect to the first and / or second direction.

[0032] The second deflection component can be coupled to the first deflection component via a plurality of connecting elements. The connecting elements can be arranged inside and outside the region of the stiffening means and / or inside or outside the region of the electrode surface or surfaces. The number of connecting elements outside the region of the stiffening means and / or electrode surfaces can be greater, preferably more than twice as large, than the number of connecting elements within the region of the stiffening means and / or electrode surfaces.

[0033] At least one connecting element can be directly connected to the first and second deflection components.

[0034] A preferred embodiment of the invention is advantageous in which the connecting element connects the first and second stiffening means to one another. The connecting element can engage directly with the stiffening means and the additional stiffening means.

[0035] The first and second deflection components can be connected to one another via at least one connecting element that is directly connected to the first and second deflection components, and at least one further connecting element that directly engages the first and second stiffening means. In a preferred embodiment of the invention, the stiffening means comprise at least one spacer element for spacing the electrode surface from the deflection element in the vertical direction. The spacer element can be spaced from the connecting element with respect to the first and / or second direction.

[0036] In an advantageous embodiment of the invention, the spacer element accommodates the connecting element. The spacer element can enclose the connecting element, for example, in the shape of a cylinder jacket.

[0037] In an advantageous embodiment of the invention, the stiffening means electrically insulate the electrode surface from the deflection element. This allows the electrode surface to be shielded from external electromagnetic, particularly high-frequency, inputs to the sensor and reduces parasitic capacitances. This allows the sensor's signal-to-noise ratio to be increased. The electrical connection to the electrode surface can be implemented via a freely suspended supply line.

[0038] Further advantages and advantageous embodiments of the invention emerge from the description of the figures and the illustrations.

[0039] Character description

[0040] The invention is described in detail below with reference to the figures. They show in detail:

[0041] Figure 1: A cross-section of a microelectromechanical sensor in a specific embodiment of the invention.

[0042] Figure 2: A cross-section of a microelectromechanical sensor in another specific embodiment of the invention.

[0043] Figure 3: A top view of stiffening agents in a respective special

[0044] Embodiment of the invention.

[0045] Figure 4: A top view and a cross section of stiffening means in another specific embodiment of the invention. Figure 5: A top view and cross sections of stiffening means in another specific embodiment of the invention.

[0046] Figure 6: A plan view and a cross section of stiffening means in another specific embodiment of the invention.

[0047] Figure 7: A top view and cross sections of stiffening means in another specific embodiment of the invention.

[0048] Figures 8 and 9: A cross section of a microelectromechanical sensor in a respective specific embodiment of the invention.

[0049] Figure 10: A section of a spatial cross-section of a microelectromechanical sensor in a further specific embodiment of the invention.

[0050] Figure 11: A section of the microelectromechanical sensor from Figure 6.

[0051] Figure 12: A section of a spatial cross-section of a microelectromechanical sensor in a further specific embodiment of the invention.

[0052] Figure 13: A cross-section of a microelectromechanical sensor in another specific embodiment of the invention.

[0053] Figure 1 shows a cross-section of a microelectromechanical sensor in a specific embodiment of the invention. The microelectromechanical sensor 10 shown in Figure 1 a) for measuring an environmental variable 12, for example, a sound vibration 14 of a sensor environment 16, comprises a deflection element 20 that can be deflected in a vertical direction 18 depending on the environmental variable 12. The deflection element 20 comprises a first deflection component 22 and a second deflection component 26 connected thereto via connecting elements 24. A cavity 27 is spanned in the vertical direction 18 between the first and second deflection components 22, 26. A deflection of the first deflection component 22 is coupled to a deflection of the second deflection component 26. The first and second deflection components 22, 26 are preferably designed as membranes 28 that are received on a substrate 30.A counter electrode 32 is arranged between the first and second deflection components 22, 26 with respect to the vertical direction 18. The counter electrode 32 is fixed relative to the substrate 30. The first and second deflection components 22, 26 are deflectable relative to the counter electrode 32.

[0054] An electrode surface 34 facing the counter electrode 32 is coupled to the first deflection component 22. The electrode surface 34, as the first electrode surface 36, is movable depending on the deflection of the first deflection component 22, while changing an electrode spacing 38 relative to the counter electrode 32, as the first counter electrode 40. The first electrode surface 36 and the first counter electrode 40 form an electrical first capacitance 42, which is variable depending on the deflection of the first deflection component 22.

[0055] Stiffening means 44 are arranged between the electrode surface 34 and the first deflection component 22, which stiffening means 46 extend in a first direction 48 perpendicular to the vertical direction 18, alternating with exposed first spaces 50 between the first deflection component 22 and the first electrode surface 36, and in a second direction 52 perpendicular to the vertical direction 18 and the first direction 48, alternating with exposed second spaces (not visible here) between the first deflection component 22 and the first electrode surface 36, and which connect the first electrode surface 36 to the first deflection component 22 at a distance from the first deflection component 22 in the vertical direction 18.

[0056] A second electrode surface 56 faces a second counterelectrode 58, which is formed by the first counterelectrode 40 or is at least mechanically connected to the counterelectrode 40, and is coupled to the second deflection component 26 by further second stiffening means 60 of the stiffening means 44. The second electrode surface 56 is movable relative to the second counterelectrode 58 depending on the deflection of the second deflection component 26, changing an electrode spacing 38. The second electrode surface 56 and the second counterelectrode 58 form a second electrical capacitance 62, which is variable depending on the deflection of the second deflection component 26.

[0057] Furthermore, the second stiffening means 60 are arranged between the second electrode surface 56 and the second deflection component 26, which stiffening means extend in the first direction 48 alternating with exposed first spaces 50 between the second deflection component 26 and the second electrode surface 56 and in the second direction 52 alternating with exposed second spaces (not visible here) between the second deflection component 26 and the second electrode surface 56 and which connect the second electrode surface 56 to the second deflection component 26 at a distance from the second deflection component 26 in the vertical direction 18.

[0058] The first and second stiffening means 46, 60 may each be designed in a lattice structure having the first spaces 50 and second spaces.

[0059] The first and second electrode surfaces 36, 56 are arranged with respect to the first and / or second direction 48, 52 at least in a central region 64 of the deflection element 20 and can span a center 66 of the deflection element 20.

[0060] Figure 1 b) shows the microelectromechanical sensor 10 from Figure 1 with a deflected deflection element 20, i.e., a deflected first and second deflection components 22, 26. Due to the deflection, the electrode spacing 38 of the second capacitor 62 is smaller than the electrode spacing 38 of the first capacitor 42. The first and second electrode surfaces 36, 56 are deflected plane-parallel with respect to the first and second counter electrodes 40, 58. This allows a relative capacitance change to be increased as a capacitance change normalized to a basic electrical capacitance and to be detected differentially capacitively.

[0061] Figure 2 shows a cross-section of a microelectromechanical sensor in another specific embodiment of the invention. The microelectromechanical sensor 10 has the first deflection component 22 and the second deflection component 26. The first stiffening means 44, 46 are connected to the first deflection component 22, and the second stiffening means 44, 60 are connected to the second deflection component 26.

[0062] The connecting elements 24 connect the first and second stiffening means 46, 60 directly to one another and thereby couple the first and second deflection components 22, 26. Optionally, further connecting elements not visible here can be arranged directly between the first and second deflection components 22, 26.

[0063] Figure 3 shows a plan view of the central region of the deflection element with stiffening means in a respective specific embodiment of the invention. The stiffening means 44 shown in Figure 3 a) on the deflection element 20 with the electrode surface 34 are square and, in particular, designed as a perforated plate 68. The stiffening means 44 are designed as first or second stiffening means and extend in the first direction 48 and the second direction 52, each alternately to exposed first and second spaces 50, 54. The first and second spaces 50, 54 are designed, in particular, as holes 70.

[0064] Figure 3 b) shows stiffening means 44 with the electrode surface 34 on the deflection element 20, which are designed as first or second stiffening means and which extend in the first direction 48 and the second direction 52, each alternating with free first and second spaces 50, 54. If the first and second directions 48, 52 are referenced to a Cartesian coordinate system, the stiffening means 44 extend in the x-direction and the y-direction alternating with the first and second spaces 50, 54. If the first and second directions 48, 52 are referenced to a polar coordinate system, the stiffening means 44 extend in the radial direction 72 and the circumferential direction 74 alternating with the first and second spaces 50, 54.

[0065] Figure 3 c) shows stiffening means 44 with electrode surface 34, which have first and second stiffening means 46, 60. The first stiffening means 46 are designed like the stiffening means shown in Figure 3 b). The second stiffening means 60 are circular in shape, alternating with circular-ring-shaped spaces.

[0066] Figure 4 a) shows a plan view of the electrode surface 34 with stiffening means 44 on the deflection element 20. The electrode surface 34 is formed on a base plate 94, which is fastened to the deflection element 20. Figure 4 b) shows the cross-section along AA from Figure 4 a). The electrode surface 34 is formed on the base plate 94. The base plate 94 is fastened to the deflection element 20 by spacer elements 84. The spacer elements 84 are spaced from one another, forming the first intermediate spaces and the second intermediate spaces 54 visible here. The base plate 94, together with the spacer elements 84, forms the stiffening means 44.

[0067] Figure 5 a) shows a plan view of the electrode surface 34 with stiffening means 44 on the deflection element 20. Figure 5 b) shows the cross section along AA from Figure 5 a), and Figure 5 c) shows the cross section along BB from Figure 5 a). As shown in Figure 5 a), the electrode surface 34 is formed on a perforated plate 68. The stiffening means 44 surround the perforated plate 68. As shown in Figure 5 b), the perforated plate 68 is connected to the deflection element 20, forming first gaps 50. As shown in Figure 5 c), the spacer elements 84 connecting the perforated plate 68 to the deflection element 20 also form the second gaps 54.

[0068] Figure 6 a) shows a top view of the first electrode surface 36 on the first deflection component 22. Figure 6 b) shows the cross section along AA from Figure 6 b). The first electrode surface 36 is bar-shaped and is attached to the first deflection component 22 via spacer elements 84 forming second gaps 54.

[0069] Figure 7 a) shows a plan view of a deflection element 20. Figure 7 b) shows the cross section along AA from Figure 7 a). The deflection element 20 comprises the first and second deflection components 22, 26. On the first deflection component 22, the first electrode surface 36 is bar-shaped and is fastened to the first deflection component 22 via spacer elements 84. The spacer elements 84 are assigned to first stiffening means 46. On the second deflection component 26, the second electrode surface 56 is bar-shaped and aligned perpendicular to the first electrode surface 36 and is fastened to the second deflection component 26 via spacer elements 84 that are spaced apart from one another to form second intermediate spaces 54. The spacer elements 84 are assigned to second stiffening means 60.

[0070] Figure 7 c) shows the cross-section along BB from Figure 7 a). The spacer elements 84 connecting the first electrode surface 36 to the first deflection component 22 are spaced apart from one another, forming the first gaps 50.

[0071] Figures 8 and 9 show a cross-section of a microelectromechanical sensor in a respective specific embodiment of the invention. The structure of the microelectromechanical sensor 10 in Figure 8 is similar to that of Figure 1 except for the following differences. The first and second deflection components 22, 26 have a fluid connection 76 that connects a surface 78 of the first deflection component 22 facing away from the cavity 27 to a surface 80 of the second deflection component 26 facing away from the cavity 27, thereby equalizing pressure between the surfaces 78, 80. The fluid connection 76 comprises a fluid channel 82, which is delimited and sealed, in particular, from the cavity 27.The first stiffening means 46 comprise a plurality of spacer elements 84 for spacing the first electrode surface 36 from the first deflection component 22 in the vertical direction 18, wherein the spacer elements 84 electrically insulate the first electrode surface 36 from the first deflection component 22. The second stiffening means 60 also comprise a plurality of spacer elements 84 for spacing the second electrode surface 56 from the second deflection component 26 in the vertical direction 18, wherein the spacer elements 84 electrically insulate the second electrode surface 56 from the second deflection component 26. The electrically insulating spacer elements 84 can shield the first and second electrode surfaces 36, 56 from external electromagnetic interference.

[0072] The microelectromechanical sensor 10 in Figure 9 comprises the deflection element 20 with the first and second deflection components 22, 26, which are connected to one another via connecting elements 24. The first electrode surface 36 and the second electrode surface 56, as well as the first stiffening means 46 and the second stiffening means 60, are arranged in an edge region 86 of the deflection element 20 with respect to the first direction 48 and spaced from a center 66 of the deflection element 20.

[0073] The counter electrode 32 is coupled to the deflection element 20 via a tilting element 90 that can be tilted about a tilting axis 88 and a central coupling element 92 connected thereto. A deflection of the deflection element 20 causes a tilting movement of the tilting element 90 and thus a movement of the counter electrode 32. As a result, the maximum deflection in the central region 64 of the deflection element 20 can be translated into a tilting movement of the tilting element 90 and a movement of the counter electrode 32. The first and second electrode surfaces 36, 56 arranged in the edge region 86 and the counter electrode 32 can be designed with a larger area than if arranged in the central region 64. As a result, the electrical capacitance or the change in capacitance upon deflection of the deflection element 20 can be increased.

[0074] The stiffening means 44 have electrically insulating spacer elements 84.

[0075] Figure 10 shows a sector-shaped section of a spatial cross-section of a microelectromechanical sensor in another specific embodiment of the invention. The microelectromechanical sensor 10 comprises the first deflection component 22 and the second deflection component 26 connected thereto via connecting elements 24. Figure 11 shows a section of the microelectromechanical sensor from Figure 10. The connecting elements 24 connect the first deflection component (not shown here) to the second deflection component 26. The first stiffening means 46 comprise spacer elements 84 that are spaced apart from one another in the first and second directions 48, 52 and alternate with first and second gaps 50, 54 in the first and second directions 48, 52. The first stiffening means 46 comprise a base plate 94 which has, on a side facing away from the first deflection component, the first electrode surface 36 which faces the first counter electrode 40.

[0076] The second stiffening means 60 comprise further spacer elements 84 complementary to the spacer elements 84 of the first stiffening means 46. The second stiffening means 60 comprise a further base plate 94 which, on a side facing away from the second deflection component 26, has the second electrode surface 56 which faces the second counter electrode 58.

[0077] The spacer elements 84 each accommodate the connecting elements 24 by enclosing the connecting elements 24 in the shape of a cylinder jacket.

[0078] Studies have shown that this setup significantly reduces cross-sensitivity to ambient pressure when measuring sound vibrations.

[0079] Figure 12 shows a section of a spatial cross-section of a microelectromechanical sensor in another specific embodiment of the invention. The microelectromechanical sensor 10 is similar to that in Figure 11 except for the following differences. The spacer elements 84 of the stiffening means 44 are arranged at a distance from the connecting elements 24. The spacer elements 84 are designed to space the first electrode surface 36 from the first deflection component (not shown here) and, together with the base plate 94, form the stiffening means 44. A recess 95 is provided in the base plate 94 and the first and second counter electrodes 40, 58 for the connecting elements 24, so that the connecting elements 24 can move freely relative to them.

[0080] Figure 13 shows a cross-section of a microelectromechanical sensor in another specific embodiment of the invention. The microelectromechanical sensor 10 can be designed as a combined microphone 96 and pressure sensor 98 and arranged with a reference capacitance 100 on a common substrate 30. The microphone 96 comprises the fluid connection 76 between the first deflection component 22 and the second deflection component 26. The connecting elements 24 connect the first and second deflection components 22, 26 to one another to couple the deflection. The first stiffening means 46 are arranged on the first deflection component 22, and the second stiffening means 60 are arranged on the second deflection component 26. The first electrode surface 36 forms the first capacitance 42 with the first counterelectrode 40, and the second electrode surface 56 forms the second capacitance 62 with the second counterelectrode 58.

[0081] The pressure sensor 98 is arranged adjacent to the microphone 96. This also has the deflection element 20 with a first and second deflection component 22, 26 and the first stiffening means 46 on the first deflection component 22 and the second stiffening means 60 on the second deflection component 26. No connecting elements are provided; the first and second deflection components 22, 26 can thus be deflected independently of one another. When the external ambient pressure changes, the capacitances therefore change in the same direction. The fluid pressure reaches the pressure sensor 98 through the fluid channel 82 in the microphone 96. There is no direct fluid connection to the substrate recess.

[0082] The reference capacitance 100 has the first and second capacitances 42, 62 corresponding to the pressure sensor 98 and the microphone 96, but with electrode surfaces 34 that cannot be deflected due to the connecting means 24. As a result, a reference capacitance 100 required for a Wheatstone bridge measurement in conjunction with the capacitances of the pressure sensor 98 can be formed.

Claims

Patent claims 1. Microelectromechanical sensor (10) for measuring an environmental variable (12) a sensor environment (16), comprising at least one deflection element (20) which can be deflected in a vertical direction (18) depending on the environmental variable (12), at least one counter electrode (32), at least one electrode surface (34) which is coupled to the deflection element (20) and which can be moved relative to the counter electrode (32) depending on the deflection of the deflection element (20) by changing an electrode spacing (38) and which faces the counter electrode (32), characterized in that stiffening means (44) are arranged between the electrode surface (34) and the deflection element (20),which extend in a first direction (48) perpendicular to the vertical direction (18) alternating with at least one free first gap (50) between the deflection element (20) and the electrode surface (34) and in a second direction (52) perpendicular to the vertical direction (18) and the first direction (48) alternating with at least one free second gap (54) between the deflection element (20) and the electrode surface (34) and which connect the electrode surface (34) and the deflection element (20) to one another at a distance in the vertical direction (18).

2. Microelectromechanical sensor (10) according to claim 1, characterized in that the deflection element (20) has a first deflection component (22) and a second deflection component (26) which are arranged spaced apart from one another in the vertical direction (18).

3. Microelectromechanical sensor (10) according to claim 2, characterized in that a deflection of the first deflection component (22) is coupled to a deflection of the second deflection component (26).

4. Microelectromechanical sensor (10) according to claim 2 or 3, characterized in that the stiffening means (44) comprise first stiffening means (44) which are arranged between the electrode surface (34) as the first electrode surface (36) and the first deflection component (22) and connect the first electrode surface (36) to the first deflection component (22) and which further comprise second stiffening means (60) which are arranged between the electrode surface (34) or a second electrode surface (56) and the second deflection component (26) and connect the electrode surface (34) or the second electrode surface (56) to the second deflection component (26).

5. Microelectromechanical sensor (10) according to claim 4, characterized in that the first stiffening means (46) extend in the first direction (48) exclusively alternating with at least the first intermediate space (50) and the second stiffening means (60) extend in the second direction (52) exclusively alternating with at least the second intermediate space (54) or vice versa.

6. Microelectromechanical sensor (10) according to one of claims 2 to 5, characterized in that the second deflection component (26) is coupled to the first deflection component (22) via at least one connecting element (24).

7. Microelectromechanical sensor (10) according to claim 4 or 5 and claim 6, characterized in that the connecting element (24) connects the first and second stiffening means (46, 60) to one another.

8. Microelectromechanical sensor (10) according to one of the preceding claims, characterized in that the stiffening means (44) have at least one spacer element (84) for spacing the electrode surface (34) from the deflection element (20) in the vertical direction (18).

9. Microelectromechanical sensor (10) according to claim 6 or 7 and claim 8, characterized in that the spacer element (84) receives the connecting element (24).

10. Microelectromechanical sensor (10) according to one of the preceding claims, characterized in that the stiffening means (44) electrically insulate the electrode surface (34) from the deflection element (20).

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