Microsensor device having at least one insulating layer between a sensor component and electrode

Abstract

The invention relates to a microsensor device (10) for measuring at least one environmental variable of a sensor environment (12), comprising a support element (14), a sensor element (18) having at least one sensor component (22) which can be deflected on the basis on the environmental variable and spans a cavity (20) at least in sections, at least one counter electrode (26) which is arranged in the cavity (20) and fixed relative to the support element (14), at least one electrode (32) which is arranged in the cavity (20) and which, with an electrode surface (36) opposite the counter electrode (26) in the vertical direction, forms an electrical measuring capacitance (30) with the counter electrode (26) on the basis of the deflection, wherein the electrode (32) is electrically insulated relative to the sensor component (22) and attached to the sensor component (22), by means of at least one insulating layer (34), which can be passed through by the majority of the electrode surface (36) of the electrode (32).

Description

[0001] Microsensor device with at least one insulating layer between sensor component and electrode

[0002] The invention relates to a microsensor device according to the preamble of claim 1.

[0003] State of the art

[0004] DE 102018222712 A1 describes a microsensor device as a capacitive pressure sensor. The microsensor device has a cavity above a substrate, which is spanned by a sensor component that can be deflected depending on the fluid pressure of the ambient medium. Within the cavity, an electrical measuring capacitance, dependent on the deflection of the sensor component, is arranged, comprising an electrode and a counter electrode, and an electrical reference capacitance that is independent of the deflection.

[0005] Disclosure of the invention

[0006] According to the present invention, a microsensor device with the features of claim 1 is proposed. This allows the sensor component to be electrically decoupled from the electrode, i.e., an electrical potential of the sensor component and an electrical potential of the electrode can be decoupled. Furthermore, parasitic stray fields in the measuring capacitance can be reduced. The microsensor device can exhibit greater measurement accuracy and reduced signal noise. The microsensor device can be more robust against external electromagnetic influences.

[0007] The microsensor device can be a microelectromechanical sensor device. The microsensor device can be a pressure sensor and / or microphone. The microsensor device can be a barometric pressure sensor. The microsensor device can be installed in a vehicle, watercraft, aircraft, robot, a mobile, stationary, or movable device, an industrial device, or a consumer end product. The pressure sensor can measure an absolute pressure of an ambient medium or a differential pressure between a pressure of one ambient medium and a pressure of a second medium. In a zero state, in particular at zero deflection, of the sensor component, the electrode surface can be congruent with a plane having the vertical direction as the normal. The electrode surface can be designed from a single contiguous segment or with multiple segments.

[0008] The ambient variable can be a fluid pressure, in particular an air pressure, of an ambient medium. The ambient medium can be air or a liquid, for example, water.

[0009] The carrier element can be a substrate, for example, an LGA substrate or a ceramic substrate. The carrier element can be made of silicon or glass. The carrier element can comprise or form a housing that accommodates the sensor element.

[0010] The cavity can be sealed from the sensor environment. The cavity can have a fluid pressure that differs from the sensor environment. The fluid pressure in the cavity can be lower than the lowest fluid pressure of the ambient medium to be measured. The cavity can have a vacuum.

[0011] The sensor element can measure the ambient variable capacitively, piezoelectrically, and / or piezoresistively. The sensor component, particularly in the form of a membrane, can be deflectable depending on the ambient variable. The sensor element can provide a measurement signal dependent on the deflection. The sensor component can have a predetermined electrical potential. The sensor component can be grounded.

[0012] The sensor element can be electrically connected to an electronic unit. The electronic unit can be an ASIC. The electronic unit can provide a sensor signal depending on the state of the sensor element, which in turn depends on the ambient variable. The sensor signal can be dependent on the measurement signal. The electronic unit can include an evaluation unit. The sensor element and the electronic unit can be arranged side by side or one above the other on a substrate.

[0013] A protective compound can be arranged at least above the sensor element, in particular on the sensor component, facing the sensor environment in the vertical direction. The sensor element can be attached to the electronics unit and / or the substrate. The sensor element can be connected to the electronics unit and / or the substrate in a form-fitting, material-fitting, and / or force-fitting manner. The sensor element can be adhesively bonded to the electronics unit and / or the substrate. The insulating layer can be made of silicon oxide, silicon nitride, in particular silicon-rich silicon nitride. The insulating layer can be completely flat on one or both sides. The insulating layer can be completely recess-free and gap-free in the continuous main part. The insulating layer can have a temperature-dependent dielectric constant. The insulating layer can be completely continuous, i.e., coherent and uninterrupted.The insulating layer can be interrupted at one or more points or be made up of multiple layer segments, whereby the majority of the entire insulating layer is continuous, i.e. uninterrupted. All layer segments covered by the electrode surface are assigned to the insulating layer. If there are multiple layer segments, the majority of the insulating layer is a contiguous, uninterrupted layer segment. At least two layer segments can have the same or different shape, dimensions and / or size. The deflection behavior of the sensor component can be influenced by the arrangement and design of the layer segments and the electrode built on them. The electrode can be divided into electrode segments according to the layer segments. The electrode segments can be directly electrically connected to one another or electrically separated from one another.

[0014] In addition to the insulating layer, the electrode can be electrically insulated from the sensor component by at least one further insulating layer that is continuous across the majority of the electrode surface, and can be attached to the sensor component. The further insulating layer and the insulating layer can be arranged vertically one above the other.

[0015] In a preferred embodiment of the invention, it is advantageous if the insulating layer is arranged vertically between the sensor component and the electrode. The insulating layer can be arranged in the region of the entire electrode surface. The insulating layer can fully cover the electrode surface. The insulating layer can extend beyond the electrode surface in terms of surface area. The area of ​​the insulating layer can be smaller, equal to, or larger than the electrode surface.

[0016] A preferred embodiment of the invention is advantageous in that, in addition to the electrode as the first electrode, a further second electrode is arranged, which, with an electrode surface which is vertically opposite the counter electrode as the first counter electrode and / or a further second counter electrode, forms a deflection-dependent electrical second measuring capacitance with the first counter electrode and / or the second counter electrode, depending on the deflection of the sensor component. The first and second electrodes can be directly electrically separated from one another. The first and second measuring capacitances can be directly independent of one another. However, the first and second measuring capacitances can be indirectly dependent on one another, in particular via an electrical circuit. A change in the first measuring capacitance can be at least electrically independent of a change in the second measuring capacitance.

[0017] The first and second measuring capacitances can be designed for the same or different measuring ranges, in particular pressure measuring ranges.

[0018] In a preferred embodiment of the invention, it is advantageous if the second electrode is electrically insulated from the sensor component and attached to the sensor component via the insulating layer as a first insulating layer or a further second insulating layer that is continuous over the majority of the electrode surface of the second electrode. A layer thickness of the first insulating layer and a layer thickness of the second insulating layer can be the same or different. The first and second insulating layers can be formed in one piece or separately from one another. The first and second insulating layers can be arranged adjacent to one another or separately from one another.

[0019] In a preferred embodiment of the invention, it is provided that the first electrode is attached to the insulating layer via first stiffening means and / or the second electrode via second stiffening means. The first stiffening means can have a stiffness, in particular related to the deflection of the sensor component, which differs from a stiffness of the second stiffening means, in particular related to the deflection of the sensor component. The second stiffening means can be designed to be stiffer or less stiff than the first stiffening means with respect to a deflection of the sensor component. For example, the first and second stiffening means can each comprise supports, wherein the supports of the second stiffening means are designed to be wider than the supports of the first stiffening means, at least in one lateral direction.This allows the deflection property of the sensor component, which depends on the fluid pressure of the sensor environment, to be adjusted locally.

[0020] The first measuring capacitance can be designed for a smaller pressure range and the second measuring capacitance for a larger pressure range, or vice versa. The first stiffening means can be arranged in a center of the sensor component and the second stiffening means in an edge region of the sensor component, or vice versa. As a result, the first measuring capacitance arranged in the center can be designed for measurement in a smaller pressure range, and the second measuring capacitance in the edge region can be designed for measurement in a larger pressure range.

[0021] In a specific embodiment of the invention, it is advantageous if the sensor element has an additional electrical capacitance for determining the type of medium present on the surface of the sensor component facing the sensor environment. The additional capacitance can be arranged by at least two electrodes on a surface of the sensor element facing the sensor environment. The additional capacitance can detect the presence of a liquid, for example, water, instead of a gas, for example, air, on the sensor component.

[0022] In a specific embodiment of the invention, it is advantageous if the electrode is electrically connected via at least one electrically conductive contact layer. The first and second electrodes can be electrically connected to one another via the contact layer. The first or second electrode can be electrically connected externally via the contact layer or a respective contact layer. The contact layer can be a semiconductor layer, in particular made of silicon or polysilicon.

[0023] In a preferred embodiment of the invention, the contacting layer is arranged on the insulating layer, facing the electrode with respect to the vertical direction, and is electrically separated from the sensor component by the insulating layer. The contacting layer can be arranged in the region of the entire electrode surface. The contacting layer can extend beyond the electrode surface in terms of its surface area. The surface area of ​​the contacting layer can be smaller, equal to, or larger than the surface area of ​​the insulating layer and / or the electrode surface.

[0024] In a specific embodiment of the invention, it is advantageous if, in addition to the measuring capacitance, an electrical reference capacitance independent of the ambient variable is arranged within the cavity, with a fixed reference electrode and reference counter electrode. The measuring capacitance and the reference capacitance can be electrically connected at least in a half-bridge circuit or as part of a full-bridge circuit.

[0025] In a specific embodiment of the invention, it is advantageous if, in addition to the first and second measuring capacitances and the reference capacitance, an electrical second reference capacitance independent of the ambient variable is arranged within the cavity as the first reference capacitance, with a fixed second reference electrode and second reference counter electrode. The first and second measuring capacitances and the first and second reference capacitances can be electrically connected in a full-bridge circuit.

[0026] In a preferred embodiment of the invention, the insulating layer has a temperature-dependent dielectric constant, and the contact layer and the sensor component form an additional electrical capacitance for measuring a temperature. The additional electrical capacitance can be a capacitive temperature sensor. The temperature can be that of the insulating layer and indirectly that of the sensor component and the ambient medium of the sensor environment.

[0027] Further advantages and advantageous embodiments of the invention emerge from the description of the figures and the illustration.

[0028] Character description

[0029] The invention is described in detail below with reference to the figure. It shows:

[0030] Figures 1 to 8 each show a microsensor device in a specific embodiment of the invention. Figure 1 a) shows a plan view of upper electrodes of a microsensor device 10, Figure 1 b) shows a cross-section of the microsensor device 10 along AA from Figure 1 a), and Figure 1 c) shows a cross-section of the microsensor device 10 along BB from Figure 1 a). As initially described below with reference to Figure 1 b), the microsensor device 10 is designed as a capacitive pressure sensor for measuring a fluid pressure of a fluid in a sensor environment 12, with a carrier element 14, here in particular a substrate 16, a sensor element 18 with a sensor component 22 which is deflectable depending on the fluid pressure in the sensor environment 12 and at least partially, here predominantly, spans a cavity 20, which sensor component is preferably a membrane 24.

[0031] Furthermore, a counter electrode 26 fixed relative to the carrier element 14 and an electrode 32 are arranged in the cavity 20, which forms an electrical measuring capacitance 30 with the counter electrode 26 via an electrode surface 36. The electrode surface 36 is arranged vertically opposite the counter electrode 26 and forms the deflection-dependent electrical measuring capacitance 30 with the counter electrode 26. The electrode 32 is electrically insulated from the sensor component 22 via an insulating layer 34, which is continuous over the majority of the electrode surface 36 of the electrode 32, and is fastened to the sensor component 22. The insulating layer 34 is arranged in the vertical direction 28 between the sensor component 22 and the electrode 32. The counter electrode 26 is arranged on the carrier element 14 via a further insulating layer 38.

[0032] As shown in Figure 1 c), the electrode 32 is electrically connected via at least one electrically conductive contact layer 40. The contact layer 40 is arranged on the insulating layer 34, facing the electrode 32 with respect to the vertical direction 28, and is electrically separated from the sensor component 22 by the insulating layer 34. As shown in Figure 1 a) and Figure 1 c), the contact layer 40 is led outward to electrically connect the electrode 32.

[0033] As shown in Figure 1 b), within the cavity 20, in addition to the measuring capacitance 30, there is arranged an electrical reference capacitance 42, which is independent of the ambient variable, with a fixed reference electrode 44 and reference counter electrode 46. As shown in Figure 1 a), the reference electrode 44 surrounds the electrode 32. As shown in Figure 1 b), the reference electrode 44 is connected to an edge 48 attached to the carrier element 14 or is designed as a single piece. The reference counter electrode 46 is arranged on the further insulating layer 38 on the carrier element 14. The reference electrode 44 and reference counter electrode 46 are fixed relative to the carrier element 14.

[0034] The electrode 32 and the reference electrode 44 form the upper electrodes in the vertical direction 28, a top view of which is shown in Figure 1 a). The counter electrode 26 and the reference counter electrode 46 form the lower electrodes in the vertical direction 28, which are opposite the upper electrodes in the vertical direction 28.

[0035] The insulating layer 34 preferably has a temperature-dependent dielectric constant and the contacting layer 40 and the sensor component 22 form an additional electrical capacitance 50 for measuring a temperature.

[0036] A first electrical input voltage can be applied to the electrode 32 and the reference electrode 44, and a first electrical output voltage can be applied to the counter electrode 26 and a second electrical output voltage can be applied to the reference electrode 44.

[0037] Figure 2 a) shows a top view of the vertically upper electrodes of a microsensor device 10, and Figure 2 b) shows a top view of the vertically lower electrodes of the microsensor device 10. As shown in Figure 2 a), in addition to the electrode 32 as the first electrode 32.1, a further second electrode 32.2 is arranged, which can be deflected relative to a second counter electrode 26.2 shown in Figure 2 b) depending on the deflection of the sensor component 22 and, together with the second counter electrode 26.2, forms a deflection-dependent electrical second measuring capacitance 30.2 alongside the measuring capacitance 30 as the electrical first measuring capacitance 30.1. In addition to the reference capacitance 42 as the electrical first reference capacitance 42.1, which is formed by the reference electrode 44 as the first reference electrode 44.1 and the reference counter electrode 46 shown in Figure 2 b) as the first reference counter electrode 46.1, an electrical second reference capacitance 42.2 which is independent of the ambient variable is formed by a fixed second reference electrode 44.2 and, as shown in Figure 2 b), a second reference counter electrode 46.2.

[0038] The first and second electrodes 32.1, 32.2, as well as the first and second reference electrodes 44.1, 44.2, form the upper electrodes shown in Figure 2 a). Figure 2 b shows a top view of the lower electrodes. The counterelectrode 26, as the first counterelectrode 26.1, and the first reference counterelectrode 46.1 are formed as a single piece and are arranged next to the second counterelectrode 26.2, which are formed as a single piece, and the second reference counterelectrode 46.2.

[0039] As shown in Figure 2 a), the second electrode 32.2 is electrically insulated from the sensor component 22 by the insulating layer 34 and is attached to the sensor component 22. The first and second electrodes 32.1, 32.2 are electrically separated from one another. A first electrical input voltage can be applied to the first electrode 32.1 and the second reference electrode 44.2, a second electrical input voltage can be applied to the second electrode 32.2 and the first reference electrode 44.1, a second electrical input voltage can be applied to the first counter electrode 26.1 and thus also to the first reference counter electrode

[0040] 46.1 an electrical first output voltage and at the second counter electrode

[0041] 26.2 and thus also at the second reference counter electrode 46.2, an electrical second output voltage can be applied. This allows a compact full-bridge circuit to be implemented. Figure 3 shows a cross-section of a microsensor device 10 in a further specific embodiment of the invention. The first electrode 32.1 is attached to the insulating layer 34 via first stiffening means 78, which are designed as one piece with the electrode surface 36 of the first electrode 32.1. The second electrode 32.2 is electrically separated from the first electrode 32.1 and attached to the insulating layer 34 via second stiffening means 80, which are designed as one piece with the electrode surface 36 of the second electrode 32.2. The first and second electrodes 32.1, 32.2 lie opposite the first and second counter electrodes 26.1, 26.2 in the vertical direction 28. The first and second counter electrodes 26.1, 26.2 are designed as one piece.

[0042] The second stiffening means 80 are designed to be stiffer than the first stiffening means 78 with respect to a deflection of the sensor component 22. For example, the first and second stiffening means 78, 80 each comprise supports 82, wherein the supports 82 of the second stiffening means 80 are wider than the supports 82 of the first stiffening means 78, at least in a lateral direction 84. This allows the deflection characteristic of the sensor component 22, which depends on the fluid pressure of the sensor environment 12, to be locally adjusted.

[0043] For example, the first measuring capacitance 30.1 can be designed for a smaller pressure range and the second measuring capacitance 30.2 for a larger pressure range.

[0044] An electrical first input voltage is applied to the first electrode 32.1 and the first reference electrode 44.1, an electrical second input voltage is applied to the second electrode 32.2 and the second reference electrode 44.2, an electrical first output voltage is applied to the first and second counter electrodes 26.1, 26.2 and an electrical second output voltage is applied to the first and second reference counter electrodes 46.1, 46.2.

[0045] The microsensor device 10 shown in cross section in Figure 4 comprises stiffer stiffening means in the center 86 of the sensor component 22 than in the edge region 88 of the sensor component 22. As a result, the first measuring capacitance 30.1 arranged in the center 86 can be designed for measurement in a smaller pressure range and the second measuring capacitance 30.2 in the edge region 88 can be designed for measurement in a larger pressure range.

[0046] Figure 5 a) shows a top view of the vertically upper electrodes of a microsensor device 10, Figure 5 b) shows a cross-section of the microsensor device 10 along AA from Figure 5 a), and Figure 5 c) shows a cross-section of the microsensor device 10 along BB from Figure 5 a). The structure of the microsensor device 10 is similar to that of Figure 1 except for the following differences. The contacting layer 40 of the electrode 32 is divided into several webs 90, which are held on a beam 92. The webs 90 are attached to the insulating layer 34 via stiffening means 72.

[0047] Figure 6 shows a cross-section of a microsensor device 10, which corresponds to that of Figure 1, specifically Figure 1c), except for the following differences. The sensor component 22 is multilayered, with a continuous first layer 68 facing the sensor environment 12 and a second layer 70 having a plurality of recesses 94 and formed integrally with the first layer 68, to which the insulating layer 34 is applied.

[0048] The microsensor device 10 in Figure 7, which shows a cross-section of the microsensor device 10, is similar to that in Figure 1, specifically to that in Figure 1c), except for the following differences. The contact layer 40 is multilayered, with a continuous first layer 68 facing the electrode 32 and a second layer 70 having a plurality of recesses 94 and integral with the first layer 68, which is applied to the insulating layer 34.

[0049] Figure 8 shows a microsensor device 10 which is similar to that in Figure 5, except for the following differences. Figure 8 a) shows a plan view of the upper electrodes, and Figure 8 b) shows a cross-section along AA from Figure 8 a). The sensor component 22 is divided by a trench 96 into an inner part 98, on which the electrode 32 is received via the insulating layer 34, and an outer part 100, which rests on the edge 48. The trench 96 can have any desired shape, for example a mutually alternating interdigital structure 102. The inner part 98 is preferably directly electrically separated from the outer part 100 and forms an additional electrical capacitance 104 with the outer part 100. This additional capacitance 104 can be used to measure the type of medium, including at least one property of the medium above the sensor component 22, for example a humidity level, a type of medium, for example water or air.Optionally, a material, for example polyimide for detecting humidity, water and / or carbon dioxide, can be applied to the additional capacitance 104, which material has a change in dielectric value when the medium in the sensor environment 12 changes.

Claims

Patent claims 1. A microsensor device (10) for measuring at least one environmental variable of a sensor environment (12), comprising a carrier element (14), a sensor element (18) with at least one sensor component (22) which can be deflected depending on the environmental variable and at least partially spans a cavity (20), at least one counterelectrode (26) arranged in the cavity (20) and fixed relative to the carrier element (14), at least one electrode (32) arranged in the cavity (20) which, with an electrode surface (36) opposite the counterelectrode (26) in the vertical direction (28), forms an electrical measuring capacitance (30) with the counterelectrode (26) which is dependent on the deflection, characterized in that the electrode (32) is electrically insulated from the sensor component (22) by means of at least one insulating layer (34) which is continuous over the majority of the electrode surface (36) of the electrode (32), and is fastened to the sensor component (22).

2. Microsensor device (10) according to claim 1, characterized in that the insulating layer (34) is arranged in the vertical direction (28) between the sensor component (22) and the electrode (32).

3. Microsensor device (10) according to claim 1 or 2, characterized in that in addition to the electrode (32) as the first electrode (32.1), a further second electrode (32.2) is arranged, which, with an electrode surface opposite the counter electrode (26) as the first counter electrode (26.1) or a further second counter electrode (26.2) in the vertical direction (28), forms a deflection-dependent electrical second measuring capacitance (58) with the first counter electrode (26.1) or the second counter electrode (26.2).

4. Microsensor device (10) according to claim 3, characterized in that the second electrode (32.2) is connected via the insulating layer (34) as a first insulating layer or a further second insulating layer which extends over the predominant part of the is continuous across the electrode surface (36) of the second electrode (32.2), is electrically insulated from the sensor component (22) and is attached to the sensor component (22).

5. Microsensor device (10) according to claim 3 or 4, characterized in that the first electrode (32.1) is attached to the insulating layer (34) via first stiffening means (78) and the second electrode (32.2) is attached to the insulating layer (34) via second stiffening means (80), wherein the first stiffening means (78) have a stiffness that differs from a stiffness of the second stiffening means (80).

6. Microsensor device (10) according to claims 3 to 5, characterized in that within the cavity (20), in addition to the measuring capacitance (30), an electrical reference capacitance (42) which is independent of the ambient variable is arranged as a first reference capacitance (42.1) with a fixed reference electrode (44) as a first reference electrode (44.1) and reference counter electrode (46) as a first reference counter electrode (46.1) and an electrical second reference capacitance (42.2) which is independent of the ambient variable is arranged with a fixed second reference electrode (44.2) and second reference counter electrode (46.2).

7. Microsensor device (10) according to one of the preceding claims, characterized in that the electrode (32) is electrically connected via at least one electrically conductive contact layer (40).

8. Microsensor device (10) according to claim 7, characterized in that the contacting layer (40) is arranged on the insulating layer (34) facing the electrode (32) with respect to the vertical direction (28) and is electrically separated from the sensor component (22) via the insulating layer (34).

9. Microsensor device (10) according to one of claims 7 or 8, characterized in that the insulating layer (34) has a temperature-dependent dielectric constant and the contacting layer (40) and the sensor component (22) form an additional electrical capacitance (50) for measuring a temperature.

10. Microsensor device (10) according to one of the preceding claims, characterized in that the sensor element (18) has an electrical Additional capacity (104) for determining the type of medium present on the surface of the sensor component (22) facing the sensor environment (12).

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