Microelectromechanical sensor arrangement, method for operating a sensor arrangement and method for determining a correction value

Abstract

The invention relates to a microelectromechanical sensor arrangement (10) comprising - a sensor unit (30) configured to detect an external physical stimulus via a deflection of a movable structure (3), wherein the movable structure (3) is arranged within a cavity (31) of the sensor unit (30); and - a control and evaluation unit (30) configured to determine a sensor value based on the detected deflection of the movable structure (3). The cavity (31) of the sensor unit (30) is bounded by a planar housing component of the control and evaluation unit (20), the housing component (21) having an electrode (200, 200a, 200b) that can be subjected to a voltage (V). The control and evaluation unit (20) is further configured to vary a voltage (V) applied between the at least one electrode (200, 200a, 200b) and the movable structure (3) in order to compensate for a surface charge effect. The invention further relates to a method for operating the sensor arrangement (10) and a method for determining a correction value (TCO, TCOsc, DACCT0, DACCT1) for compensating the surface charge effect.

Description

[0001] The invention relates to a microelectromechanical sensor arrangement, such as an inertial, pressure, or acceleration sensor arrangement, and to a method for operating such a sensor arrangement, in particular for compensating for a surface charge effect. The invention further relates to a method for determining a correction value, in particular a temperature-dependent one, for compensating for a surface charge effect in such a sensor arrangement. State of the art

[0002] Micromechanical sensors, such as inertial sensors, pressure sensors, or acceleration sensors, are often designed as capacitive sensors with movable structures. The movable structure of a capacitive acceleration sensor can, for example, be designed as an asymmetric rocker. A microelectromechanical acceleration sensor with a movable structure designed as an asymmetric rocker is described, for example, in EP 0 773 443 A1.

[0003] Methods for temperature compensation in microelectromechanical sensors are generally known from, for example, DE 10 2019 217 333 A1 or DE 10 2021 204 615 A1. Disclosure of the invention

[0004] The object of the invention is to compensate or at least partially reduce the impact of a surface charge effect in a microelectromechanical sensor arrangement.

[0005] The above-mentioned object is achieved by the subject matter of the independent claims. Advantageous embodiments of the invention are specified in the dependent claims.

[0006] According to a first aspect of the invention, a microelectromechanical sensor arrangement is provided, which comprises a sensor unit and a control and evaluation unit. The sensor unit is designed to detect an external physical stimulus via a deflection of a movable structure, wherein the movable structure is arranged within a cavity of the sensor unit. The control and evaluation unit is designed to determine a sensor value based on the detected deflection of the movable structure. The cavity of the sensor unit is delimited by a planar housing component of the control and evaluation unit, which has at least one electrode to which a voltage can be applied. The control and evaluation unit is further designed to vary a voltage applied between the at least one electrode and the movable structure in order to compensate for a surface charge effect.

[0007] The sensor arrangement makes it possible to measure and compensate for a surface charge effect by applying a voltage to the electrode. To compensate for the surface charge effect, the voltage applied between the electrode and the movable structure is varied.

[0008] In possible embodiments, the planar housing component of the control and evaluation unit is connected to a housing of the sensor unit by wafer bonding, in particular eutectic bonding. The control and evaluation unit is typically implemented as an ASIC chip, which determines corresponding sensor values ​​based on the detected deflection. Since such ASIC chips are typically manufactured using a CMOS process for circuit technology and not a process suitable for microelectromechanical components, it is advisable to bond the control and evaluation unit to the sensor unit after production. Such bonding of the components can create interfaces with stationary surface charges, which can be compensated using the sensor arrangement according to the invention.

[0009] Preferably, at least two voltage-sensitive electrodes are provided on the housing component of the control and evaluation unit. In this case, the control and evaluation unit is preferably configured to vary the voltages applied in pairs between each of the electrodes and the movable structure in order to compensate for the surface charge effect. This allows, in particular, the influence of an inhomogeneous surface charge density on the movable structure to be determined more precisely and compensated for more effectively.

[0010] In advantageous embodiments, the movable structure of the sensor unit is designed, for example, as a deflectable, in particular asymmetric, rocker, which is adjustably mounted about a torsion axis running parallel to a main extension plane of the sensor arrangement. At least two of the electrodes are arranged in a lateral plane parallel to the main extension plane on opposite sides of the torsion axis, particularly preferably symmetrically to the torsion axis. In movable structures designed as asymmetric rockers, even comparatively homogeneously distributed surface charges can cause a torque of the movable structure about the torsion axis, since an asymmetric rocker, due to its design, can typically have a smaller distance from a layer with stationary charges in the area of ​​the larger mass than in the area of ​​the smaller mass.The influence of surface charges on the moving mass can be more accurately measured and more effectively compensated by arranging electrodes on opposite sides of the torsion axis.

[0011] According to a second aspect of the invention, a method for operating such a microelectromechanical sensor arrangement is provided, wherein a sensor value is determined based on a detection of the deflection of the movable structure, during which detection the at least one electrode is subjected to a correction voltage that compensates for the surface charge effect. The voltage application is controlled, for example, during operation of the sensor arrangement such that a predetermined voltage difference, which effectively compensates for the surface charge effect and corresponds to the correction voltage, is present between the electrode and the movable structure. In preferred embodiments, the control takes place in particular with respect to a second voltage applied to the movable structure, the voltage level of which can vary for the capacitive detection of the deflection.

[0012] The correction voltage can be determined capacitively before commissioning or during operation of the sensor arrangement.

[0013] Preferably, the correction voltage is determined based on a detection of the deflection of the movable structure in the absence of an external physical stimulus, for example, as part of a component-specific reference measurement after completion of the sensor arrangement consisting of the aforementioned sensor unit with the associated control and evaluation unit. In such a measurement, the voltage applied between the at least one electrode and the movable structure is varied to determine the influence of the surface charges on the detected deflection.

[0014] In one possible embodiment, the correction voltage is determined by determining a peak of the deflection detected as a function of the voltage. The voltage corresponding to the peak of the detected deflection is a measure, in particular, of the effective electrostatic influence of the surface charges on the movable structure and thus also represents a measure of the correction voltage that compensates for this influence.

[0015] According to a third aspect of the invention, a method is provided for determining a correction value for compensating the surface charge effect in the micromechanical sensor arrangement described above. The correction value is determined based on detecting the deflection of the movable structure in the absence of an external physical stimulus, wherein a voltage applied between the at least one electrode and the movable structure is varied.

[0016] Preferably, the voltage corresponding to a peak of the detected deflection is determined when determining the correction value. The voltage corresponding to the peak of the detected deflection is a measure, in particular, of the effective electrostatic influence of the surface charges on the movable structure and thus also represents a correction value for a sensor value. The sensor value, which measures, for example, the magnitude of a physical stimulus, can thus be digitally corrected for the influence of the surface charge effect.

[0017] In a further development, for temperature-dependent compensation of the surface charge effect, a first correction value is determined at a first operating temperature and a second correction value at a second operating temperature. The temperature-dependent correction value is preferably formed as a function of the first and second correction values ​​and the first and second operating temperatures.

[0018] Further details and advantages of the invention are explained in more detail below with reference to the exemplary embodiments illustrated in the drawings. They show: Fig. 1 and Fig. 2 cross-sectional views of an acceleration sensor; Fig. 3 a sensor arrangement with control and evaluation unit in a schematic cross-sectional view; Fig. 4 shows a sensor arrangement according to a first embodiment in a schematic cross-sectional view; Fig. 5 shows a sensor arrangement according to a second embodiment in a schematic cross-sectional view; Fig. 6 a characteristic curve which shows, by way of example, the dependence of the deflection of the movable structure of the sensor arrangement on an applied voltage; Fig. 7 a diagram showing the course of a correction value for compensating a temperature-dependent surface charge effect; Fig. 8 is a schematic block diagram illustrating a method for operating the sensor arrangement or a method for determining a correction value for compensating a surface charge effect.

[0019] Identical or corresponding elements are provided with the same reference symbols in all drawing figures.

[0020] Fig. 1 and Fig. 2 shows an example of an acceleration sensor 1 in cross-section. The acceleration sensor 1 is designed to detect a measurement signal that is generated as a function of an external physical stimulus acting on the movable structure. The capacitive acceleration sensor 1 shown is particularly configured to detect an acceleration or acceleration component oriented perpendicular to a wafer or a flat substrate 2 (z-direction) as an external physical stimulus and to assign a corresponding sensor value to the detected acceleration. An evaluation unit (not shown in detail) is typically provided for this purpose. To detect the external physical stimulus, a movable structure 3 designed as an asymmetric rocker is adjustably arranged above the substrate 2. The movable structure 3 is connected via at least one torsion spring 4 to an armature 5, which is fixedly arranged on the substrate 2.The torsion spring 4 extends along a torsion axis 50, about which the movable structure 3 designed as a rocker is adjustable, wherein the torsion spring 4 provides a resilient restoring force of the movable structure 3.

[0021] The movable structure 3 comprises a first mass 7a arranged on a first side of the torsion axis 50 and a second upper mass 7b arranged on the second side of the torsion axis 50. Due to an additional mass 8, the second mass 7b can be larger than the first mass 7a.

[0022] Two measuring electrodes 9a, 9b are arranged opposite the movable structure and fixedly attached to the substrate 2. The sensor principle of the acceleration sensor is based on a spring-mass system, in which the movable structure 3 forms two plate capacitors with the measuring electrodes 9a and 9b fixed to the substrate 2. The measuring electrodes 9a and 9b are arranged with respect to the movable structure 2 in such a way that the deflection of the movable structure 3, in particular with respect to the substrate 2, can be determined by evaluating a first capacitance between the first measuring electrode 9a and the movable structure 2 and a second capacitance between the second measuring electrode 9b and the movable structure 2.

[0023] Fig. 2 shows a cross section through the acceleration sensor of the Fig. 1 to illustrate its functionality. If the acceleration sensor learns how Fig. 2, an acceleration in the z-direction 1000, the movable structure 3 is deflected about the torsion axis 50 due to the additional mass 8 and adjusted so that a first average distance d1 between the movable structure 3 and the first measuring electrode 9a increases and a second average distance d2 between the movable structure 3 and the second measuring electrode 9b decreases.

[0024] The changes in the capacitances of the two capacitors formed by the movable structure 3 and the measuring electrodes 9a and 9b, which correspond to the changes in the distances d1 and d2, can then be evaluated to determine or determine the applied acceleration. Since methods for evaluating capacitance changes are known from the prior art, they will not be discussed further here. Such methods are typically implemented in a control and evaluation unit that determines corresponding sensor values ​​based on the detected deflection.

[0025] The movable structure of microelectromechanical sensors generally responds to surface charge effects, which can be caused, for example, by material layers with stationary charges, exerting an electrostatic force on the movable structure. This typically generates an offset shift that can exhibit a strong temperature dependence. Compensation for the temperature-dependent component of the offset cannot generally be achieved by simply calibrating the sensor at a given temperature.

[0026] Fig. Figure 4 shows a schematic cross-sectional view of a microelectromechanical sensor arrangement 10 with a control and evaluation unit 30, which is implemented, for example, in an ASIC chip. The sensor arrangement 10 has a sensor unit 30 with a cavity 31 in which a Fig. 1, a movable structure 3 (not shown in detail) is arranged. The sensor unit 30 with the movable structure 3 is typically manufactured using a process suitable for MEMS structures, which is generally incompatible with the CMOS processes used to manufacture circuitry components, such as ASIC chips or the like. The sensor unit 30 is therefore preferably connected to the associated control and evaluation unit 20 at the end of the production line and is typically inseparably connected, for example by wafer bonding, in particular eutectic bonding. In the example shown, a flat housing component 21 of the control and evaluation unit 30 is connected in an edge-side contact region 23 to a housing 32 of the sensor unit 30 by eutectic bonding.Interfaces, which arise particularly during bonding, can be occupied by partially stationary charges which exert an electrostatic force on the adjacent movable structure 3.

[0027] Fig. 3 shows a sensor arrangement 10 in which the control and evaluation unit 20 and the sensor unit 30 are arranged stacked one above the other in a z-direction 1000 perpendicular to the main extension plane of the sensor arrangement 10. Deviations from this are possible; in particular, in alternative embodiments, the control and evaluation unit 20 can be arranged above or below the sensor unit 30 in the z-direction 1000.

[0028] Fig. 4 shows a sensor arrangement 10 according to a first exemplary embodiment in a cross-sectional view. The flat housing component 21 of the control and evaluation unit 20, which defines the cavity 31 of the sensor unit 30, has an electrode 200 to which a voltage can be applied. In an equivalent embodiment, the housing component 21 can itself be configured to be subjected to a voltage, for example, by metallization in certain areas. By applying a first voltage Vcap to the electrode 200, a voltage V present between the electrode 200 and the movable structure 13 can be specified and varied.

[0029] The voltage application to the electrode 200 can in particular be effected in such a way that the electrostatic influence of a surface charge, which in Fig. 4 and Fig. 5 is schematically illustrated as layer 300, to which movable structure 3 is balanced.

[0030] Fig. Figure 5 shows an embodiment in which at least two voltage-sensitive electrodes 200a, 200b are provided on the housing component of the control and evaluation unit. The control and evaluation unit 20 is configured to vary the voltages V applied in pairs between each of the electrodes 200a, 200b and the movable structure 3 in order to compensate for the surface charge effect. This is particularly advantageous when the influence of the surface charges on the movable structure is not sufficiently homogeneous.

[0031] In particular, in the case of sensor arrangements 10 which, as in the Fig. 4 and Fig. 5, have movable structures 3 designed as asymmetric rockers, any existing surface charge can have a direct influence on the deflection of the torsion spring 4 or on the deflection of the movable structure 3 about the torsion axis 50 predetermined by the torsion spring 4. In the case of asymmetric rockers, due to the design and the additional mass 8, the area of ​​the movable structure 3 with the smaller, first mass 7a can, in particular, have a greater average distance from the housing component 21 or from the surface charge than the area of ​​the larger, second mass 7b. With such a design of the sensor arrangement 10, the electrostatic force caused by the surface charge thus acts more strongly on the side of the asymmetric rocker with the second mass 7b, even if the surface charge is homogeneously distributed in the layer 300.In general, the surface charge is characterized by stationary charges that follow a random distribution, so that an inhomogeneous surface charge density can typically be assumed, which effectively causes a torque on the movable structure 3 about the torsion axis 50.

[0032] In the embodiment of the Fig. 5, the two electrodes 200a, 200b are arranged in a lateral plane extending parallel to the main extension plane, on opposite sides of the torsion axis 72. The electrodes 200a, 200b can, in particular, be arranged symmetrically to the torsion axis 72 in order to detect an influence of the surface charges on the movable structure 3, which may be different in the regions of the first and second masses 7a, 7b.

[0033] In some embodiments, the movable structure 3 can typically also be subjected to a second voltage Vcm. By applying the second voltage Vcm to the electrode 200, the voltage applied between the electrode 200 and the movable structure 13 can also be specified and varied as V=Vcm - Vcap.

[0034] The deflection of the movable mass caused by the surface charge effect causes an offset, in particular a temperature-dependent offset, which is reflected in measurement signals detected by the sensor unit 30.

[0035] The influence of the surface charge on the movable structure 3 can be determined using the electrode 200. For this purpose, the voltage V applied between the movable structure 3 and the electrode 200 is varied, the deflection of the movable structure 3 is recorded as the measurement signal Aout of the sensor unit 30, and a peak of the measurement signal Aout is determined as a function of the voltage V. The peak of the measurement signal corresponds to a situation in which the surface charge effect is effectively compensated, so that the voltage value Vsc assigned to the peak represents a measure of the influence of the surface charges on the movable structure 3.

[0036] This can be illustrated as follows:

[0037] The force F caused by the surface charge effect, effectively acting on the moving structure 3 effectiveQsc is approximately: FeffectiveQsc∼ε⋅A⋅(V12d12−V22d22) with V1=Vsc+Vcap−Vcm=Vsc−V and V2=V'sc+Vcap−Vcm=V'sc−V

[0038] Here, V1 denotes the voltage applied between the first mass 7a of the movable structure 3 and the electrode 200, and V2 denotes the voltage applied between the second mass 7b of the movable structure 3 and the electrode 200. The influence V'sc, Vsc caused by the surface charge effect can vary; accordingly, the voltages V1 and V2 can be different. The distances d1 and d2 represent the distance to the layer 300 bearing the surface charges.

[0039] The force F acting on the movable structure 3 effectiveQsc can be approximately specified as: FeffectiveQsc∼ε⋅A⋅(Vsc−V)2d22−d12d12⋅d22

[0040] The position of the minimum or peak thus corresponds to an effective voltage Vsc caused by the surface charge effect. The same applies if multiple electrodes 200a, 200b are provided to determine the surface charge effect.

[0041] The force F acting on the movable structure 3 effectiveQsc can be detected as a measurement signal Aout of the sensor unit 30, in particular for calibrating the sensor arrangement 10 in the absence of an external physical stimulus, in order to determine the surface charge effect for each component individually by varying the applied voltage V, in particular after the sensor unit 30 has been bonded to the control and evaluation unit 20.

[0042] Fig. 6 illustrates by way of example the component-specific course of such a measurement signal as a function of the measurement signal Aout detected between the electrode 200 and the movable structure 3.

[0043] The quantitative determination of the surface charge effect enables, in particular, the compensation of the same within the framework of a control, regulation or digital correction of a sensor value which is generated by the control and evaluation unit 20 as a function of a detected deflection of the movable structure 3.

[0044] In the method according to the invention for operating the sensor arrangement 10, the at least one electrode 200 is subjected to a correction voltage Vsc, which compensates for the surface charge effect. This correction voltage Vsc corresponds to the effective voltage Vsc, which is determined, in particular, in the manner described above, based on the position of the peak of a measurement signal Aout acquired in the absence of an external physical stimulus. Such measurements can be performed as reference measurements during operation of the sensor arrangement 10 or at the factory before commissioning of the sensor arrangement 10.

[0045] For example, the voltage V applied between the electrode 200 and the movable structure 3 is predetermined by controlling the first voltage Vcap in such a way that the peak or the minimum of the Fig. 6, so that V = Vcm - Vcap = Vsc. The second voltage Vcm essentially specifies the potential level of the movable structure 3 during operation, which can itself vary, particularly during capacitive detection of the deflection of the movable structure 3. Preferably, the first voltage Vcap is controlled with respect to the second voltage Vcm during operation such that the voltage V applied between the electrode 200, 200a, 200b and the movable structure 3 is varied in the manner already described.

[0046] The correction voltage Vsc is determined in advance by varying the voltage V in the absence of an external physical stimulus. Such compensation, for example, in the context of a closed-loop or closed-loop control system, typically requires only a signal outside the actual usable bandwidth, so the usual application bandwidth is largely unaffected.

[0047] Fig. Figure 8 illustrates components for carrying out the method for operating the sensor arrangement 10 in a schematic block diagram. Fig. The arrangement shown in Figure 8 is equally suitable for determining the correction voltage Vsc by varying the voltage V applied between the electrode 200 and the movable structure 3.

[0048] To determine the surface charge effect, in a first method step, the deflection of the movable structure 3 is recorded by the sensor unit 30 while varying the voltage V in the absence of a physical stimulus. A readout module 23 of the control and evaluation unit 20 generates a measurement signal acc_out depending on the detected deflection. A control module 24 of the control and evaluation unit 20 determines the position of the peak or minimum of the measurement signal acc_out and thus the correction voltage Vsc. The correction voltage Vsc corresponds to an effective voltage Vsc caused by the surface charges.

[0049] For analog compensation of the surface charge effect, the electrode 200 is subjected to the correction voltage Vsc in a second process step. A digital-to-analog converter 25 is provided for this purpose.

[0050] The voltage applied to electrode 200 to compensate for the surface charge effect occurs regardless of whether an external physical stimulus acts on the movable structure 3. It is understood that in the presence of a physical stimulus, the measurement signal acc_out represents a sensor value representing this. For the acceleration sensors illustrated as examples in the drawings, this is accordingly an external acceleration or inertial force acting on the movable structure 3.

[0051] In the event of a change in the influence of the surface charge on the movable structure 3, particularly due to temperature, the correction voltage Vsc is determined again, for example in a further reference measurement during operation.

[0052] In an alternative embodiment, the dependence of the correction voltage Vsc on an operating temperature T is determined in advance, in particular for each component, in reference measurements. The correlations thus determined are stored, for example, digitally as mutually associated values ​​for the correction voltage Vsc and the operating temperature T in a memory module of the control and evaluation unit 30 and can be read out as needed, for example, when the operating temperature changes.

[0053] The correction voltage Vsc can also be determined once, for example, particularly during a trimming process, and integrated into a correlation-based digital temperature compensation. With such temperature compensation, the measurement situation of the sensor unit 30 is typically monitored with respect to the operating temperature T, and a temperature compensation parameter TCO is determined as a function of the operating temperature T.

[0054] To determine the temperature compensation parameter TCO for compensating for temperature influences on the sensor values ​​of the sensor arrangement 10, a temperature sensor unit for monitoring the operating temperature T is provided, for example. In such embodiments, the control and evaluation unit 20 is designed to determine a temperature compensation parameter TCO. For this purpose, the measurement situation of the sensor unit 30 is monitored to determine whether the current measurement situation corresponds to a reference measurement situation for which at least one reference measurement value of the sensor measurement variable is known. In parallel, the operating temperature T of the sensor unit 30 is monitored, in particular continuously.If the sensor unit 30 is in the reference measurement situation, a subsequent step checks whether the current operating temperature T of the sensor unit 30 is within a predetermined temperature range and requires a redetermination or updating of the temperature compensation parameter TCO. If this is the case, the current operating temperature value and the corresponding sensor value of the sensor unit 30 are recorded, and an updated temperature compensation parameter TCO is determined taking into account the known reference measurement value.

[0055] The measurement situation of the sensor unit 30 is determined by the sensor measurement variable. Thus, in the case of an acceleration sensor, the measurement situation is described by the magnitude of the acceleration acting on the sensor unit; in the case of a gyroscope, it is described by the magnitude of the rotational speed acting on the sensor unit. A reference measurement situation is defined here as a measurement situation for which the measurement variable to be recorded is known. For microelectromechanical sensor arrangements 10, a suitable reference measurement situation is generally one in which no external physical stimulus acts on the sensor unit 30.

[0056] For temperature-dependent compensation of the surface charge effect, the influence of the surface charge on the reference measurement value is determined in the reference measurement situation. This is done by determining the correction voltage Vsc or by varying the voltage V in the reference measurement situation in the manner already described. Fig. Figure 7 shows, by way of example, the dependence of the temperature compensation parameter TCO on the correction voltage Vsc. Values ​​of the temperature compensation parameter TCO thus determined represent correction values ​​for compensating a surface charge effect in a micromechanical sensor arrangement, wherein the correction value is determined based on a variation of the voltage V applied between the at least one electrode and the movable structure.

[0057] For temperature-dependent compensation of the surface charge effect, a first correction value DACC_T0 is preferably determined at a first temperature T0 and a second correction value DACC_T1 is determined at a second temperature T1. The determination of the second correction value can be carried out, in particular, by the user within the framework of a self-trimming routine in which the correction voltage Vsc and, consequently, the change in the sensor value are determined.

[0058] A surface charge-specific correction value TCOsc is given in a concrete embodiment, for example, by the relationship: TCOsc={[DACC_T0]−[DACC_T0]} / {T0−T1}, with [DACCT0]=[AccT0(V=Vsc)−AccT0(V=0)] and [DACCT1]=[AccT1(V=Vsc)−AccT1(Vx=0)]

[0059] Here, - T0 is the first operating temperature during a first determination of a sensor value of the sensor unit 30, which is carried out, for example, in the delivery state of the sensor arrangement 10; - T1 is the second operating temperature during a second determination of a sensor value, which is carried out, for example, by the user as part of the self-trimming routine; - DACCT0 is a deviation of the sensor value at the first operating temperature T0 caused by the surface charge effect; - DACCT1 a deviation of the sensor value caused by the surface charge effect at the second operating temperature T1 - AccT0(V=Vsc) is a sensor value determined at the first operating temperature T0, the voltage V applied between the electrode 200 and the movable structure 3 corresponding to the correction voltage Vsc; - AccT0(V=0) a sensor value determined at the first operating temperature T0, with no voltage (V=0) applied between the electrode 200 and the movable structure; - AccT1 (V=Vsc) a sensor value determined at the second operating temperature T1, wherein the voltage V applied between the electrode 200 and the movable structure 3 corresponds to the correction voltage Vsc; - AccT1 (V=0) a sensor value determined at the second operating temperature T1, with no voltage (V=0) applied between the electrode 200 and the movable structure.

[0060] For example, for a sensor arrangement 200, the following may apply: T0=27°C; T1=60°C, AccT0(V=Vsc)=5mg, AccT0(V=0)=60mg, AccT1(V=Vsc)=8mg; AccT1(V=0)=80mg

[0061] This results in a correction value TCOsc of 17 mg per 33°C, i.e. approximately 0.5 mg / K, where g is the acceleration due to gravity and K is the unit of temperature (here: Kelvin). QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 0 773 443 A1

[0002] DE 10 2019 217 333 A1

[0003] DE 10 2021 204 615 A1

[0003]

Claims

[1] Microelectromechanical sensor arrangement (10) comprising - a sensor unit (30) which is designed to detect an external physical stimulus via a deflection of a movable structure (3), wherein the movable structure (3) is arranged within a cavity (31) of the sensor unit (30); and - a control and evaluation unit (30) which is designed to determine a sensor value on the basis of the detected deflection of the movable structure (3), wherein the cavity (31) of the sensor unit (30) is delimited by a flat housing component of the control and evaluation unit (20), wherein the housing component (21) has an electrode (200, 200a, 200b) to which a voltage (V) can be applied, wherein the control and evaluation unit (20) is designed to vary a voltage (V) applied between the at least one electrode (200, 200a, 200b) and the movable structure (3) in order to compensate for a surface charge effect. [2] Sensor arrangement (10) according to claim 1, wherein the planar housing component (21) of the control and evaluation unit (20) is connected to a housing (32) of the sensor unit (30) by means of wafer bonding, in particular eutectic bonding. [3] Sensor arrangement (10) according to claim 1 or 2, wherein at least two electrodes (200, 200a, 200b) to which voltage can be applied are provided on the housing component (21) of the control and evaluation unit (20), and the control and evaluation unit (20) is designed to vary voltages (V) applied in pairs between one of the electrodes (200a, 200b) and the movable structure (3) in order to compensate for the surface charge effect. [4] Sensor arrangement (10) according to claim 3, wherein the movable structure (3) is designed as a deflectable, in particular asymmetric, rocker which is adjustably mounted about a torsion axis (72) running parallel to the main extension plane, wherein at least two of the electrodes (200, 200a, 200b) are arranged in a lateral plane parallel to the main extension plane on opposite sides of the torsion axis (72), in particular symmetrically to the torsion axis (72). [5] Method for operating a microelectromechanical sensor arrangement (1) according to one of the preceding claims, wherein a sensor value is determined on the basis of a detection of the deflection of the movable structure (3), wherein the at least one electrode (200, 200a, 200b) is subjected to a correction voltage (Vsc) compensating for the surface charge effect. [6] Method according to claim 5, wherein the correction voltage (Vsc) is determined on the basis of a detection of the deflection of the movable structure (3) in the absence of an external physical stimulus, wherein a voltage (V) applied between the at least one electrode (200, 200a, 200b) and the movable structure (3) is varied. [7] Method according to claim 6, wherein the voltage (V) corresponding to a peak of the detected deflection is determined as the correction voltage (Vsc). [8] Method for determining a correction value (TCO, TCOsc, DACCT0, DACCT1) for compensating a surface charge effect in a micromechanical sensor arrangement (10) according to one of the preceding claims 1 to 5, wherein the correction value (TCO, TCOsc, DACC_T0, DACCTSelftrim) is determined on the basis of a detection of the deflection of the movable structure (3) in the absence of an external physical stimulus, wherein a voltage (V) applied between the at least one electrode (200, 200a, 200b) and the movable structure (3) is varied. [9] Method according to claim 8, wherein the voltage (V) corresponding to a peak of the detected deflection is determined when determining the correction value (TCO, TCOsc, DACCT0, DACCT1). [10] Method according to claim 8 or 9, wherein for temperature-dependent compensation of the surface charge effect, a first correction value (DACCT0) is determined at a first operating temperature (T0) and a second correction value (DACCT1) is determined at a second operating temperature (T1).

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