Micromechanical component for a pressure sensor device

Abstract

Micromechanical component for a pressure sensor device with: a housing (10) hermetically enclosing an inner volume (14) with a membrane (16) which separates a reference pressure (pr) present in the inner volume (14) from an external pressure (p) present in an outer volume (18) of the housing (10); a rocker structure (22) tiltable about a rotational axis (20) with at least one first actuator electrode (24a) formed on the rocker structure (22) on a first side of the rotational axis (20) and at least one second actuator electrode (24b) formed on the rocker structure (22) on a second side of the rotational axis (20), wherein the rocker structure (22) is connected to the membrane (16) in such a way that, when the pressure is equal between the external pressure (p) and the reference pressure (pr), the rocker structure (22) and its actuator electrodes (24a, 24b) are in their initial positions, and when the pressure is different between the external pressure (p) and the reference pressure (pr), the rocker structure (22) is rotated from its initial position about the rotational axis (20); and at least one first stator electrode (28a) fixedly arranged on the housing (10) and associated with the at least one first actuator electrode (24a) and at least one second stator electrode (28b) fixedly arranged on the housing (10) and associated with the at least one second actuator electrode (24b); when the rocker structure (22) and its actuator electrodes (24a, 24b) are in their initial positions, a first capacitance between the at least one first actuator electrode (24a) and the at least one first stator electrode (28a) differs from a second capacitance between the at least one second actuator electrode (24b) and the at least one second stator electrode (28b), characterized in that a first surface area of the first electrode surface (A1) of the at least one first stator electrode (28a) is equal to a second surface area of the second electrode surface (A2) of the at least one second stator electrode (28b); a first sensitivity (S1) of a first capacitor comprising the at least one first actuator electrode (24a) and the at least one first stator electrode (28a) is equal to a second sensitivity (S2) of a second capacitor comprising the at least one second actuator electrode (24b) and the at least one second stator electrode (28b); a first mean basic distance (G1) of the at least one first stator electrode (28a) to the at least one first actuator electrode (24a) in its initial position deviates from a second mean basic distance (G2) of the at least one second stator electrode (28b) to the at least one second actuator electrode (24b) in its initial position; and the micromechanical component is designed to measure a pressure deviation of the external pressure (p) from a working pressure (pw), wherein at the working pressure (pw) a first mean distance (d1 (pw)) of the at least one first stator electrode (28a) to the at least one first actuator electrode (24a) is equal to a second mean distance (d2 (pw)) of the at least one second stator electrode (28b) to the at least one second actuator electrode (24b), by forming a difference between the first mean basic distance (G1) and the second mean basic distance (G2) such that: G 1 − G 2 = 2 ∗ Δ d 1 (pw), where Δd1(pw) is a first mean deflection of the at least one first actuator electrode 24a from its initial position at the external pressure p equal to the working pressure pw, G1 is the first mean basic distance of the at least one first stator electrode (28a) to the at least one first actuator electrode (24a) in its initial position, and G2 is the second mean basic distance of the at least one second stator electrode (28b) to the at least one second actuator electrode (24b) in its initial position.

Description

[0001] The invention relates to a micromechanical component for a pressure sensor device and a pressure sensor device. The invention also relates to a method for producing a micromechanical component for a pressure sensor device. Furthermore, the invention relates to the use of a micromechanical component for measuring a pressure deviation from a working pressure. State of the art

[0002] US 2014 / 0060169 A1 describes a pressure sensor with a rocker structure that can be tilted about a rotational axis. The rocker structure has a first actuator electrode on a first side of the rotational axis and a second actuator electrode on a second side of the rotational axis. Furthermore, the rocker structure is enclosed in an airtight housing, with a membrane arranged on the housing separating a reference pressure present in the housing from an external pressure / measurement pressure present in an external volume of the housing. The housing also has a first stator electrode associated with the first actuator electrode and a second stator electrode associated with the second actuator electrode.

[0003] Further prior art is disclosed in the published patent applications US 2013 / 0 234 263 A1, US 2013 / 0 047 726 A1 and US 2013 / 0 319 117 A1. Disclosure of the invention

[0004] The invention provides a micromechanical component having the features of claim 1, a pressure sensor device having the features of claim 2, a use of a micromechanical component for measuring a pressure deviation having the features of claim 3 and a method for producing a micromechanical component for a pressure sensor device having the features of claim 4. Advantages of the invention

[0005] The present invention provides possibilities for determining a pressure change based on an easily recognizable capacitance change / total capacitance change, which is (at least approximately) linear to the pressure change. The present invention thus facilitates the determination of the pressure change by evaluating the (at least approximately) linear capacitance change / total capacitance change and enables the use of cost-effective and space-saving evaluation electronics for this process. The present invention thus contributes to reducing and minimizing the manufacturing costs of pressure sensor devices.

[0006] Furthermore, the present invention allows a pressure change to be detected / detected with comparatively high accuracy and a relatively low error rate, despite the use of simple and space-saving evaluation electronics. In addition, the present invention contributes to the realization of pressure sensor devices that can be easily calibrated and are relatively insensitive to external stress.

[0007] According to the invention, the micromechanical component is designed to measure a pressure deviation of the external pressure from a working pressure pw, in which: A1∗S1A2∗S2=(G1−S1∗pw)3(G2+S2∗pw)3 where A1 is the first electrode area of the at least one first stator electrode, A2 is the second electrode area of the at least one second stator electrode, G1 is the first average basic distance between the at least one first stator electrode and the at least one first actuator electrode in its initial position, G2 is the second average basic distance between the at least one second stator electrode and the at least one second actuator electrode in its initial position, S1 is a first sensitivity of a first capacitor made up of the at least one first actuator electrode and the at least one first stator electrode, and S2 is a second sensitivity of a second capacitor made up of the at least one second actuator electrode and the at least one second stator electrode. As explained in more detail below, this brings about the advantageous linearity of the capacitance change / total capacitance change to the pressure change.

[0008] According to the invention, the first electrode area of the at least one first stator electrode is equal to the second electrode area of the at least one second stator electrode, the first sensitivity is equal to the second sensitivity, and a difference between the first mean basic distance and the second mean basic distance is designed such that, at the working pressure, a first mean distance of the at least one first stator electrode to the at least one first actuator electrode is equal to a second mean distance of the at least one second stator electrode to the at least one second actuator electrode.

[0009] The above-mentioned advantages are also guaranteed in a pressure sensor device with such a micromechanical component.

[0010] The use of a corresponding micromechanical component for measuring a pressure deviation of the external pressure from the working pressure also creates the described advantages.

[0011] Furthermore, implementing a corresponding method for producing a micromechanical component for a pressure sensor device also achieves the described advantages. The method can be further developed according to the embodiments of the micromechanical component described above. Short description of the drawings

[0012] Further features and advantages of the present invention are explained below with reference to the figures. They show: Fig. 1a and Fig. 1b schematic representations of an embodiment of the micromechanical component according to the invention; Fig. 2 a schematic representation of another micromechanical component; Fig. 3 a schematic representation of yet another micromechanical component; and Fig. 4 a flowchart for explaining an embodiment of the method for producing a micromechanical component for a pressure sensor device. Embodiments of the invention

[0013] The micromechanical components described below are particularly advantageous for use in a pressure sensor device. However, it should be noted that the usability of the micromechanical components is not limited to this intended use.

[0014] Fig. 1a and Fig. 1b show schematic representations of an embodiment of the micromechanical component according to the invention.

[0015] The Fig. 1a and Fig. The micromechanical component shown schematically in Fig. 1b has a housing 10, of which, however, for the sake of clarity, only a carrier plate / substrate 12 is shown in the Fig. 1a and Fig. 1b. The housing 10 hermetically encloses an internal volume 14, wherein a membrane 16 of the housing 10 delimits a reference pressure pr present in the internal volume 14 from an external pressure p present in an external volume 18. The membrane 16 can, for example, hermetically seal an opening structured by the carrier plate 12. The reference pressure pr present in the internal volume 14 is preferably (virtually) equal to zero. In particular, a vacuum can be present in the internal volume 14.

[0016] The micromechanical component also comprises a rocker structure 22 that can be tilted / rotated about a rotation axis 20 and is preferably arranged in the internal volume 14. The rocker structure 22 is formed with at least one first actuator electrode 24a located on a first side of the rotation axis 20 and with at least one second actuator electrode 24b located on a second side of the rotation axis 20. Furthermore, the rocker structure 22 is connected to the membrane 16 in such a way that when the external pressure p and the reference pressure pr are equal, the rocker structure 22 and its actuator electrodes 24a and 24b are in their initial positions.

[0017] Fig. 1a shows the rocker structure 22 at an external pressure p (approximately) equal to the reference pressure pr. In contrast, the Fig. 1b shows a situation in which the external pressure p present in the external volume 18 is equal to a working pressure pw (which differs from the reference pressure pr). It can be seen that this pressure inequality between the external pressure p and the reference pressure pr results in a pressure force 26, which bulges or inwards the membrane 16 and leads to Fig. 1b the rocker structure 22 from the (in Fig. 1a) is rotated around the axis of rotation 20.

[0018] The working pressure pw can be understood as an external pressure p, which is usually present in an application area of the micromechanical component. The micromechanical component of the Fig. 1a and Fig. 1b is particularly “designed” for the working pressure pw, ie the micromechanical component is designed to measure a deviation of the external pressure p from the working pressure pw, or a difference between the external pressure p and the working pressure pw.

[0019] The micromechanical component also has at least one first stator electrode 28a fixedly arranged on the housing 10 and associated with the at least one first actuator electrode 24a. Correspondingly, at least one second stator electrode 28b associated with the at least one second actuator electrode 24b is also fixedly arranged on the housing 10. A fixed arrangement of the stator electrodes 28a and 28b on the housing 10 is understood to mean that a position / position of the stator electrodes 28a and 28b (in contrast to a position / position of the actuator electrodes 24a and 24b) is not affected by a tilting movement of the rocker structure 22 about the rotation axis 20. In the example of the Fig. 1a and Fig. 1b, the stator electrodes 28a and 28b are attached to a surface of the support plate 12 that defines the internal volume 14, wherein the stator electrodes 28a and 28b are optionally insulated from the support plate 12 by means of at least one insulating layer 30. As an alternative or in addition, (further) stator electrodes can also be attached to the housing 10 on a side of the rocker structure 22 facing away from the support plate 12 and / or the membrane 16.

[0020] A pressure sensor device equipped with the rocker structure 22 is often also referred to as a differentially operating pressure sensor, which measures an external pressure p by means of the warping of the membrane 16 and the resulting tilting / rotation of the rocker structure 22 about the rotation axis 20 by measuring a total capacitance change ΔC of a sum of a first capacitance C1 of a first capacitor from the at least one first actuator electrode 24a and the at least one first stator electrode 28a and a second capacitance C2 of a second capacitor from the at least one second actuator electrode 24b and the at least one second stator electrode 28b. The first capacitance C1 is defined according to equation (Eq. 1) with: C1~A1d1(p) , where A1 is a first electrode area (first total electrode area) of the at least one first stator electrode 28a and d1(p) is a first average distance (dependent on the external pressure p) of the at least one first stator electrode 28a to the at least one first actuator electrode 24a.

[0021] (The first electrode area / total electrode area A1 is an area / total area of at least one surface of the at least one first stator electrode 28a aligned with the rocker structure 22.)

[0022] Accordingly, the second capacitance C2 is defined according to equation (Eq.2) with: C2~A2d2(p) , where A2 is a second electrode area (second total electrode area) of the at least one second stator electrode 28b, and d2(p) is a second average distance (dependent on the external pressure p) between the at least one second stator electrode 28b and the at least one second actuator electrode 24b. (The second electrode area / total electrode area A2 indicates a surface area / total surface area of at least one surface of the at least one second stator electrode 28b aligned with the rocker structure 22.)

[0023] When the pressure between the external pressure p and the reference pressure pr is equal, the actuator electrodes 24a and 24b are in their initial positions, where Fig. 1a indicates a first average basic distance G1 (=d1 (p=pr)) of the at least one first stator electrode 28a to the at least one first actuator electrode 24a in its initial position, and a second average basic distance G2 (=d2(p=pr)) of the at least one second stator electrode 28b to the at least one second actuator electrode 24b in its initial position. In the event of a pressure difference between the external pressure p and the reference pressure pr, the at least one first actuator electrode 24a exhibits a first average deflection Δd1(p) from its initial position, and the at least one second actuator electrode 24b exhibits a second average deflection Δd2(p) from its initial position. The first average distance d1(p) and the second average distance d2(p) can thus be written according to equations (Eq. 3) and (Eq. 4): d1(p)=G1−Δd1(p) d2(p)=G2+Δd2(p)

[0024] For the first capacitor (from the at least one first actuator electrode 24a and the at least one first stator electrode 28a), a first sensitivity S1 is defined according to equation (Eq. 5) with: S1=Δd1(p)p

[0025] Accordingly, for a second sensitivity S2 of the second capacitor (from the at least one second actuator electrode 24b and the at least one second stator electrode 28b), equation (Eq. 6) applies with: S2=Δd2(p)p

[0026] The total capacity change ΔC is given according to equation (Eq. 7) with: ΔC=C1+C2~A1G1−S1∗p−A2G2+S2∗p

[0027] A Taylor expansion for the total capacity change ΔC at the working pressure pw results from equation (Eq. 8) with: TΔC(p;pw)~ΔC(pw)+∂ΔC(pw)∂p∗(p−pw)+12∗∂2ΔC(pw)∂p2(p−pw)2+⋯

[0028] The first non-linearity-causing term in the Taylor expansion is proportional to ∂2ΔC(pw)∂p2. This term ∂2ΔC(pw)∂p2 is given in equation (Eq. 9): ∂2ΔC(pw)∂p2~2∗S1∗A1(G1−S1∗pw)3−2∗S2∗A2(G2+S2∗pw)3 ∂2ΔC(pw)∂p2 is equal to zero if the condition of equation (Eq. 10) is fulfilled with: A1∗S1A2∗S2=(G1−S1∗pw)3(G2+S2∗pw)3

[0029] Equation (Eq. 10) can also be transformed to equation (Eq. 11) with: A1∗S1A2∗S2=(G1−Δd1(pw))3(G2+Δd2∗(pw))3 where Δd1(pw) is a first mean deflection of the at least one first actuator electrode 24a from its initial position at the external pressure p equal to the working pressure pw and Δd2(pw) is a second mean deflection of the at least one second actuator electrode 24b from its initial position at the external pressure p equal to the working pressure pw.

[0030] If the condition of equation (Eq. 10) and / or equation (Eq. 11) applies, the total capacity change ΔC reacts (as can be seen from the Taylor expansion) (almost) linearly to a pressure deviation of the external pressure p from the working pressure pw. Equation (Eq. 8) then simplifies to equation (Eq. 12) with: TΔC(p;pw)∼ΔC(pw)+∂ΔC(pw)∂p∗(p−pw)+0+⋯

[0031] If the condition of equation (Eq. 10) and / or equation (Eq. 11) is met, the determined total capacitance change ΔC (or a corresponding signal) can be converted into a linear output signal when measuring a pressure deviation of the external pressure p from the working pressure pw (or the current external pressure p). Therefore, if the condition of equation (Eq. 10) and / or equation (Eq. 11) is met, a comparatively simple and inexpensive evaluation circuit can be used to measure the pressure deviation of the external pressure p from the working pressure pw (or the current external pressure p). Furthermore, despite the use of the comparatively simple and inexpensive evaluation circuit, the pressure deviation of the external pressure p from the working pressure pw (or the current external pressure p) can be measured with comparatively high accuracy and a relatively low error rate if the condition of equation (Eq. 10) and / or equation (Eq. 11) is met.

[0032] Any micromechanical component that satisfies the condition of equation (Eq. 10) and / or equation (Eq. 11) is thus advantageously designed to measure the pressure deviation of the external pressure p from the working pressure pw (or the current external pressure p). Furthermore, any micromechanical component that satisfies the condition of equation (Eq. 10) and / or equation (Eq. 11) can be calibrated (due to the linearity between the total capacitance change ΔC and the pressure deviation of the external pressure p from the working pressure pw) solely by measuring two different pressure values. The amount of work required for calibrating is thus comparatively low for the micromechanical component that satisfies the condition of equation (Eq. 10) and / or equation (Eq. 11).

[0033] The micromechanical component of the Fig. 1a and Fig. 1b satisfies the conditions of equations (Eq. 10) and (Eq. 11). For example, the first electrode area A1 (first total electrode area) of the at least one first stator electrode 28a is equal to the second electrode area A2 (second total electrode area) of the at least one second stator electrode 28b. Furthermore, the first sensitivity S1 of the first capacitor is equal to the second sensitivity S2 of the second capacitor, which is why the first mean deflection Δd1(pw) (of the at least one first actuator electrode 24a from its initial position at the external pressure p equal to the working pressure pw) is equal to the second mean deflection Δd2(pw) (of the at least one second actuator electrode 24b from its initial position at the external pressure p equal to the working pressure pw).

[0034] Equation (Eq. 10) and equation (Eq. 11) simplify (with A1 = A2 and S1 = S2) to equation (Eq. 13) and equation (Eq. 14) respectively with: G1−G2=2∗S1∗pw G1−G2=2∗Δd1(pw)

[0035] The mean basic distances G1 and G2 are deliberately chosen to be so different that their difference corresponds to twice the first mean deflection Δd1(pw) (of the at least one first actuator electrode 24a from its initial position at the external pressure p equal to the working pressure pw).

[0036] From equations (Eq. 3) and (Eq. 4) the equations (Eq. 15) and (Eq. 16) can be derived (with A1 = A2 and S1 = S2) with: d1(pw)=G2+2∗Δd1(pw)−Δd1(pw)=G2+Δd1(pw) d2(pw)=G2+Δd2(p)=G2+Δd1(p)

[0037] The mean basic distances G1 and G2 are thus set unequally such that at the working pressure pw the first mean distance d1(pw) (of the at least one first stator electrode 28a to the at least one first actuator electrode 24a) is equal to the second mean distance d2(pw) (of the at least one second stator electrode 28b to the at least one second actuator electrode 24b).

[0038] The micromechanical component of the Fig. 1a and Fig. The pressure sensor device implemented in Figure 1b also reacts relatively insensitively to external pressure or force exerted on the housing 10. If, for example, the carrier plate 12 is bent, the bending generally leads to a first bending-related change in distance between the at least one first actuator electrode 24a and the at least one first stator electrode 28a, which is (almost) equal to a second bending-related change in distance between the at least one second actuator electrode 24b and the at least one second stator electrode 28b. The effects of the bending-related changes in distance thus compensate for each other and therefore generally hardly lead to an error signal.

[0039] Fig. 2 shows a schematic representation of another micromechanical component.

[0040] The micromechanical component of the Fig. 2 fulfills the advantages of the previously described embodiment, although the first average basic distance G1 (of the at least one first stator electrode 28a to the at least one first actuator electrode 24a in its initial position) is equal to the second average basic distance G2 (of the at least one second stator electrode 28b to the at least one second actuator electrode 24b in its initial position). However, the first electrode area A1 (first total electrode area) of the at least one first stator electrode 28a and the second electrode area A2 (second total electrode area) of the at least one second stator electrode 28b are set so differently that the conditions of equations (Eq. 10) and (Eq. 11) are met.

[0041] The first sensitivity S1 (of the first capacitor comprising the at least one first actuator electrode 24a and the at least one first stator electrode 28a) can be equal to the second sensitivity S2 (of the second capacitor comprising the at least one second actuator electrode 24b and the at least one second stator electrode 28b). Equations (Eq. 10) and (Eq. 11) simplify (with G1 = G2 and S1 = S2) to equations (Eq. 17) and (Eq. 18) with: A1A2=(G1−S1∗pw)3(G1+S1∗pw)3 A1A2=(G1−Δd1(pw))3(G1+Δd1(pw))3

[0042] Alternatively, in addition to the electrode areas A1 and A2, the sensitivities S1 and S2 can also be set differently. In particular, by setting the sensitivities S1 and S2 differently, a difference between the first capacitance C1 and the second capacitance C2 can be kept low. This can be ensured by reducing the second sensitivity S2 (compared to the first sensitivity S1) when the second electrode area A2 is larger (relative to the first electrode area A1), and by reducing the first sensitivity S1 (compared to the second sensitivity S2) when the first electrode area A1 is larger (relative to the second electrode area A2).

[0043] In the Fig. 2, the at least one first stator electrode 28a has a larger first electrode area A1 (relative to the second electrode area A2), but is arranged at a first mean rotational axis distance t1 from the rotational axis 20 (or a projection of the rotational axis 20 onto a surface of the carrier plate 12 equipped with the stator electrodes 28a and 28b), which is greater than a second mean rotational axis distance t2 of the at least one second stator electrode 28b from the rotational axis 20 (or the projection of the rotational axis 20 onto the surface equipped with the stator electrodes 28a and 28b). The first sensitivity S1 is thus reduced (compared to the second sensitivity S2). Due to this advantageous ratio between the sensitivities S1 and S2, a difference between the first capacitance C1 and the second capacitance C2 remains (despite the unequal electrode areas A1 and A2) during operation of the micromechanical component of the Fig. 2 comparatively low. For the micromechanical component of the Fig. 2, evaluation circuits can therefore also be used which are designed for only relatively small differences between the first capacitance C1 and the second capacitance C2.

[0044] The micromechanical component of the Fig. 2 also exhibits a relatively low stress sensitivity (while maintaining the linearity between the total capacitance change ΔC and the pressure deviation of the external pressure p from the working pressure pw). If the support surface 12 is bent, for example, a first partial capacitance change of the first capacitance C1 due to the first bending-related distance change (between the at least one first actuator electrode 24a and the at least one first stator electrode 28a) can be compensated by a second partial capacitance change of the second capacitance C2 due to the second bending-related distance change (between the at least one second actuator electrode 24b and the at least one second stator electrode 28b).

[0045] Fig. 3 shows a schematic representation of yet another micromechanical component.

[0046] The micromechanical component of the Fig. 3 fulfills the condition of equation (Eq. 10) and / or equation (Eq. 11) and thus creates the advantages described above.

[0047] This is ensured by setting the sensitivities S1 and S2 differently for the same basic distances G1 and G2 and the same electrode areas / total electrode areas A1 and A2 so that the conditions given above in equations (Eq. 10) and (Eq. 11) are met. Fig. 3, the mean rotational axis distances t1 and t2 are also the same. However, the at least one first stator electrode 28a has (at least partially) an additional insulating covering 32 compared to the at least one second stator electrode 28b. Preferably, the additional insulating covering 32 is present on the at least one surface of the at least one first stator electrode 28a that is aligned with the rocker structure 22. The additional insulating covering 32 can also be described as a dielectric present locally only on the at least one first stator electrode 28a. (In an alternative embodiment, the at least one second stator electrode 28b can have an additional insulating covering 32 corresponding to the at least one first stator electrode 28a.)

[0048] Equations (Eq. 10) and (Eq. 11) simplify (with G1 = G2 and A1 = A2) to equations (Eq. 19) and (Eq. 20) with: S1S2=(G1−S1∗pw)3(G1+S2∗pw)3 S1S2=(G1−Δd1(pw))3(G1+Δd2∗(pw))3 (Δd2(pw) can also be equal to Δd1(pw).)

[0049] Combinations of features are also possible for all of the micromechanical components mentioned above. It should also be noted that the pressure sensors realized using the micromechanical components can be manufactured and integrated as modules with acceleration and yaw rate sensors.

[0050] Fig. 4 shows a flowchart for explaining an embodiment of the method for producing a micromechanical component for a pressure sensor device.

[0051] The method described below can be implemented, for example, to manufacture one of the micromechanical components explained above. However, it should be noted that the feasibility of the method described below is not limited to the manufacture of one of these micromechanical components.

[0052] In a method step St1, a rocker structure is formed which can be tilted about a later axis of rotation during operation of the micromechanical component, wherein at least one first actuator electrode is formed on a first side of the later axis of rotation and at least one second actuator electrode is formed on the rocker structure on a second side of the later axis of rotation. In a method step St2, a housing is formed which encloses an internal volume in an airtight manner. The housing is formed with at least one first stator electrode which is fixedly arranged on the housing and assigned to the at least one first actuator electrode, and at least one second stator electrode which is fixedly arranged on the housing and assigned to the at least one second actuator electrode.In addition, a reference pressure present in the internal volume is separated from an external pressure present in an external volume of the housing by means of a membrane, and the rocker structure is connected to the membrane in such a way that during operation of the micromechanical component, when the external pressure and the reference pressure are equal, the rocker structure and its actuator electrodes are in their initial positions and when the external pressure and the reference pressure are different, the rocker structure is rotated from its initial position about the axis of rotation.

[0053] The at least one first stator electrode is formed with a first electrode area that is larger or smaller than a second electrode area of the at least one second stator electrode, with a different first average basic distance from the at least one first actuator electrode in its initial position than a different second average basic distance from the at least one second stator electrode to the at least one second actuator electrode in its initial position, and / or with an additional insulating covering compared to the at least one second stator electrode. Thus, the method described here also provides the advantages already listed above.

[0054] For example, the micromechanical component is designed to measure a pressure deviation of the external pressure from a working pressure pw by specifying that the above-mentioned condition of equations (Eq. 10) and (Eq. 11) is met. In particular, the first electrode area can be set equal to the second electrode area and the first sensitivity can be set equal to the second sensitivity. In this case, a difference between the first average basic distance and the second average basic distance is preferably formed such that, at the working pressure, a first average distance of the at least one first stator electrode to the at least one first actuator electrode is equal to a second average distance of the at least one second stator electrode to the at least one second actuator electrode.

[0055] To achieve the advantageous difference between the first mean base spacing and the second mean base spacing, the single first stator electrode or at least one of the first stator electrodes and the single second stator electrode or at least one of the second stator electrodes can first be formed on at least a portion of the housing. Preferably, a first sacrificial layer is then deposited on all stator electrodes formed on the portion of the housing (before the actual sacrificial layer deposition), and the first sacrificial layer is removed either on the single first stator electrode or the at least one of the first stator electrodes, or on the single second stator electrode or the at least one of the second stator electrodes.Only then (as the actual sacrificial layer deposition) are a second sacrificial layer and at least one material of the future actuator electrodes deposited on all stator electrodes formed on the part of the housing. Even a simple deposition process for forming the first sacrificial layer allows for a very precise determination of the layer thickness of the first sacrificial layer and thus the difference between the first mean base spacing and the second mean base spacing. Using the process described here, it is thus possible to set a very precisely defined and easily repeatable distance difference between the two base spacings.

[0056] Alternatively, a (single) sacrificial layer can be deposited on all stator electrodes formed on the part of the housing, and the sacrificial layer can be thinned back either on the single first stator electrode or on the at least one of the first stator electrodes, or on the single second stator electrode or on the at least one of the second stator electrodes, before the at least one material of the future actuator electrodes is deposited on all stator electrodes formed on the part of the housing. This process is less labor-intensive.

[0057] The processes described here can also be combined with one another. Baseline distances to stator electrodes, which are located on a side of the rocker structure remote from the membrane, can also be advantageously determined using the procedure described here. The previously described processes can also be applied multiple times to create a stepped shape for at least one of the baseline distances. The goal here is, again, to achieve the most uniform average distances possible at the working pressure.

Claims

[1] Micromechanical component for a pressure sensor device with: a housing (10) hermetically enclosing an inner volume (14) with a membrane (16) which separates a reference pressure (pr) present in the inner volume (14) from an external pressure (p) present in an outer volume (18) of the housing (10); a rocker structure (22) tiltable about a rotational axis (20) with at least one first actuator electrode (24a) formed on the rocker structure (22) on a first side of the rotational axis (20) and at least one second actuator electrode (24b) formed on the rocker structure (22) on a second side of the rotational axis (20), wherein the rocker structure (22) is connected to the membrane (16) in such a way that, when the pressure is equal between the external pressure (p) and the reference pressure (pr), the rocker structure (22) and its actuator electrodes (24a, 24b) are in their initial positions, and when the pressure is different between the external pressure (p) and the reference pressure (pr), the rocker structure (22) is rotated from its initial position about the rotational axis (20); and at least one first stator electrode (28a) fixedly arranged on the housing (10) and associated with the at least one first actuator electrode (24a) and at least one second stator electrode (28b) fixedly arranged on the housing (10) and associated with the at least one second actuator electrode (24b); when the rocker structure (22) and its actuator electrodes (24a, 24b) are in their initial positions, a first capacitance between the at least one first actuator electrode (24a) and the at least one first stator electrode (28a) differs from a second capacitance between the at least one second actuator electrode (24b) and the at least one second stator electrode (28b), characterized by , that a first surface area of the first electrode surface (A1) of the at least one first stator electrode (28a) is equal to a second surface area of the second electrode surface (A2) of the at least one second stator electrode (28b); a first sensitivity (S1) of a first capacitor comprising the at least one first actuator electrode (24a) and the at least one first stator electrode (28a) is equal to a second sensitivity (S2) of a second capacitor comprising the at least one second actuator electrode (24b) and the at least one second stator electrode (28b); a first mean basic distance (G1) of the at least one first stator electrode (28a) to the at least one first actuator electrode (24a) in its initial position deviates from a second mean basic distance (G2) of the at least one second stator electrode (28b) to the at least one second actuator electrode (24b) in its initial position; and the micromechanical component is designed to measure a pressure deviation of the external pressure (p) from a working pressure (pw), wherein at the working pressure (pw) a first mean distance (d1 (pw)) of the at least one first stator electrode (28a) to the at least one first actuator electrode (24a) is equal to a second mean distance (d2 (pw)) of the at least one second stator electrode (28b) to the at least one second actuator electrode (24b), by forming a difference between the first mean basic distance (G1) and the second mean basic distance (G2) such that: G1−G2=2∗Δd1(pw), where Δd1(pw) is a first mean deflection of the at least one first actuator electrode 24a from its initial position at the external pressure p equal to the working pressure pw, G1 is the first mean basic distance of the at least one first stator electrode (28a) to the at least one first actuator electrode (24a) in its initial position, and G2 is the second mean basic distance of the at least one second stator electrode (28b) to the at least one second actuator electrode (24b) in its initial position. [2] Pressure sensor device with a micromechanical component according to claim 1. [3] Use of a micromechanical component according to claim 1 for measuring a pressure deviation of the external pressure (p) from the working pressure (pw). [4] Method for producing a micromechanical component for a pressure sensor device, comprising the steps: Forming a rocker structure (22) which can be tilted about a later axis of rotation (20) during operation of the micromechanical component, wherein at least one first actuator electrode (24a) is formed on a first side of the later axis of rotation (20) and at least one second actuator electrode (24b) is formed on the rocker structure (22) on a second side of the later axis of rotation (20) (St1); and Forming a housing (10) that hermetically encloses an internal volume (14) with at least one first stator electrode (28a) that is fixedly arranged on the housing (10) and associated with the at least one first actuator electrode (24a), and at least one second stator electrode (28b) that is fixedly arranged on the housing (10) and associated with the at least one second actuator electrode (24b), wherein a reference pressure (pr) present in the internal volume (14) is delimited by means of a membrane (16) from an external pressure (p) present in an external volume (18) of the housing (10), and the rocker structure (22) is connected to the membrane (16) in such a way that, during operation of the micromechanical component, when the external pressure (p) and the reference pressure (pr) are equal, the rocker structure (22) and its actuator electrodes (24a,24b) are in their initial positions and, in the event of a pressure imbalance between the external pressure (p) and the reference pressure (pr), the rocker structure (22) is rotated from its initial position about the rotation axis (20) (St2);, wherein it is determined that when the rocker structure (22) and its actuator electrodes (24a, 24b) are in their initial positions, a first capacitance between the at least one first actuator electrode (24a) and the at least one first stator electrode (28a) differs from a second capacitance between the at least one second actuator electrode (24b) and the at least one second stator electrode (28b), characterized by the steps: Forming a first surface area of the first electrode surface (A1) of the at least one first stator electrode (28a) equal to a second surface area of the second electrode surface (A2) of the at least one second stator electrode (28b); Forming a first sensitivity (S1) of a first capacitor from the at least one first actuator electrode (24a) and the at least one first stator electrode (28a) equal to a second sensitivity (S2) of a second capacitor from the at least one second actuator electrode (24b) and the at least one second stator electrode (28b); Forming a first average basic distance (G1) of the at least one first stator electrode (28a) to the at least one first actuator electrode (24a) in its initial position, deviating from a second average basic distance (G2) of the at least one second stator electrode (28b) to the at least one second actuator electrode (24b) in its initial position; and Designing the micromechanical component for measuring a pressure deviation of the external pressure (p) from a working pressure (pw), wherein at the working pressure (pw) a first mean distance (d1 (pw)) of the at least one first stator electrode (28a) to the at least one first actuator electrode (24a) is equal to a second mean distance (d2 (pw)) of the at least one second stator electrode (28b) to the at least one second actuator electrode (24b), by forming a difference between the first mean basic distance (G1) and the second mean basic distance (G2) such that: G1−G2=2*Δd1(pw), where Δd1 (pw) is a first mean deflection of the at least one first actuator electrode 24a from its initial position at the external pressure p equal to the working pressure pw, G1 is the first mean basic distance of the at least one first stator electrode (28a) to the at least one first actuator electrode (24a) in its initial position, and G2 is the second mean basic distance of the at least one second stator electrode (28b) to the at least one second actuator electrode (24b) in its initial position.

Images