MEMS Component And Method For Operating A MEMS Component

Abstract

The invention relates to an MEMS assembly comprising a diaphragm and a fixed first pair of electrodes, the first pair of electrodes being configured to generate a first electrostatic force on the diaphragm when a first voltage is applied between the diaphragm and the first pair of electrodes, in order to reduce a restoring force of the diaphragm generated when the diaphragm deflects in the direction of the first pair of electrodes. The invention also relates to a method for operating the MEMS assembly.

Description

Technical Field

[0001] The present invention relates to a MEMS component, particularly a MEMS microphone or MEMS pressure sensor, particularly a MEMS relative pressure sensor, and to a method for operating a MEMS component. Background Technology

[0002] Patent document KR 10-1496817 B1 discloses a MEMS transducer.

[0003] The publicly available document CN 107872760 A discloses a MEMS transducer.

[0004] Publication DE 10 2014 212 340 A1 discloses a microphone. Summary of the Invention

[0005] The objective of this invention is to provide a MEMS component.

[0006] The objective of this invention is to provide a method for operating MEMS components.

[0007] The task is solved by means of the corresponding subject matter of the independent claim. Advantageous embodiments of the invention are the subject matter of the various dependent claims.

[0008] According to the first aspect, a MEMS component, particularly a MEMS microphone or MEMS pressure sensor, especially a MEMS relative pressure sensor, is proposed, having: diaphragms and The first pair of electrodes is fixed. The first pair of electrodes is configured to generate a first electrostatic force on the diaphragm when a first voltage is applied between the diaphragm and the first pair of electrodes, so as to reduce the restoring force generated when the diaphragm deflects toward the first pair of electrodes.

[0009] According to the second aspect, a method for operating a MEMS component according to the first aspect is proposed, comprising the following steps: A first voltage is applied between the diaphragm and the first pair of electrodes to generate a first electrostatic force on the diaphragm, thereby reducing the restoring force generated when the diaphragm deflects toward the first pair of electrodes.

[0010] This invention is based on and incorporates the understanding that the aforementioned task is solved by a fixed electrode arranged at a distance from the diaphragm generating an electrostatic force on the diaphragm. This force is designed such that it reduces the diaphragm's restoring force and achieves mechanical softening of the diaphragm.

[0011] This results in a particular technological advantage: it enables the realization and operation of highly sensitive MEMS components, especially MEMS microphones or MEMS pressure sensors. In particular, it makes it possible to realize sensitive MEMS components with a small back-side volume. Furthermore, it also enables the realization of sensitive MEMS components with rigid yet low-noise diaphragms.

[0012] MEMS components include, for example, MEMS microphones. MEMS components also include, for example, MEMS pressure sensors, particularly MEMS relative pressure sensors.

[0013] MEMS microphones, for example, have a pressure equalization hole, particularly through the transducer structure of the MEMS microphone, through which a particularly quasi-static pressure equalization can be achieved.

[0014] Similarly, the implementation methods involving MEMS microphones are generally applicable to MEMS components, and especially to MEMS pressure sensors. Therefore, when referring to a “MEMS microphone,” it should always be understood as referring to a “MEMS component” or a “MEMS pressure sensor,” and vice versa.

[0015] In one embodiment, the MEMS assembly includes a fixed second pair of electrodes, wherein a diaphragm is disposed between the first pair of electrodes and the second pair of electrodes, wherein the second pair of electrodes is configured to generate a second electrostatic force that substantially counteracts the first electrostatic force when a second voltage is applied between the diaphragm and the second pair of electrodes.

[0016] This leads to a technical advantage, for example: the two electrostatic forces cancel each other out and the diaphragm does not deflect. This means that the resting point of the diaphragm is the same or approximately the same whether there is a voltage or not. This can be achieved, for example, by maintaining the same distance between the diaphragm and the electrode, and by having equal areas and the same voltage between the diaphragm and the electrode. For example, a change in one or two parameters can also be compensated for by a corresponding combination of a third parameter, such that the diaphragm is in the same position in the resting state whether there is an applied voltage or not. Parameters such as: the distance between the diaphragm and the counter electrode, the applied voltage, or the area.

[0017] In one embodiment, the MEMS assembly includes at least one mechanical stop for the diaphragm, which stops the diaphragm in the event of a restoring force generated when the diaphragm is deflected toward one of the counter electrodes, the restoring force being greater than the electrostatic force generated by the respective counter electrode when stopped on the mechanical stop.

[0018] Therefore, for example, it leads to technological advantages: resulting in high robustness against overload.

[0019] Typically, from a certain deflection point, the electrostatic attraction becomes greater than the restoring force. For example, this might occur when the deflection reaches 60% of the distance between the counter electrode and the diaphragm. If, during operation, the diaphragm is deflected more than 60% as currently exemplified, for example by a very large acoustic overload, the diaphragm becomes attracted to the fixed counter electrode, and the diaphragm typically cannot detach without countermeasures.

[0020] This provides a significant technical advantage by incorporating a stop: instability is eliminated under overload conditions. This stop is designed, for example, to mechanically stop before the point of instability is reached—that is, before the diaphragm is attracted to the fixed counter electrode and cannot detach without intervention.

[0021] In one embodiment, the MEMS component includes an overload detection device configured to detect an overload condition in which a diaphragm is attracted to one of the counter electrodes. The overload detection device is further configured to reduce or cut off the voltage applied to the corresponding counter electrode when an overload condition is detected.

[0022] This results in, for example, a technological advantage: high stability against overload. Therefore, a brief reduction or interruption of the voltage results in a technological advantage: the electrostatic attraction decreases or becomes zero, allowing the diaphragm to detach from the electrode again.

[0023] Therefore, it results in high stability against overload.

[0024] In one embodiment of a MEMS component, a diaphragm and one of the counter electrodes each have a comb structure with multiple comb-like fingers, wherein, starting from a defined deflection from the diaphragm toward the corresponding counter electrode, the corresponding comb-like fingers of the two comb structures engage with each other.

[0025] This leads to a technological advantage, for example: under overload conditions, as the diaphragm deflection increases, the electrostatic force becomes approximately constant, and thus the restoring force increases again, so that the point of instability is only reached when the surfaces of the two electrodes are very close. This point is, in particular, determined essentially by the size of the fingers and the spacing between them. Therefore, a significant improvement in the overload resistance of MEMS components can also be achieved through appropriate sizing design.

[0026] The basic idea behind the arrangement of the comb-like fingers is that, when the spacing between electrodes is large, the closely packed fingers are electrically very close to a flat plate due to stray field effects, and therefore exhibit force behavior inversely proportional to the square of the spacing between electrodes. If the fingers of the membrane sink into the fingers of the corresponding electrodes, and especially if the fingers are higher than the lateral spacing between the fingers, a constant force is generated between the first and second electrodes. In the transition region between these two regions, there exists a region with a very linear force behavior between deflection and force. By appropriately selecting the spacing between electrodes, the height of the fingers, the density of the fingers, the geometry of the grooves in the corresponding electrodes, and the applied voltage, this region can be well controlled, and it can be ensured that the resting position of the structure is also located in this region.

[0027] In one embodiment of a MEMS component, the height of the finger is at least one-quarter of the spacing width between the diaphragm and the corresponding counter electrode.

[0028] This results in a technological advantage: enabling a particularly suitable size design for the finger bodies.

[0029] The term "gap" can be used in place of the term "interval".

[0030] In one embodiment of a MEMS component, the horizontal gap between two fingers is less than twice the width of the gap between the diaphragm and the corresponding counter electrode.

[0031] This leads to, for example, a technological advantage: a particularly advantageous dimensional design for the arrangement.

[0032] In one embodiment of a MEMS component, the height of the finger is smaller than the spacing between the diaphragm and the corresponding counter electrode.

[0033] This leads to technological advantages, for example, resulting in a particularly advantageous dimensional design for the structure.

[0034] In one embodiment of a MEMS component, the width of the finger is less than twice the spacing width between the diaphragm and the corresponding counter electrode.

[0035] This results in a technological advantage: leading to a particularly advantageous dimensional design for the structure.

[0036] In one embodiment of a MEMS component, a diaphragm has a vibrating surface segment, and the fingers of the comb-like structure of the diaphragm are arranged electrically insulated from the vibrating surface segment.

[0037] This leads to a technological advantage, for example, that the detection region and the finger-like structure are electrically separated. Therefore, capacitance changes in the detection region can be easily detected. In this case, the voltage in the detection region can be independent of the voltage applied to the comb-like structure, thus simplifying electrical analysis and evaluation.

[0038] In one embodiment, the MEMS component includes another membrane that forms a double membrane with the said membrane, wherein one of the counter electrodes is disposed between the two membranes.

[0039] This results in a technological advantage: the creation of exceptionally sensitive MEMS components.

[0040] In one embodiment of a MEMS component, at least one of the diaphragm and the counter electrode is divided into a first region and a second region, which are either completely separated from each other or connected to each other but electrically insulated from each other.

[0041] This leads to a technical advantage, for example, that the diaphragm and / or counter electrode are each divided into two regions, which are either completely separated from each other or connected but electrically insulated from each other. Therefore, a constant voltage can be advantageously applied to the first region, and the second region can be used to detect the deflection of the diaphragm. Especially in particularly sensitive analytical evaluation circuits, it is often impossible to simultaneously apply a constant voltage to the circuit. For this reason, analytical evaluation schemes that maintain a constant charge on the electrodes are mostly used; therefore, it is advantageous to electrically separate the counter electrode or the diaphragm to isolate these two functions. The basic spacing between the diaphragm and counter electrode can be set according to the desired sensitivity and the available voltage, and selected according to the function.

[0042] For example, the region that generates a reaction force via the applied voltage can be positioned at the edge of the diaphragm in a slightly more rigid area, while the detection region can be positioned at the center of the diaphragm, i.e., in the region where the diaphragm moves more strongly when sound is applied and thus generates a larger signal. This allows for the advantageous generation of a large capacitance signal. Simultaneously, a correspondingly larger reaction force can be generated relatively easily at the edge via an increase in voltage, since the capacitance force is proportional to the square of the applied voltage.

[0043] The electrical separation between the detection region and the region with a constant voltage, as described herein, can be performed only in the diaphragm, can be performed only in the fixed electrode, or can be performed not only in the diaphragm but also in the fixed electrode.

[0044] The phrase "at least one of the diaphragm and the counter electrode" means "one of the diaphragm and / or the counter electrode".

[0045] Therefore, "one of the counter electrodes" refers, for example, to the first pair of electrodes or, for example, to the second pair of electrodes.

[0046] The implementation method relating to one of the counter electrodes also applies to the other of the counter electrodes, and vice versa.

[0047] In embodiments that describe only one pair of electrodes, a second pair of electrodes may be provided, which may be formed similarly to or differently from the first pair of electrodes.

[0048] The expression "at least one" means "one or more".

[0049] The embodiments or implementation methods described herein can be combined with each other in any way, even if this is not described in detail.

[0050] "Voltage" refers to "electric pressure".

[0051] "Electrode" refers to "counter electrode".

[0052] The implementation methods described herein are similarly applicable to MEMS components, and vice versa. This means that the technical functionality of this method is similarly derived from the corresponding technical functionality of the MEMS component, and vice versa. Attached Figure Description

[0053] The invention will now be further explained with reference to preferred embodiments. Herein lies: Figure 1 A cross-sectional view of a MEMS microphone. Figure 2 :chart, Figure 3 Another cross-sectional view of a MEMS microphone. Figure 4 :chart, Figures 5 to 7 : These are cross-sectional views of a MEMS microphone. Figure 8 :chart, Figures 9 to 22 The following describes different steps in the manufacturing method of a MEMS microphone. Figure 23 A MEMS microphone and Figure 24 Another type of MEMS microphone. Detailed Implementation

[0054] In the following text, the same reference numerals may be used for the same features. Furthermore, for clarity, it may be possible to specify that not all features in every figure have their own unique reference numerals.

[0055] The following explanation uses one or more MEMS microphones as an example to illustrate the scheme described herein. The corresponding implementation is generally applicable to MEMS components. This means that "MEMS component" can be used instead of "MEMS microphone".

[0056] Figure 1 The MEMS microphone 101 is shown.

[0057] MEMS microphone 101 includes a diaphragm 103, a fixed first pair of electrodes 105, and a fixed second pair of electrodes 107. The diaphragm 103 is arranged between the two pairs of electrodes 105 and 107.

[0058] In addition, the MEMS microphone 101 includes a carrier 109, which is, for example, a substrate, wherein two counter electrodes 105, 107 and a diaphragm 103 are attached to or arranged on the carrier 109.

[0059] A first layer 111 exists between the second pair of electrodes 107 and the diaphragm 103. A second layer 113 exists between the diaphragm 103 and the first pair of electrodes 105. A third layer 115 exists between the first pair of electrodes 105 and the carrier 109. An electrical contact portion 117 is provided on the second pair of electrodes 107, through which the second pair of electrodes 107 can make electrical contact.

[0060] Layers 111, 113, and 115 are oxide layers. These oxide layers serve as electrical insulation and also as sacrificial layers in the exposed areas. This means that the first layer 111 provides electrical insulation between the second pair of electrodes 107 and the membrane 103. This means that the second layer 113 provides electrical insulation between the membrane 103 and the first pair of electrodes 105. This means that the third layer 115 provides electrical insulation between the first pair of electrodes 105 and the carrier 109.

[0061] It should be noted that, in the sense of this specification, the sacrificial layer can be, for example, a dielectric layer, i.e., an electrically insulating layer. The dielectric layer can be, for example, an oxide layer, i.e., SiO2. The dielectric layer can also serve as a sacrificial layer for HF etching (HF: Fluorwasserstoff), i.e., etching with hydrofluoric acid.

[0062] Etching in the sense of this specification is, for example, HF etching.

[0063] The two counter electrodes 105, 107 have through holes 119, for example, for pressure balancing, allowing sound to reach the diaphragm 103 and causing the diaphragm to deflect due to sound pressure. The first counter electrode 105 is configured, for example, to generate a first electrostatic force on the diaphragm 103 when a first voltage is applied between the diaphragm 103 and the first counter electrode 105, thereby reducing the restoring force generated on the diaphragm 103 when it deflects toward the first counter electrode 105.

[0064] The second pair of electrodes 107 is configured, for example, to generate a second electrostatic force that substantially counteracts the first electrostatic force when a second voltage is applied between the diaphragm 103 and the second pair of electrodes 107.

[0065] exist Figure 1 In this configuration, the MEMS microphone 101 includes two fixed counter electrodes 105 and 107. Alternatively, the MEMS microphone 101 can be configured with only one counter electrode, such as a fixed second pair of electrodes 107, i.e., electrodes disposed above the diaphragm 103. In this configuration, the fixed second pair of electrodes 107 is referred to as the first pair of electrodes.

[0066] This, although not in Figure 1 It is shown in, but for example in Figure 5 Or also Figure 24 The configuration shown is therefore for a configuration in which the fixed counter electrode is arranged relative to the diaphragm 103 in a parallel plate arrangement. During operation, a constant voltage is applied between the diaphragm 103 and the fixed electrode. The mechanical reset force is well approximately proportional to the deflection of the diaphragm. Similarly, the diaphragm reset force caused by the limited back surface volume is well approximately proportional to the deflection of the diaphragm.

[0067] The electrostatic force between the movable diaphragm and the fixed electrode is inversely proportional to the square of the distance between the diaphragm and the fixed counter electrode. This means that the electrostatic force resists two restoring forces, and the greater the electrostatic force is as the diaphragm deflects.

[0068] This is based on Figure 2 The chart is shown.

[0069] Figure 2 Figure 201 is shown, including a horizontal axis 203 and a vertical axis 205. The diaphragm deflection relative to a rest position defined by zero is plotted on the horizontal axis 203. The vertical axis 205 is plotted in Newtons, i.e., force is plotted on the vertical axis 205.

[0070] Figure 207 indicates the curve of change in the diaphragm's restoring force. Figure 209 indicates the curve of change in the electrostatic force. Figure 211 indicates the curve of change in the sum of the restoring force and the electrostatic force.

[0071] Therefore, the applied voltage induces a force acting on the diaphragm, namely an electrostatic force, which results in a pre-deflection, indicated by reference numeral 213, exemplarily 15% in this case. As can be seen in Figure 201, the applied voltage causes the resultant force, i.e., the sum of the restoring force and the electrostatic force, to change less strongly as it deflects around the new rest point. The slope of curve 215 around its zero point is therefore less than the slope of curve 207 at its zero point. The change in this resultant force as it deflects around the new rest point is less pronounced than when deflecting around zero without an applied voltage.

[0072] The advantage of including a single fixed electrode arrangement is that this effect can be achieved simply by applying a constant voltage. No adjustment mechanism is required. Therefore, MEMS microphones can operate efficiently and simply. Noise caused by adjustment mechanisms can also be advantageously avoided.

[0073] according to Figure 1 The schematic diagram shows two fixed counter electrodes, with a voltage applied to the two electrodes 105 and 107 relative to the diaphragm 103. This advantageously results in two electrostatic forces canceling each other out and the diaphragm 103 not deflecting, such that the resting point of the diaphragm 103 is the same or approximately the same whether or not a voltage is applied.

[0074] This is exemplarily shown in Figure 401. Figure 4 The figure shows the plot. The horizontal axis 403 represents the deflection of the diaphragm relative to its rest position. The force is plotted again on the vertical axis 405. Reference numeral 407 indicates the curve of the change in the restoring force of the diaphragm 103. Reference numeral 409 indicates the curve of the change in the electrostatic force generated by the first pair of electrodes 105. Reference numeral 411 indicates the curve of the change in the electrostatic force generated by the second pair of electrodes 107. Reference numeral 413 indicates the curve of the change in the sum of the restoring force, the first electrostatic force, and the second electrostatic force.

[0075] As in Figure 4 As shown in Figure 401, the resting point of diaphragm 103 is the same or approximately the same whether there is a voltage or not.

[0076] In its simplest case, this can be caused by equal spacing between the diaphragm 103 and the two electrodes 105, 107, and by equal area and the same voltage between the diaphragm 103 and the fixed counter electrodes 105, 107. Alternatively, variations in one or two of these parameters, namely spacing, area, and voltage, can also be compensated for by a corresponding compensation for a third parameter, such that the diaphragm 103 remains in the same position in a static state, with or without an applied voltage.

[0077] It is possible that, in the case of a fixed counter electrode in a parallel plate arrangement, the electrostatic attraction becomes greater than the restoring force from a certain diaphragm deflection. For example, this may occur when the deflection reaches 60% of the distance between the counter electrode and the diaphragm. Therefore, if the diaphragm deflects more than 60% as exemplified here during operation, for example by a very large acoustic overload, the diaphragm is attracted to the fixed counter electrode and cannot be released without countermeasures. Therefore, it is advantageous, according to one embodiment, to identify such an overload condition, for example by providing an overload detection device, such that in the event of an overload, the voltage between the diaphragm and the fixed counter electrode is cut off or reduced, for at least a predetermined duration.

[0078] To achieve particularly high stability relative to overload, for example, fixed counter electrodes are provided on both sides of the diaphragm. Figure 1 As shown in the image.

[0079] A similar situation applies to a fixed electrode positioned between two mechanically coupled diaphragms, i.e., a double diaphragm arrangement. In such an arrangement, the point at which the system begins to become unstable and the diaphragm is attracted to the counter electrode is almost identical, but the deflection in the basic state is absent or significantly reduced. Therefore, a higher deflection and thus a higher overload are required to reach that point. Furthermore, a higher force compensation can be achieved with a double-electrode arrangement, such that, under the same force compensation, the point at which the system begins to become unstable occurs additionally later.

[0080] To achieve a system that does not exhibit instability under overload, overload-resistant stops are provided, wherein the stops are designed and sized such that they induce mechanical stopping before reaching the point of instability. This is exemplarily demonstrated in... Figure 3 Another MEMS microphone 301 is shown in the diagram. There, reference numeral 307 indicates such a mechanical stop. In this case, the mechanical stop 307 is disposed on the diaphragm 103.

[0081] In addition Figure 3As exemplarily shown, the second pair of electrodes 107 (but similarly applicable to the first pair of electrodes 105) is divided into a first region 303 and a second region 305, which are either completely separated from each other or connected to each other but electrically insulated from each other. Therefore, the two regions 303, 305 are electrically insulated from each other. Thus, a constant voltage can be applied to the first region 303, and the second region 305 can be used to detect the deflection of the diaphragm 103. Especially in particularly sensitive analytical evaluation circuits, it is often impossible to simultaneously apply a constant voltage to the circuit. For this reason, analytical evaluation schemes that keep the charge on the electrodes constant are mostly used; therefore, it is advantageous to electrically separate the counter electrodes to isolate these two functions. Depending on the desired sensitivity and the available voltage, it is also advantageous to select the basic spacing between the diaphragm 103 and the counter electrodes 107 or 105 differently according to their function.

[0082] For example, the region that generates a reaction force via the applied voltage can be arranged at the edge of the diaphragm 103 in a slightly more rigid region, while the detection region can be arranged at the center of the diaphragm 103, i.e., in the region where the diaphragm moves more strongly when sound is applied and thus generates a larger signal. This results in a large capacitance signal. Meanwhile, a correspondingly larger reaction force can be generated relatively easily at the edge by increasing the voltage, since the capacitance force is proportional to the square of the applied voltage.

[0083] Advantageous electrical separation between the detection region and the region with constant voltage can also be performed in the diaphragm, or in both the diaphragm and the fixed electrode.

[0084] exist Figures 5 to 7 Another MEMS microphone 501 is shown, having a diaphragm 103 and a fixed first pair of electrodes 503. The diaphragm 103 has a first comb-like structure 509 with a plurality of comb-shaped fingers 511 arranged on the vibrating surface segment 512 of the diaphragm 103. The fixed first pair of electrodes 503 has a second comb-like structure 505 with a plurality of comb-shaped fingers 507.

[0085] In this configuration, starting from a defined deflection of the diaphragm 103 toward the fixed first pair of electrodes 503, the corresponding comb-shaped fingers 507 and 511 of the two comb-shaped structures 505 and 509 engage with each other.

[0086] In the context of this specification, the comb-like structures of the finger-like bodies can also be referred to as columnar bodies or strip-like bodies.

[0087] Therefore, for example, an arrangement is proposed in which the height of the fingers is designed such that the individual fingers of the comb structure do not contact each other in the resting position of the diaphragm, but can sink into their respective grooves when deflected.

[0088] The basic idea behind this arrangement is that, in the case of a large gap between the counter electrode and the diaphragm, the closely packed columnar or strip-shaped bodies, i.e., finger-shaped bodies, are electrically very close to a flat plate due to stray field effects, and therefore have force behavior inversely proportional to the square of the gap between the diaphragm and the corresponding counter electrode.

[0089] This is based on Figure 8 Figure 801 is illustrated exemplarily. The deflection of the diaphragm from its rest position is plotted on the horizontal axis 803. The vertical axis 805 represents force. Reference numeral 807 indicates the curve of the change in the diaphragm's restoring force. Reference numeral 809 indicates the curve of the change in the electrostatic force generated by the counter electrode. Reference numeral 811 indicates the curve of the change in the sum of the restoring force and the electrostatic force.

[0090] A region of curve 809 is indicated by curly braces with reference numeral 812, in which the force behavior is inversely proportional to the square of the distance between the diaphragm and the electrode.

[0091] If the fingers sink into the corresponding grooves, and especially if the fingers are much higher than the lateral distance between the fingers and the corresponding counter electrode, a constant force is generated between the diaphragm and the counter electrode, as shown by the area marked by brackets with reference numeral 815 in the variation curve 809. In the transition region between regions 812 and 815, i.e., the region marked by brackets with reference numeral 813, this arrangement causes a very linear force behavior between deflection and force.

[0092] By appropriately selecting the spacing between the diaphragm and the counter electrode, the height of the fingers, the density of the fingers, the geometry of the grooves between the fingers, and the applied voltage, region 813 can be well controlled, ensuring that the resting position of this MEMS microphone, indicated by the arrow with reference numeral 817, is also located within this highly linear region.

[0093] A particularly advantageous arrangement for the fingers is, for example, having a height that is at least one-quarter the width of the gap between the diaphragm and the counter electrode.

[0094] A particularly advantageous arrangement for the fingers is, for example, that the horizontal gap between the fingers is less than twice the width of the gap between the diaphragm and the counter electrode.

[0095] A particularly advantageous arrangement for the fingers is, for example, that the height of the fingers is less than the spacing between the diaphragm and the counter electrode.

[0096] A particularly advantageous arrangement for the fingers is that the width of the fingers is less than twice the width of the gap between the diaphragm and the electrode.

[0097] The comb-like structure provides a particularly advantageous arrangement in which the instability point causing the diaphragm to adhere to the fixed counter electrode can be completely avoided, or only reached at significantly higher deflections. Such a device also advantageously enables a significantly more linear configuration of the electrostatic reaction force in the region surrounding the operating point, and thus a very linear signal even for large acoustic signals. Therefore, it is particularly advantageous to avoid unwanted harmonics that can arise from nonlinearities in the microphone system. Therefore, a three-dimensional structure of the diaphragm and counter electrode is proposed to alter the force behavior between the diaphragm and counter electrode.

[0098] Besides the good linearity of this arrangement, it has a particular advantage: under overload conditions, the electrostatic force approaches a constant value with increasing deflection (region 815), and therefore the restoring force increases again, so that the instability point is only reached when the corresponding surfaces of the diaphragm and the counter electrode are very close. This point is essentially determined by the height of the fingers. Therefore, significantly improved overload resistance can also be achieved with this type of arrangement.

[0099] Figures 9 to 22 Different time points in the manufacturing method for producing a MEMS microphone according to the scheme described herein are shown.

[0100] according to Figure 9 A functional layer 905 is deposited and structured on a substrate 901 or generally on a carrier. For example, a polycrystalline silicon layer is deposited. The functional layer 905 may form a counter electrode or a first diaphragm in a fabricated MEMS microphone. Currently, the functional layer 905 forms a first diaphragm. Between layer 905 and substrate 901, there is another layer, designated 903, which is a dielectric layer, i.e., an electrically insulating layer. The dielectric layer may, for example, be an oxide layer, i.e., SiO2. The dielectric layer may also serve as a sacrificial layer for HF etching (HF: Fluorwasserstoff), i.e., etching with hydrofluoric acid.

[0101] according to Figure 10 A sacrificial layer 1001 is deposited on layer 905 and structured such that grooves 1003 exist within the sacrificial layer 1001. The upper side of the sacrificial layer 1001 is indicated by reference numeral 1005.

[0102] Therefore, a sacrificial layer 1001 is deposited and structured. For example, an oxide layer is deposited as the sacrificial layer. For example, narrow trenches or holes, i.e., recesses 1003, are etched in the electrode region. For example, a plasma etching method is used, which can etch very vertical structures in the oxide, wherein the walls can deviate from the vertical line by less than 15°.

[0103] according to Figure 11 Functional layer 1101 is deposited on top 1005. Functional layer 1101 may be a polysilicon layer. Functional layer 1101 is removed, for example, by etching, such as CMP, down to top 1005, where CMP stands for "Chemical Mechanical Polishing".

[0104] according to Figure 12 Functional layer 1101 is removed up to the top of sacrificial layer 1001, 1005.

[0105] Another sacrificial layer 1301 was deposited, which is based on Figure 13 As shown. In this case, the other sacrificial layer 1301 is deposited on the upper side 1005. The other sacrificial layer can be, for example, an oxide layer.

[0106] For example, the two sacrificial layers are structured. Subsequently, another functional layer 1401, forming a fixed counter electrode, is deposited and structured, as shown in... Figure 14 The example is shown below. This other functional layer 1401 can be a polysilicon layer. A hole or trench 1403 is formed above the narrow trench or hole below, and is larger than the narrow trench or hole below. Preferably, this is done using a trench etching method that produces etched walls that deviate less than 15° from the vertical line. Subsequently, for example, both sacrificial layers are removed. Layer 1401 forms a diaphragm for a MEMS microphone.

[0107] exist Figure 14 The arrangement shown in the figure deposits a sacrificial layer 1501 and partially structures it (e.g., Figure 15 (As shown in the diagram). Trenches and holes 1503 are created, for example, smaller than the trench or hole 1403 below. An oxide layer may be deposited as a sacrificial layer 1501. Optionally, the oxide layer 1501 is planarized using a CMP method. The trenches or holes 1503 are etched, for example. A plasma etching method is used, for example, to etch a very vertical structure in the oxide, wherein the walls may deviate from the vertical line by less than 15°. Here, in particular, structuring is not performed over the entire height of the sacrificial layer 1501. This is performed, for example, via time-controlled oxide etching using a plasma process.

[0108] Deposit and structure another functional layer, such as a polysilicon layer. This can be done, for example, as follows: First, deposit a polysilicon layer 1601, then polish this layer down to the height of the sacrificial layer, that is, up to the top 1505 of the sacrificial layer 1501 (see...). Figure 16 Then, for example, entry into channel 1701 can be etched into sacrificial layer 1501 (see...). Figure 17 ), to generate, for example, corresponding support pillars. Then another functional layer is deposited and structured, particularly the polysilicon layer 1801 (see... Figure 18 This other functional layer 1801 forms a second diaphragm in the completed MEMS microphone.

[0109] Remove the sacrificial layer. Figure 19 The sacrificial layer is removed via one or more etched channels 1901. According to... Figure 20 The one or more etched entry channels 1901 are sealed by layer deposition 2001 or other methods, and negative pressure is surrounded, for example, in the cavity 2003 between the two diaphragms.

[0110] Contact surface 2101 can be formed on the surface of the upper diaphragm (see...) Figure 21 ).

[0111] according to Figure 22 Etching channel 2201 from the back side to the lower film.

[0112] Figure 23 The complete MEMS microphone 2301 is shown according to the manufacturing method described above and shown in the accompanying drawings.

[0113] Therefore, a first membrane 2303, i.e., functional layer 905, and a second membrane 2305, i.e. functional layer 1801, are formed by this method, thus forming a double membrane, wherein a fixed counter electrode, i.e., functional layer 1401, is disposed between the two membranes 2303 and 2305.

[0114] Reference numeral 2307 indicates the electrode region used to detect the deflection of diaphragms 2303 and 2305. Reference numeral 2309 indicates one or more regions of electrode 1401 used to compensate for stiffness, i.e., to generate electrostatic force to compensate for the restoring force of diaphragms 2303 and 2305.

[0115] Reference numeral 2311 points to the comb-like structures of diaphragms 2303 and 2305. Each comb-like structure 2311 has finger-like bodies 2313.

[0116] Reference numeral 2315 points to the comb-like structure of electrode 1401, wherein the comb-like structure 2315 has finger-like bodies 2317.

[0117] Figure 24Another MEMS microphone 2401 is shown, having a carrier 2403, a diaphragm 2405, and a fixed counter electrode 2407. Reference numeral 2409 points to a comb-like structure of the diaphragm 2405, wherein the comb-like structure 2409 has a plurality of fingers 2411.

[0118] Reference numeral 2413 points to an electrically insulating layer formed between the finger 2411 and the diaphragm 2405, such that the finger 2411 and the diaphragm 2405 are electrically insulated.

[0119] Reference numeral 2415 points to the comb-like structure of electrode 2407. The comb-like structure 2415 has a plurality of fingers 2417.

[0120] The scheme described herein is particularly applicable to fully differential microphone arrangements. In particular, such an arrangement also allows for the implementation of a very simple arrangement of counter electrodes on both sides of the diaphragm (see...). Figure 3 ).

[0121] This approach can be particularly applied to dual-film substrates with built-in counter electrodes (see...). Figure 23 ).

[0122] In particular, it is not important whether the cavity between the diaphragms is airtight or open.

[0123] The above-described embodiments or the solutions described herein are not limited to MEMS microphones, but are equally applicable to MEMS pressure sensors, especially MEMS relative pressure sensors. MEMS microphones, for example, compared to MEMS relative pressure sensors, may have an additional pressure balancing hole passing through the transducer structure, through which quasi-static pressure balancing can be achieved.

Claims

1. MEMS components, particularly MEMS microphones (101) or MEMS pressure sensors, have: Membrane (103) and The first pair of electrodes (105) are fixed. in, The first pair of electrodes (105) is configured to generate a first electrostatic force on the diaphragm (103) when a first voltage is applied between the diaphragm (103) and the first pair of electrodes (105), thereby reducing the restoring force of the diaphragm (103) when the diaphragm (103) is deflected toward the first pair of electrodes (105).

2. The MEMS component according to claim 1, comprising a fixed second pair of electrodes (107), wherein, The diaphragm (103) is disposed between the first pair of electrodes and the second pair of electrodes (105, 107), wherein the second pair of electrodes (107) is configured to generate a second electrostatic force that substantially counteracts the first electrostatic force when a second voltage is applied between the diaphragm (103) and the second pair of electrodes (107).

3. The MEMS assembly according to claim 1 or 2, comprising at least one mechanical stop (307) for the diaphragm (103), wherein the diaphragm (103) stops on the stop when a restoring force is generated when the diaphragm (103) deflects toward one of the counter electrodes (105, 107), the restoring force being greater than the electrostatic force generated by the respective counter electrode (105, 107) when it stops on the mechanical stop (307).

4. The MEMS component according to any one of the preceding claims, comprising an overload detection device configured to detect an overload condition, wherein, according to the overload condition, the diaphragm (103) is attracted to one of the counter electrodes (105, 107), wherein, The overload detection device is also configured to reduce or cut off the voltage applied to the corresponding counter electrodes (105, 107) when an overload condition is detected.

5. The MEMS component according to any one of the preceding claims, wherein, One of the diaphragm (103) and the counter electrode (105, 107) has a comb structure (505, 509) with a plurality of comb-shaped fingers (507, 511), wherein, starting from a determined deflection of the diaphragm (103) toward the corresponding counter electrode (105, 107), the corresponding comb-shaped fingers (507, 511) of the two comb structures (505, 509) engage with each other.

6. The MEMS component according to claim 5, wherein, The height of the fingers (507, 511) is at least one-quarter of the width of the gap between the diaphragm (103) and the corresponding counter electrode (105, 107).

7. The MEMS component according to claim 5 or 6, wherein, The horizontal gap between the two fingers (507, 511) is less than twice the width of the gap between the diaphragm (103) and the corresponding counter electrode (105, 107).

8. The MEMS component according to any one of claims 5 to 7, wherein, The height of the fingers (507, 511) is less than the spacing width between the diaphragm (103) and the corresponding counter electrode (105, 107).

9. The MEMS component according to any one of claims 5 to 8, wherein, The width of the fingers (507, 511) is less than twice the width of the gap between the diaphragm (103) and the corresponding counter electrode (105, 107).

10. The MEMS component according to any one of claims 5 to 9, wherein, The diaphragm (103) has a vibrating surface section (512), and the fingers (507, 511) of the comb-like structure (505, 509) of the diaphragm (103) are arranged electrically insulated from the vibrating surface section on the vibrating surface section.

11. The MEMS component according to any one of the preceding claims, comprising another diaphragm (103), the other diaphragm forming a double diaphragm with the diaphragm (103), wherein, One of the counter electrodes (105, 107) is arranged between the two diaphragms (103).

12. The MEMS component according to any one of the preceding claims, wherein, At least one of the diaphragm (103) and the counter electrode (105, 107) is divided into a first region (303) and a second region (305), which are either completely separated from each other or connected to each other but electrically insulated from each other.

13. A method for operating a MEMS component according to any one of the preceding claims, comprising the following steps: A first voltage is applied between the diaphragm (103) and the first pair of electrodes (105) to generate a first electrostatic force on the diaphragm (103) to reduce the restoring force of the diaphragm (103) when the diaphragm (103) is deflected toward the first pair of electrodes (105).

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