Micro-electromechanical structure for controlling a fluid

Abstract

A MEMS comprising a first layer comprising a first opening for passing a fluid. Further, a second layer is provided which is arranged opposite the first layer and comprises a second opening for passing the fluid. The second layer forms at least part of a layer stack together with the first layer, the layer stack having layers stacked in a stacking direction perpendicular to a substrate plane of the MEMS. A cavity arranged between the first layer and the second layer is provided and comprises an element movable along a direction parallel to the substrate plane, the element comprising at least a first position and a second position, wherein in the first position the fluid is prevented from flowing through and in the second position the fluid is able to flow through the cavity along the stacking direction.

Description

Technical Field

[0001] This disclosure relates to a MEMS for suppressing or allowing fluid flow through an opening in the MEMS. More particularly, this disclosure relates to an over-protection device or overpressure valve in a MEMS device. Background Technology

[0002] Overpressure can occur in different devices under different conditions and may cause material stress or even damage to the device.

[0003] Solutions for overvoltage protection are well known in the prior art. However, little is known about technologies based on the aforementioned MEMS technology. For example, document US 2015 / 041931 proposes a membrane-based protection device. In the open position, the membrane allows acoustic energy to pass from the outside of the device to the inside. In the closed position, the membrane contacts the outer surface of the opening to at least partially block acoustic energy from being transmitted from the outside of the device to the inside.

[0004] Document US 6,590,267 proposes a device based on the principle of an active deflectable actuator. The disclosed MEMS valve device is based on a membrane that can be actuated by an active deflectable electrode element and a biasing element. The membrane covers an opening and can be easily moved relative to the opening by the electrode element.

[0005] The drawback of known solutions is that their design is relatively complex.

[0006] Therefore, a simple and space-saving method to reduce overvoltage is needed. Summary of the Invention

[0007] One object of this disclosure is to provide a MEMS that allows for the flow of fluid in a simple and space-saving configuration, thereby allowing for the corresponding handling of fluid pressure.

[0008] This objective is achieved through the subject matter of the independent claims.

[0009] The core idea of ​​this disclosure is that it has been recognized that in-plane movement of a movable element can suppress fluid flow while allowing fluid flow at different locations on the same element. In-plane movement allows for simple mechanical structures that can also be implemented in a space-saving manner.

[0010] According to one embodiment, a micromolecular steam filter (MMS) includes a first layer having a first opening for fluid passage. The MMS includes a second layer disposed opposite to the first layer and including a second opening for fluid passage. The second layer, together with the first layer, forms at least a portion of a layer stack of the MMS, including a stacking direction perpendicular to a substrate plane of the MMS, the layers of which are stacked along the stacking direction. The MMS includes a cavity disposed between the first and second layers. A movable element is disposed in the cavity, movable along a direction parallel to the substrate plane, and includes a first positioning and a second positioning. In the first positioning, fluid flow is blocked, and in the second positioning, fluid flow through the cavity along the stacking direction is possible.

[0011] Further advantageous embodiments are the subject of the dependent claims. Attached Figure Description

[0012] Preferred embodiments of the present disclosure will now be discussed in more detail with reference to the accompanying drawings, in which:

[0013] Figure 1 A schematic perspective view of an MMS according to an embodiment is shown;

[0014] Figure 2a This is a schematic top view of a portion of an MMS according to another embodiment, wherein movable elements are connected to the sidewalls of the MMS on both sides via connecting elements;

[0015] Figure 2b Is with Figure 2a The illustrations in comparison show that fluid pressure exists within the MMS cavity;

[0016] Figure 2c Is with Figure 2b In the comparison diagram, the valve is open;

[0017] Figures 3a to 3c It is based on an embodiment of MMS and Figures 2a to 2c A comparative schematic top view, in which movable elements are suspended or fixed to the ends of beams via mounting areas;

[0018] Figure 3d It shows Figure 3a A schematic diagram of the state of the MMS, wherein the movable element is arranged in the first position;

[0019] Figure 3e It shows Figure 3d A schematic side sectional view of the MMS, in which the movable element is arranged in a second state;

[0020] Figure 4 An example is shown for explaining a specific size according to an embodiment. Figure 2a A schematic diagram of a portion of MMS;

[0021] Figure 5a The illustration shows a schematic function of displacement of the movable element of the embodiment relative to the applied pressure level;

[0022] Figure 5b A schematic diagram of a curve is shown to discuss how to achieve, for example Figure 5a The pressure occurring in the cavity shown is such that the pressure level can always be maintained to avoid potential damage to the structure;

[0023] Figures 6a to 6g This is a schematic top view of a possible implementation of the MMS or movable element according to an embodiment;

[0024] Figure 7a A schematic circuit block diagram of a system with a check valve according to an embodiment is shown; and

[0025] Figure 7b A schematic circuit block diagram of a system with a bidirectional overpressure valve function according to an embodiment is shown. Detailed Implementation

[0026] Before discussing the embodiments of this disclosure in more detail with reference to the accompanying drawings, it should be noted that the same elements, objects and / or structures, or elements, objects and / or structures having the same function or the same effect, have the same reference numerals in different drawings, such that the descriptions of these elements shown in different embodiments are interchangeable or applicable to each other.

[0027] The embodiments described below will be described in the context of several details. However, embodiments may also be implemented without these detailed features. Furthermore, for reasons of comprehensibility, circuit block diagrams will be used instead of detailed specifications to describe the embodiments. Additionally, unless the contrary is explicitly described, the details and / or features of the various embodiments can be readily combined with each other.

[0028] The embodiments described below relate to microelectromechanical systems (MEMS). MEMS can be fabricated using semiconductor materials (such as silicon) and, alternatively or additionally, other materials (such as metals).

[0029] The embodiments described herein specifically relate to micromechanical structures (MMS), where MEMS truly form subgroups because MEMS describe microelectromechanical systems.

[0030] As will be discussed in more detail below, similar embodiments may include sensor and / or actuator characteristics that enable an MMS to form a MEMS. However, other aspects of the embodiments described herein are not limited to such sensor and / or actuator characteristics. Therefore, such embodiments described herein as MEMS are not necessarily configured for using and / or generating electrical signals. Rather, the terms “MMS” and “MEMS” are used as synonyms in the context of the embodiments described herein.

[0031] The inventors have recognized that the solutions disclosed above are disadvantageously limited to removing the membrane from the layer plane of a MEMS layer stack. Furthermore, the membrane and the corresponding surface on which it is placed for sealing purposes must be matched to each other to achieve a sufficiently high sealing effect. In other words, a device must be provided in which opening and closing can be achieved by moving only a very small mass a short distance. A drawback is that these documents do not contain any features regarding how to implement a passive overvoltage protection device for MEMS.

[0032] However, this out-of-plane motion requires a complex valve structure to reliably interrupt fluid flow.

[0033] Figure 1 A schematic perspective view of an MMS 10 according to an embodiment is shown. The MMS 10 includes a first layer 12 and a second layer 14, which may be formed to include, for example, materials compatible with MMS / MEMS processes, such as semiconductor materials. For the sake of clarity, only layers 14 and 16 are shown in partial detail.

[0034] Optionally, layers 12 and / or 14 may comprise, partially or entirely, other materials, such as metallic materials, and / or may be formed based on doping to be conductive at least in the region. Alternatively or additionally, electrically insulating materials, such as oxide or nitride materials, may also be arranged. An optional third layer 16 may be arranged between the first layer 12 and the second layer 14, and its property of confining the cavity 18 between the first layer 12 and the second layer 14 may also be achieved in different ways, for example by introducing trenches or recesses in the first layer 12 and / or the second layer 14, so that the cavity 18 is still obtained when layers 12 and 14 are directly merged.

[0035] Layers 12 and 14 form at least a portion of layer stack 22, which in the present case also includes layer 16. Like layers 12 and / or 14, layer 16 (if present) may also be formed of MMS / MEMS compatible material.

[0036] Movable element 24 is disposed within cavity 18. Movable element 24 can be formed, for example, by selectively removing material from layer 16. Alternatively, movable element 24 can be introduced into cavity 18 and / or transported and secured there. In a preferred embodiment, movable element 24 is a curved beam or deformable element arranged to be suspended on one or both sides, and at least partially unsuspended, but preferably suspended relative to layers 12 and 14. For example, movable element 24 can be dissolved from layer 16, for example, by a selective etching process.

[0037] Therefore, layer stack 22 may include at least two layers, but may also include more layers, particularly since other layers may also be arranged to layers 12, 14 and optionally 16. Layers 12, 14 and / or 16 may be mechanically fixedly connected to adjacent layers (e.g., by a bonding process). Even if no new layers are formed here in the sense of layer stack, material may be produced for the interface between two layers.

[0038] Layer 12 includes an opening 26. Although the opening 26 is shown as a single opening connecting two opposing main sides 12A and 12B of layer 12, the opening 26 may also be implemented as two or more sub-openings.

[0039] Furthermore, layer 14 includes an opening 28 connecting a first main side (not shown) of layer 14 and a main side 14B arranged opposite to it. A fluid 32, which is a liquid and / or gas, can flow through the opening 26. The fluid 32 can also flow through the opening 28. This means that flow through a fluid path can be created between openings 26 and 28.

[0040] However, in Figure 1 In the positioning of the movable element 24, shown by solid lines, the movable element 24 obstructs the flow of fluid 32 from opening 26 to opening 28. This means that the flow of fluid 32 is blocked by cavity 18, particularly from opening 26 toward opening 28 and vice versa. Therefore, the movable element 24 extends within the cavity such that acoustic or fluid short-circuiting is suppressed between sub-cavities 341 and 342 formed on opposite sides of the movable element 24 within cavity 18. This means that the movable element 24 can have a small distance or no distance at all from the sidewalls 361 and / or 362, wherein the movable element 24 is arranged adjacent to or disposed on the sidewalls 361 and / or 362. Here, the sidewalls 361 and / or 362 need not be arranged opposite each other, and according to embodiments, they can also be implemented by a single sidewall, as will be described in the context of the embodiments.

[0041] Furthermore, the distance between the movable element 24 and layers 12 and 14 can be kept small to minimize fluid loss through the remaining gaps, thus preventing acoustic or fluid short circuits while still allowing movement of the movable element 24. Such gaps can be obtained, for example, by removing or omitting the bonding layer between layers 16 and 12 or 14, such as by selectively etching or recessing the respective layers.

[0042] The movable element 24 can also move from a first position shown by a solid line to a second position shown by a dashed line. The corresponding movement or change between positions 381 and 382 may include displacement of the movable element 24, but preferably includes deformation of the movable element 24.

[0043] MMS 10 may include layers arranged parallel to a so-called substrate plane, which in Figure 1 The plane referred to here is the x / y plane and can be understood, for example, as a plane arranged parallel to one or more layers 12, 14, or 16 during the manufacturing process of MMS 10. For example, the main side surfaces of the sheet can be arranged parallel to the x / y plane and thus define the substrate plane.

[0044] The direction z, which is perpendicular to the x / y plane, can be called the stacking direction. Layers 12, 14, and optional layer 16 are stacked along this stacking direction.

[0045] The movable element 24 varies between positions 381 and 382 in the x / y plane (i.e., in the plane).

[0046] For example, when transitioning to position 382, ​​the movable element 24 moves such that upon reaching position 382, ​​the movable element 24 is arranged beyond the opening 28, as shown by axis 42. In the first position 381, the movable element 24 can be positioned along the negative x-direction starting from axis 42, and in position 382, ​​the movable element 24 can be positioned along the positive x-direction starting from axis 42.

[0047] This exposes the fluid path between openings 26 and 28, thereby allowing fluid 32 to flow through cavity 18.

[0048] Furthermore, the flow along the stacking direction z is generated according to the orientation of openings 26 and 28, even though openings 26 and 28 can be displaced relative to each other along the x and / or y directions.

[0049] According to an embodiment, MMS 10 can be formed as an overpressure valve and configured to move the movable element 24 from position 381 to position 382 in the event of overpressure at the first layer (particularly the main side 12A). This can be understood as meaning that fluid 32 can enter, for example, through opening 26, and cause an increase in pressure in sub-cavity 341. When assuming a pressure difference relative to sub-cavity 342 (such as the main side 14B of layer 14), this increase in pressure can cause a force to be applied to the movable element 24, thereby causing a transition between positions 381 and 382.

[0050] Figure 2a A schematic top view of a portion of the MMS 20 according to an embodiment is shown. The explanation of the MMS 10 also applies to the MMS 20. The movable element 24 of the MMS 20 is connected to the sidewalls 16c of the layer on both sides via connecting elements 441 and 442.

[0051] Similar to movable element 24, connecting elements 441 and 442 can, at least to a relevant extent, restrict, inhibit, or prevent fluid flow between sub-cavities 341 and 342. This significantly inhibits the flow of fluid through sub-openings 261 and 262 toward opening 281.

[0052] The connecting elements 441 and 442 may optionally be implemented as a solid joint or other elastic element at the connection position 461 to layer 16 and / or the connection position 462 to movable element 24, in particular having a stiffness less than or equal to the stiffness of the deflectable element, and in particular allowing a certain degree of flexibility along the positive and / or negative x directions.

[0053] When the movable element 24 is arranged in the first positioning 381 Figure 2a The diagram in the image begins, Figure 2b A comparative illustration is shown, in which, for example, when fluid flows into sub-cavity 341 through sub-openings 261 and / or 262, a pressure 48 is formed in sub-cavity 341, i.e., a pressure difference relative to sub-cavity 342. However, this is equivalent to fluid flowing out from at least one of sub-openings 281, 282, and 283 in layer 14 (not shown here). The negative pressure in sub-cavity 342 generated here has the same effect as the overpressure in sub-cavity 341.

[0054] Figure 2c A schematic top view of MMS 20 is shown, in which movable element 24 is in a second position 382, ​​for example, caused by pressure 48. For example, the valve is open. This means that, for example, movable element 24 sweeps across opening 281, but it does not at least completely sweep across openings 261 and 262. On the one hand, the fluid path between openings 261 and 262 and opening 282 can be exposed through movable element 24, and fluid 32 flows accordingly.

[0055] When considering examples Figure 2a At the same time, the movable element 24 in different arrangements of openings and / or individual elements may also sweep across openings 261 and / or 262 and deflect in that direction so as to expose the passage between openings 261 / 262 on the one hand, and on the other hand, opening 281 may be an additional opening in layer 14.

[0056] In the context of this embodiment, "sweep" does not necessarily mean a certain arrangement in space in the sense of above or below, because such relative terms, such as front, back, left, right and other terms, are interchangeable in space, for example, by rotating the MMS.

[0057] Sweeping means that the movable element 24, which is positioned along the z-direction in a plane different from the openings 26 and 28, passes through the swept element.

[0058] According to embodiments, the range of movement of the movable element 24 may be directly related to the intensity of the pressure 48. However, a particularly preferred embodiment provides an MMS in which the second positioning 382 is also, in a sense, a stable position, which is in Figure 2b The pressure 48 is strong enough to cause the movable element 24 to deflect, but then a sudden jump occurs that may cause the movable element 24 to deflect or deform, for example... Figure 2c As shown, when the pressure level of 48 is first reduced, the deflection or deformation remains stable until a certain lower pressure level is reached, which will be discussed in more detail below.

[0059] from Figure 2c It can also be seen that, due to the change or deformation of the shape of the movable element 24, the connecting elements 441 and 242 deflect along the negative or positive x direction, which makes it possible to maintain less material stress or tension in the movable element 24 and / or connecting elements 441 and 442 when changing from position 381 to position 382 and / or returning.

[0060] therefore, Figure 2a The state (i.e., the first positioning) can be described as low-stress, or more simply, stress-free. This refers to a state where the level of mechanical stress is small or minimal. Figure 2c In position 382, ​​the movable element 24 may conversely be in a high-stress state. While reducing this mechanical stress, the movable element 24 can be changed from position 382 back to position 381. This means that, similar to a deflecting spring element, kinetic energy can be stored in the movable element 34 and / or connecting elements 441 / 442 to allow it to move backward.

[0061] However, even though the second positioning 382 has been achieved, further positioning can be considered as the pressure increases further, where, for example, an additional opening 28 enters the fluid path to increase the magnitude of the pressure increase. This means that it is possible that in the second positioning, the first region of the second layer is open to the fluid path, and in a further third positioning, a correspondingly increased region is open to the fluid path. The increase can be doubled, but it can also be any other multiple, and can be set, for example, by determining the dimensions of openings 282 and / or 283.

[0062] exist Figures 2a to 2c It can also be recognized that cavity 18 is subdivided into subcavities 341 and 342. Cavity 18 can also be subdivided into a greater number of subcavities by arranging additional elements. Subcavity 341 is arranged on the first side 24A of movable element 24. Subcavity 342 is arranged on the opposite side 24B. This does not necessarily require direct contact between the lateral region of movable element 24 and the fluid in the subcavity, as additional elements, such as movable plates, can also be arranged on the sides 24A and / or 24B. In this case, subcavity 341 is also fluidly coupled to opening 26 or sub-openings 261 and / or 262. When changing from positioning 381 to positioning 382, ​​the volume of subcavity 341 increases in the embodiment until subcavity 341 is also fluidly coupled to openings 281 and / or 282 and / or 283 in the opposite layer 14 to allow fluid 32 to flow through.

[0063] Preferably, increasing the sub-volume does not necessarily mean increasing the volume content of the sub-cavities. However, clearing the fluid path 52 can also be achieved when the sub-cavity 341 is reduced, for example, simultaneously on the side opposite to the movable element 24, for example if (instead of side 16c) another flexible element (such as a movable element connected in parallel). Conversely, it is sufficient if the opposing openings 281, 282 and / or 283 are fluidly coupled to the opening 261 or 262 by movement and / or deformation to achieve positioning 382.

[0064] In other words, Figures 2a to 2c A portion of MEMS 20 is shown in top view, comprising a deflectable element 24 connected to a surrounding substrate via a connecting element 44. Therefore, transition regions 461 and 462 are configured such that the stiffness in these regions is less than or equal to the stiffness of the deflectable element 24, the connecting element 44, and the substrate. In other words, deformation of the deflectable element 24 and the connecting region 44 within the elastic region of the material used is possible, allowing them to return to their initial positions after deflection. Three different states of MEMS 20 are shown. Figure 2aThe state shown is the stationary state of the deflectable element 24. It is arranged such that the entire cavity of the surrounding substrate 16, the bottom sheet 12, and the cover sheet (not shown) is subdivided into a first sub-cavity 341 and a second sub-cavity 342. The heights of the connecting element and the deflectable element roughly correspond to the heights of the cavities, minimizing the formation gap between the cover sheet, the moving element, and the bottom sheet. Sensitivity to slow pressure changes can be reduced by increasing the formation gap, i.e., with a larger gap (e.g., >10 μm), opening only occurs at sudden pressure spikes. Movement of the deflectable element and the connecting element can be suppressed without causing acoustic short circuits. In other words, volumetric flow between the two sub-cavities is prevented. Sub-cavities 341 and 342 are each connected to the surrounding fluid via an opening 26 in the bottom sheet 12 or an opening 28 in the cover sheet 14 (not shown). Fluid can enter or leak from the cavity through these openings.

[0065] Figure 2b The MEMS 20 is shown in top view during the time interval of the deflection method of the deflectable element 24. The pressure acting on the deflectable element 24 is shown at 48, which is generated by filling the cavity 341 through the opening 26.

[0066] Figure 2c The MEMS 20 is shown in top view during the time interval of the deflection method, where the applied pressure has exceeded the specific opening pressure of the deflectable element 24. The deflectable element 24 and the connecting element assume a new stress-induced position, which is maintained as long as the pressure value in cavity 44 is between the specific opening pressure and the specific closing pressure. Therefore, the volume of sub-cavity 341 increases, allowing the sub-cavity to be additionally connected to an opening 281 (not shown) in the cover sheet 14. Fluid can leak from sub-cavity 341 through this opening, resulting in a decrease in pressure within sub-cavity 341. If the pressure drops below the specific closing pressure, the deflectable element 24 and the connecting element 44 can assume a stress-free state and return to their initial position, as shown by, for example, reference... Figure 5a The subject of discussion.

[0067] Figures 3a to 3c A schematic top view of the MMS 30 according to an embodiment is shown. While comparable functionality can be achieved compared to the MMS 20, the movable element 24 can be fixedly suspended at the beam end and suspended from the sides 16a and 16b of the layer 16 via mounting areas 541 and 542. This makes manufacturing easier than with the MMS 20, but may result in higher material stress in the movable element 24. Meanwhile, as... Figure 3cAs schematically shown, a different bend line than that of MMS20 can be obtained in state 382, ​​which can be adjusted by implementing fixation in mounting areas 541 and / or 542. The movable element 24 here can be considered as a bending beam, and is implemented in state 382 in accordance with mechanical principles known to those skilled in the art, by orienting it relative to the bend line and / or implementing mounting areas 541 and / or 542.

[0068] exist Figure 3c The section line 56 of plane AA is shown in the figure, which will be referenced. Figure 3d and Figure 3e To discuss in more detail, Figure 3d and Figure 3e Each represents a schematic cross-sectional view of MMS 30 along the section axis AA.

[0069] exist Figure 3d In the diagram, MMS 30 is shown in a state where the movable element 24 is arranged in the first positioning 381, which is consistent with... Figure 3a and Figure 3b The diagram is similar. At the same time, due to the pressure p2 applied to the opening 262 of layer 12, there is a pressure gradient between sides 12A and 14B, where the pressure p2 is greater than the pressure p1 at layer 14 or in openings 281 and 283 or in side 14B.

[0070] Such as combination Figure 3c As described, the result can be that the movable element 24 changes to Figure 3e The second state 382 shown exposes the fluid path 52 through which the fluid 32 can flow, allowing the same pressure to be applied at both sides 12A and 14B of the MMS 30 and reducing... Figure 3d The pressure p2 is shown as pressure p3, and for example, pressure p3 decreases when compared to pressure p2, but is higher when compared to pressure p1. The same, different, or no pressure change may occur at opening 283, which may be affected by the time process and / or settings within the chamber. In another state not shown, the valve's closing pressure may cause the fluid path to remain open after the pressure has decreased. The remaining difference between p3 and p1 at opening 283 may be defined, for example, by the closing pressure.

[0071] Therefore, only opening 283 is shown in the cross-sectional view. It can be seen here that opening 283 is not necessarily required for the function of a valve or overpressure valve.

[0072] like Figure 2c As shown, in positioning 381, MMS 30 can include a first curved line, similar to MMS 20, which can... Figure 2a and Figure 3aAs seen in the top view. In the second positioning 382, ​​a second curved line can be obtained, which can be... Figure 2c and Figure 3c As seen in the image, the second curve can be geometrically different from the first curve. Here, when the corresponding suspension remains the same, asymmetrical forces can be obtained when changing from the first position 381 to the second position 382 on one hand and returning to the first position 381 on the other.

[0073] In other words, Figures 3a to 3c An alternative MEMS 30 is shown, in which the deflectable element 24 is directly connected to the surrounding substrate 16. The deflection process is no different from that of MEMS 20.

[0074] Figure 3d and 3d It shows along Figure 3e The cross-sectional view of section AA in the diagram. Figure 3d A cavity is shown formed in the plane of the device between the bottom sheet 12 and the cover sheet 14 and the surrounding substrate 16. This cavity is formed by two sub-cavities 341 and 342, separated from each other by a deflectable element 24. An opening 26 in the bottom sheet 12 is also shown connecting sub-cavity 341 to the surrounding fluid. An opening 28 is arranged in the cover sheet 14 and connects sub-cavity 342 to the surrounding fluid. Figure 3e The pressure compensation moment is shown after the pressure in sub-cavity 341 increases and the deflectable element 24 deforms to its stress-induced position. Here, sub-cavity 341 is connected to one of the openings 28 in the cover sheet 14, so the volumetric flow rate of fluid 32 in sub-cavity 341 transfers fluid from sub-cavity 341 through opening 281. Once ambient pressure is present in sub-cavity 341 or a lower pressure level is reached, the volumetric flow rate stops.

[0075] Figure 4 It shows Figure 2a A schematic top view of a portion of the MMS 20, used to explain possible but not necessarily required implementation standards and / or structural dimensions.

[0076] Figure 4 A deflectable element 24 connected to connecting element 44 via connection regions 462, 464 is shown. The surrounding substrate 16 is shown only in an abstract form. This illustration is intended to provide information about the geometric relationships between the elements. The deflectable element 24 is shown in a non-deflected state, i.e., the material is in a low-stress state. In this state, the minimum distance between element 24 and substrate side 16a is h. A The value is between 1μm and 100μm, preferably 20μm to 40μm. The distance to the substrate side 16b is h. B The value is between 1μm and 100μm, preferably between 20μm and 40μm. Under this deflection state, h...B will always be greater than h A . Further geometric parameters are the length l of the deflectable element 24 and the length b of the connecting element 44. The parameter l takes a value between 100 μm < l < 9 mm. The length l of the deflectable element 24 and the length b of the connecting element 44 are related as follows:

[0077]

[0078] In other words, the length of the deflectable element can for example be greater than the length of the connecting element. Furthermore, the deflectable element 24 is characterized by a radius of curvature R. This radius is generally in the range of 50µm < R < ∞, or -∞ > R > -50µm. The radius R and the length l of the deflectable element are related as follows:

[0079]

[0080] This means that the deflectable element may be a straight beam, or be implemented as an arc, such as a crescent shape.

[0081] The width of the deflectable element 24 is defined by t l . The ratio of the length to the width of the deflectable element is expressed by the following relation:

[0082]

[0083] In other words, the width of the deflectable element will always be less than its length.

[0084] Furthermore, the connecting element 44 comprises a width t b , the width t b has the following relationship with the length b of the connecting element 44:

[0085]

[0086] Therefore, t b can for example take a value less than b.

[0087] It should be noted that these elaborations are merely exemplary features for explaining the preferred embodiments.

[0088] The speed or rate of movement and / or reaction can be influenced via the parameter h A and / or h B . In the case where the values of h A and h B are relatively small, the valve will close in a delayed manner, and so-called squeeze film damping may occur. This allows, for example, setting a relatively short pressure pulse, comparable to an inert electric fuse of a valve that does not eliminate the entire pressure. When h A and h BWhen a relatively large value is selected, structural size can be sacrificed to increase sensitivity.

[0089] Figure 5a and Figure 5b This is used to discuss the multi-stable or at least partially stable implementations of the states of MMS 20 and MMS 30.

[0090] therefore, Figure 5a The diagram illustrates a schematic function of the displacement of the movable element 24 on the horizontal axis compared to the level of pressure 48, for example, as shown. Figure 2b , Figure 3b or Figure 4 As shown. Figure 5a The schematic variant illustrates the information shown. What remains constant is that the displacement y of the movable element is a function of the pressure p, i.e., y = f(p).

[0091] In the first portion 581 of the curve 62 shown, a direct relationship can be established between displacement (e.g., along the y-direction) and the occurring pressure 48 or pressure level. This ratio can be linear, but it doesn't have to be. A sudden jump can occur when the first pressure level 481 is reached, and for example, a [missing information] can be obtained. Figure 2c and Figure 3c Position 382 is shown. Displacement can occur in region 582 where a transition occurs between "closed" and "open", meaning that the two states can occur partially each and in combination with each other.

[0092] On the contrary, Figure 5a It can be understood that reducing the pressure from pressure level 481 does not cause the movable element to move backward instantaneously, but only when the second lower pressure level 482 is reached, which may also occur suddenly, like the jump at pressure level 481.

[0093] Using curves 641 and 642, Figure 5b This demonstrates how to achieve, as Figure 5a (Curve 642) The pressure occurring in cavity 18 can maintain a pressure level such that at pressure level 48 crit No further potential damage will occur. The pressure process in chamber 18 that may originate from the outside is shown in curve 641, which would be obtained without the function of an overpressure valve. However, curve 642 shows the pressure process in chamber 18 with a valve arranged.

[0094] Therefore, the pressure level is 48. crit This refers to the pressure level at which potential damage to the structure to be protected may occur. Pressure level 481 refers to the opening pressure of the valve structure. Pressure is expressed relative to ambient pressure p0. For example, when headphones are plugged in or removed, overpressure may form in the headphones.

[0095] For reference Figure 5a As discussed in the discussion of MMS 10, 20, and 30, the MMS can be implemented such that when a first pressure level of fluid is applied to the first layer, a change from a first position to a second position occurs, and when a second pressure level of fluid is applied to the first layer, a change from the second position back to the first position occurs, wherein the first pressure level is greater than the second pressure level. The change of position (especially the return to the first position) should not be understood, in particular, as a continuous decrease due to a continuously decreasing pressure, but rather as, according to the embodiment, a sudden return motion (bounce) when the stabilizing force in the movable element 24 is no longer sufficient to maintain the previously stable position of the second position 382. This means that when the first pressure level has been reached, the change from the first position 381 to the second position 382 can be sudden or at least substantially sudden. When maintaining the first position 381 (see...) Figures 5a to 5b At this point, a subsequent slight decrease in the pressure level can cause the movable element 24 to initially remain in the second position 382. A potential sudden movement back to the first position 382 is only possible once the pressure level has been sufficiently reduced. Figure 5a As can be understood, the closing pressure 482 can be less than the opening pressure 481. The embodiments allow for the free implementation or limitation of these two pressures relative to each other. Therefore, appropriate designs can be made according to the specific requirements of the valve being implemented or the corresponding application.

[0096] According to an embodiment, the movable element 24 can be configured to receive a deformation force from a first pressure level to deform the movable element 24 to a second position 382. Upon transition to the second position 382, ​​the material stress in the movable element 242 can initially increase and then decrease, meaning the stress level can decrease. This implies that after an initial increase, the material stress can decrease again with the sudden movement to the second position 382, ​​as is known in, for example, bistable, tristable, or multistable deformation of deformable elements. However, unlike bistable elements, the movable element 24 in the embodiment is implemented such that a sufficiently large pressure reduction is sufficient to achieve a movement back to the stable first position 381. This means that the movable element 24 can be configured to take a stable state, i.e., position 382, ​​based on the reduction in material stress, and this stable state can be maintained from the first pressure level until a second pressure level or lower is obtained.

[0097] The movable element 24 can be configured to change to a second position 382 based on an increase in fluid pressure at the first layer (i.e., the first side of the movable element 24), to initially maintain the position at the second position when the pressure decreases until a second pressure level is reached. This rearward movement can be based on mechanical stress, which is not solely due to pressure. This means that the energy required for the rearward movement, or the energy required for it, when taking the second position 382 from the first position 382, ​​can be stored in the material of the movable element 24 and / or its suspension.

[0098] In the embodiments described herein, the pressure difference between the first and second layers is emphasized. These pressure differences are particularly important in preventing acoustic or fluid short-circuiting between the outer fluid layer or between the first layer 12 and the second layer 14. This is especially true when the MMS described herein is used unidirectionally or bidirectionally as a functional structure in a system, for example, as an overpressure valve for such a system. Headphones, for example, can be considered as such systems, where, for example, when considering the human ear canal, acoustic short-circuiting of such a structure can be prevented.

[0099] Figure 5a The deflection behavior of the deflectable element 24 according to the embodiment is illustrated graphically. The pressure in the first sub-cavity 341 relative to the displacement or deformation of the deflectable element 24 is shown. It should be understood that after exceeding the opening pressure, the deflectable element 24 deforms and remains in a so-called springback position, i.e., position 382, ​​until the pressure in the first sub-cavity 341 takes a value between the opening and closing pressures. Once this value decreases below the closing pressure, the deflectable element 24 returns to its original position, i.e., position 381. This is also referred to as rebound. The closing pressure will always be less than the opening pressure, where the closing pressure can also be negative.

[0100] By using the valves of the MMS described herein, the pressure process within the chamber can be regulated so that pressure levels that could potentially damage the structure being protected are not reached. See [link to relevant documentation]. Figure 5b Once the valve is opened, the pressure typically does not increase further but decreases until it reaches or is close to the closing pressure, depending on the implementation (see solid line).

[0101] As already discussed, for example using MMS 20 and MMS 30, the movable element 24 may include a beam structure suspended on both sides, which bends along a first direction (e.g., the positive y-direction) relative to an undeflected reference position (e.g., a straight, undeformed, or stress-free beam structure). Even though the embodiments do not preclude pre-deflection of the element during or after manufacturing, the deflectable element 24 may preferably have already been manufactured in the form shown (e.g., by a selective etching process such as an etching process, or a selective generation process that adds material). The movable element 24 may be configured to perform deflection relative to the reference position in a second direction when changed to position 382, ​​which is, for example, opposite to the first direction, i.e., the negative y-direction.

[0102] Even if the aforementioned reference positioning is not always necessary, situations may arise where this reference positioning needs to be overcome. For example, although MMS 20 suggests connecting elements 441 and 442 for simplicity, Figures 3a to 3c The MMS 30 can also be implemented using a fixed suspension, which may require higher forces to maintain positioning 382, ​​but also allows for a more stable position within positioning 382. In particular, stress relaxation of the movable element can be maximized. Stress relaxation allows for bistable operation and can occur when pressure is applied to stress or deform the first bending element. Due to the suspension, in Figures 3a to 3c In this system, stress relaxation can be set to adjust the relationship between opening and closing pressures.

[0103] According to an embodiment, the movable element 24 can be held at least on a first side at the cavity wall of the cavity 18 by retaining elements 441 and 442 associated with the first side. Figures 2a to 2c In the diagram, this is shown on both sides or at both ends of the beam structure for the movable element 24. The movable element 24 can be bent in the first positioning 381 and is configured to initially resist bending when changed to positioning 382. The retaining elements 441 and / or 442 can be implemented as spring suspensions for the movable element.

[0104] Even though MMS 20 is shown such that the movable element 24 is held by corresponding retaining elements 441 and 442 at both the first side / end and the second side / end opposite to the first side, asymmetrical or unequal mountings may also be used, as will be discussed below. Specifically, refer to... Figure 1 It can also be installed on one side or suspended.

[0105] The following will refer to Figures 6a to 6g Some possible implementations of the MMS or movable element 24 are discussed. Even though different advantageous implementations are described in different figures, these implementations can be easily combined with each other.

[0106] Figure 6a A schematic top view of a portion of the MMS 601 according to an embodiment is shown. Compared to the MMS 20, the movable element 241 may include a localized weakening portion 66. The localized weakening portion 66 may be implemented, for example, as additional material or an additional axial extension. Figure 6a In the example, this is relative to the outer arc of the remaining movable element 24 (which is in Figure 2a (As illustrated in the example), an inner arc pointing in the opposite direction along the positive y-direction and thus in the negative y-direction.

[0107] exist Figure 6b The diagram shows a schematic top view of a portion of MMS 602, where the movable element 242 includes a wave-like or zigzag bend compared to MMS 20. In the illustrated positioning 381, the bend projected onto the substrate plane may include multiple continuous (wave-like) or discontinuous (zigzag or curved) variations in the sign of the radius of curvature. Therefore, the radius of curvature 681 may include a first sign relative to the curvature along the positive x-direction and an opposite sign for subsequent radii of curvature 682 along the x-direction.

[0108] Figure 6c A schematic top view of a portion of the MMS 603 according to an embodiment is shown, wherein the movable element 243 may include a plurality (at least two, at least three or more) of layers 721, 722 and 723 arranged adjacent to each other parallel to the substrate plane. At least two layers may include different materials, different potentials, different material thicknesses, etc., but are implemented to be equal in one or more of these properties. This means that, in embodiments, two layers in a plurality of layers may also be spaced apart from each other at least in regions, with layers in discrete regions mechanically or loosely fixed to each other without distinguishing them from one another.

[0109] The movable element 243 can be used, for example, as a multilayer component or composite component using metamaterials, piezoelectric materials, or special geometries. Metamaterials can be understood as materials that can be generated from small periodic patterns, possessing effective properties that cannot be found in this form in naturally occurring materials (such as tensile materials or phononic crystals).

[0110] For example, a so-called nanoscale electrostatic actuator (NED) can be referred to as a special geometry in which layers are electrically insulated from each other and / or mechanically fixed to each other, at least in discrete regions, and an electrostatic attraction is allowed by applying a potential difference between two adjacent layers, which can allow the deflection of the movable element 243 and / or serve as a sensor feature for detecting deflection generated by pressure. Thus, by using a potential, when the movable element 243 is designed accordingly, for example, in addition to the pressure of a fluid, an electrostatic force can also be introduced into the movable structure 243 to set the potential. Figure 5aAdjustment of the curvature and / or switching points.

[0111] Figure 6d A schematic top view of at least a portion of the MMS 604 according to an embodiment is shown. Compared to the MMS 20, the MMS 604 includes a mechanical element 74 extending from cavity 216c into cavity 18 and configured to limit the deflection of the movable element 24, or another movable element described herein, through mechanical contact with the movable element 24 starting from positioning 381. This allows for the avoidance of damage to the movable element 24 due to excessive pressure, as deflection exceeding the desired positioning 382 can be limited.

[0112] Mechanical element 74 may be cuboid or shaped differently as needed, such as circular, rod-shaped, or comprising several parts.

[0113] Figure 6e A schematic top view of component MMS 605 according to an embodiment is shown. Here, the movable element 24 is active and configured to receive a drive signal, which can be considered as the potential difference between signal sources 761 and 763 and / or 762 and 763. Even though signal sources 761 and 763 are shown such that separate potentials can be applied to a first electrode 781 disposed at cavity wall 16d and an electrode 782 disposed opposite at cavity wall 16c, signal sources 761 and 762 can also apply the same potential or potentials of equal magnitude and be driven, for example, in a time-alternating manner.

[0114] Electrodes 781 and / or 782 may be implemented, for example, at or within layer 16. For example, conductive material may be arranged for this purpose and / or conductivity of the material in layer 16 in the region may be generated, for example, by doping with semiconductor material.

[0115] Electrodes 781 and 782 can be arranged such that capacitors can each be combined with movable element 24 to form a capacitor. The direction of action of the capacitors is arranged to be parallel to the substrate plane, i.e. parallel to the x / y plane, so that the corresponding potential between electrode 781 and movable element 24 and / or electrode 782 and movable element 24 causes support and / or resistance to the deflection of movable element 24 in the positive or negative x direction.

[0116] Here, MMS 605 can be obtained as a valve, which can be about Figure 5aOne or more switching times can be electrostatically set, or even electrically actuated. According to the illustrated embodiment, the movable element 24 can be actively implemented and used to receive a drive signal, and is configured to change the pressure sensitivity of the fluid based on the drive signal for changing from position 381 to position 382 (not shown), and vice versa. Alternatively or additionally, movable elements with different signal amplitudes can also perform changes from the first position (381) to the second position (382) and / or vice versa based on an actively controlled drive signal (761 to 763). It should be noted that only three beam structures are exemplary, but different numbers of beams can be implemented, such as at least one, at least two, or more than three, for example, four, five, or six or more.

[0117] If already combined Figure 6c The electrode structure of the MMS 605 discussed can also be used for sensor functions, such as forming a sensor element implemented to provide a sensor signal associated with the deflection state of the movable element 24. Alternatively or additionally, corresponding sensor elements may be provided in addition to signal sources 761, 762, and 763. According to embodiments, the MEMS may include a shut-off control loop (feedback / regulation) to set the characteristics of the movable element based on a determined deflection or determined behavior.

[0118] This means that a control device 79 can be provided, which is configured to drive signal sources 761, 762 and / or 763, and can optionally be configured to acquire a sensor signal 81 indicating the deflection state. It can also be implemented to acquire only the sensor signal 81 without providing voltage sources 761, 762 and / or 763.

[0119] Figure 6f A schematic top view of a portion of the MMS 606 is shown in the figure, in which the dimensions of the region of opening 26 are different from the dimensions of the region of opening 28. Here, the size of the region is understood as an area, which can be, for example, expressed in terms of n... 2 μm 2 or mm 2 express.

[0120] Alternatively or additionally, the shape of the region of opening 26 may differ from that of opening 30. For example, opening 26 may be rectangular, while opening 28 may be trapezoidal. These two differences may be implemented independently of each other or together. Although the different dimensions of the regions of openings 26 and 28 can also set the attenuation behavior with respect to a system using MMS, the region shapes may, for example, be adjusted to bends or positions of the movable element 24 in the first and / or second positioning.

[0121] Figure 6gA schematic top view of a portion of the MMS 607 according to an embodiment is shown, wherein the movable element 24 is suspended asymmetrically. While a connecting element 44 (which may extend along the positive y-direction toward the substrate plane 16 (e.g., side 16d)) is provided at the first end 821, the opposing second end 822 may be fixedly suspended, or, as shown, formed by a flexible connecting element 84 or an element implemented as a spring element, having characteristics substantially similar to the connecting element 44, but may include different orientations (e.g., parallel to the x-direction), different thicknesses, and / or lengths. In other words, Figure 6g An MMS with asymmetrical suspension is shown, wherein the movable element 24 remains suspended on both sides.

[0122] Figures 6a to 6g Several alternative embodiments of MMS / MEMS are illustrated, differing from the implementation of the deflectable element. This illustration is intended to demonstrate how the design of the deflectable element can significantly influence deflection and response behavior. For example, different response pressures can be achieved through locally weakened beams (see...). Figure 6a ) or complex geometry (see Figures 6a to 6b Alternatively, the volume of the setting can be reduced to address / set the issue in response to the pressure within the sub-cavity. The stiffness, mass, and attenuation of the deflectable element can be manipulated by using multilayer, composite, or metamaterials as alternative materials to the deflectable element (see [link to relevant documentation]). Figure 6c This allows for better matching of the opening pressure, closing pressure, opening process, intrinsic frequency, and response time for the corresponding application. Additionally, this material can generate extra internal stress in the deflectable element, which can alter the force balance to achieve, for example, even faster response. Piezoresistive materials can also be used to generate a defined electrical signal for detecting the opening. Capacitive feedback is also possible when using NED-based deflectable elements.

[0123] Figure 6d The MMS / MEMS proposed embodiment is equipped with a stop 74 for the deflectable element 24. Advantageously, the volume of the corresponding sub-cavity can be set more precisely when pressure is applied. Furthermore, the induced voltage in the material of the deflectable element 24 in the deflected position is minimized, thereby increasing the lifetime of the MEMS component.

[0124] Figure 6eThe MMS / MEMS embodiment illustrates an actively deflectable element. Here, for example, a portion of the surrounding substrate is connected to first and second signal voltages. A third electrical signal is provided to a third portion of the substrate, also connected to the deflectable element 24. All signals are connected to a corresponding control device 79 and are electrically isolated from each other by electrical insulating elements. This embodiment aims to provide a settable overpressure valve. By applying a corresponding signal, the stiffness of the deflectable element can be affected, thereby influencing the response behavior. Furthermore, the deflectable element can be held in one of its two positions.

[0125] Figure 6f The MMS / MEMS embodiment illustrates the arrangement of large openings 26 and 28, and implies that those skilled in the art can adjust the implementation of the openings in the cover sheet and bottom sheet according to the object set.

[0126] Figure 6g The MMS / MEMS embodiment illustrates an asymmetrical arrangement of the connecting element 44. Here, the deflection behavior of element 10, particularly when it moves back to its initial position, can be positively affected (hysteresis).

[0127] Figure 7a A schematic circuit block diagram of a system 701 according to an embodiment is shown. System 701 includes a MEMS device (MEMS BE) 861 according to an embodiment of this disclosure, having a MEMS valve 88, which may be formed as, for example, MMS 10, 20, 30, 601 to 607, or include such MMS / MEMS. Due to the orientation of the MEMS device 861, the valve direction 92 can be set by setting the orientation of layers 12 and 14, since MM 10, 20, 30 and 601 to 607 may include a flow direction from layer 12 to layer 14.

[0128] With the aid of MEMS device 861, volume or chamber 94 can be separated from another volume or external environment 96. While the pressure p can be at least substantially constant in environment 96, for example, pressure changes can occur in volume 94. For example, if so-called in-ear headphones or different forms of headphones are inserted into or removed from the ear canal, a corresponding pressure change can occur. The pressure difference can be generated by the confined volume and relatively significant volume changes.

[0129] refer to Figure 5aA trigger pressure can be set, for example, similar to a first pressure level, such that it is higher than 1500 Pa or a dp threshold of 1500 Pa. As long as the actual pressure difference dp is below 1500 Pa, valve 88 can remain in the first position, while when the pressure exceeds this, valve 88 is triggered, which is to be avoided in the system implementation to reduce the pressure in volume 94. The overpressure valve described herein can be configured to trigger at a pressure of up to 5000 Pa, preferably up to 2000 Pa, and particularly preferably about 200 Pa.

[0130] Figure 7b A schematic circuit block diagram of system 702 according to an embodiment is shown. System 702 or MEMS device 862 may include two valves 881 and 882 having the MMS / MEMS described herein, compared to system 701 which provides valve 88 for unidirectional pressure reduction. When the exemplary reference volume 84 can represent an example of an earphone with an ear volume, system 701 may be implemented such that when the earphone is inserted into the ear canal, the overpressure formed there is reduced by valve 88.

[0131] When it is removed, a corresponding negative pressure may be created, and valve 88 may only be able to correct this negative pressure to a limited extent.

[0132] Therefore, two valves with opposite valve directions 921 and 922 are provided in system 702 or MEMS device 862. The two valves 881 and 882 may include equal trigger pressures, such as 1500 Pa, one in the positive direction of valve 881 and the other in the negative direction of valve 882.

[0133] Although a system 702 with two distinct valves adapted to flow in opposite directions is shown, embodiments also provide bidirectional MEMS valves. Here, for example, refer to... Figure 2a The first fluid path 52 is provided between opening 26 and opening 28, see [reference]. Figure 2c It is adjusted to reduce the fluid pressure at the first layer 12 and is blocked by the movable element 24 in the first positioning 381 of the movable element 24. The MMS may include a second fluid path configured to reduce the fluid pressure at the second layer by delivering fluid toward the first layer (i.e., in the opposite direction), wherein the movable element 24, or another element movable parallel to the substrate plane, is configured to sometimes inhibit fluid flow through the second fluid path and sometimes allow fluid flow through the second fluid path. Thus, for example, it may be provided Figures 2a to 2c or Figures 3a to 3cThe movable element 24 is positioned in a third position to connect at least one opening in the first layer 12 to at least one opening in the second layer. Alternatively or additionally, an additional movable element of a corresponding implementation may be provided, configured to connect at least one opening in the first layer 12 to at least one opening in the second layer when the additional element includes a corresponding second position.

[0134] The embodiments relate to a system including an MMS / MEMS according to the embodiments described herein. Such a system may, for example, include an overpressure valve having a corresponding MMS, or the MMS may be implemented as an overpressure valve. Exemplary systems are, for example, headphones or any other implementation including an overpressure valve having the features described herein.

[0135] Figure 7a and Figure 7b The basic function of the disclosed overpressure valve is illustrated. Therefore, the chamber exemplarily represents the volume within the external auditory canal between the MEMS device and the eardrum. The pressure within the ear canal may undergo sudden changes due to various events, such as removing or inserting the MEMS device into the ear canal. Figure 7a The illustration shows the insertion of a MEMS device and the resulting increase in pressure, which can be compensated for by opening a valve. Figure 7b This illustrates a situation where negative pressure can occur very suddenly in the ear canal, and the pressure must be compensated for.

[0136] The objective of this invention, achieved through embodiments, is to provide a device for protecting the internal space of a MEMS-based acoustic transducer from excessively strong or sudden pressure differences. Such pressure differences can subject actuators arranged within the MEMS to high mechanical stresses, potentially leading to their destruction.

[0137] The solution disclosed herein is implemented by a device preferably implemented passively and arranged within the cavity of a MEMS-based acoustic transducer. Passive deflection elements are arranged within the cavity and connected to the surrounding substrate, such that they divide the cavity into two sub-cavities. Therefore, a lower outlet is associated with the first sub-cavity, and an upper outlet is associated with the second sub-cavity.

[0138] When a certain pressure, for example, might suddenly occur and act on the passive deflectable element, it will deform and adopt a stress-induced geometry. As long as the pressure difference is maintained, the stress-induced force and the pressure-induced force will be in balance, and the passive deflectable element will remain in that position. If the pressure-induced force decreases, the stress-induced force will dominate, and the deflectable element will return to its low-stress state.

[0139] When fluid enters the cavity through an opening in the cover sheet, it creates a pressure differential within the cavity. If this sudden pressure fluctuation exceeds a defined opening pressure, the passive element will deform, causing the geometry of one or more outlets to change from one sub-cavity to another, thereby enabling / causing pressure compensation between outlets associated with the same sub-cavity.

[0140] This disclosure relates to a micromechanical system (MMS) or microelectromechanical system (MEMS) configured to dissipate overpressure from the ear canal and speaker, for example, that may occur in a speaker disposed in a user's ear canal. For example, overpressure can occur when a speaker is introduced into or removed from the ear canal. Such sudden overpressure can damage acoustic transducers because it can cause mechanical deformation of the transducer. Furthermore, this MEMS-based overpressure valve is not limited to this application area. In other words, this disclosure proposes a protective device for acoustic transducers in the event of pressure changes, thereby preventing mechanical overstress. Additionally, this disclosure may also include other features for other MEMS-based devices, such as pumps, switches, and adjustable capacitors.

[0141] The MMS / MEMS device proposed herein is a stack of layers consisting of at least one substrate layer, in which optional electrodes and passive components are arranged. Additional layers involve a bottom (also referred to as a disposal sheet) and a cover (also referred to as a cover sheet). Both the cover sheet and the disposal sheet are attached to the substrate plane via a material-to-material method (preferably a bonding method), thereby forming an acoustically sealed intermediate space within the device. The deformable device deforms within a gap corresponding to the device plane; in other words, the deformation is in-plane.

[0142] These layers may include, for example, conductive materials, such as doped semiconductor materials and / or metallic materials. The layer arrangement of conductive layers allows for simple implementation because electrodes (for deflectable elements) and passive elements can be formed by selectively dissolving from the layers. Where non-conductive materials must be provided, these materials are deposited using deposition methods.

[0143] This means that the movable element 24 can be configured to alternately include a first positioning 381, a second positioning 382, ​​and a third positioning 383, i.e., one of the previously mentioned positions. A higher amount of fluid can flow through the cavity in the third positioning 383 than in positioning 382.

[0144] This disclosure provides design guidelines for implementing overpressure valves. Therefore, the inventors have decided to associate geometric parameters in order to provide a device based on the associated design parameters. Several aspects of this disclosure relate to the following:

[0145] MEMS includes deflectable elements.

[0146] The deflectable element has a stress-free (mechanical) basic position.

[0147] When the opening pressure in the first sub-cavity is exceeded, the deflectable element is in a new position, thereby generating mechanical stress in the material.

[0148] As long as the pressure is maintained, the force caused by the pressure and the force caused by the stress acting on the deflectable element are balanced. This means that the deflectable element will remain in its position.

[0149] If the pressure drops below the shut-off pressure, the stress-induced force is greater than the pressure-induced force, and the deflector element returns to its low-stress state.

[0150] To optimize the opening pressure or opening path, sawtooth and wave geometries can be envisioned.

[0151] There may be more than two stable positions; for example, the beam creates a small opening with a limited flow rate under the first opening pressure, and suddenly opens a large opening only under the second opening pressure.

[0152] Example:

[0153] The beam can be fabricated using coating techniques (such as polycrystalline silicon) that do not start at stress. This strategy may be advantageous.

[0154] Example:

[0155] In one embodiment, the deflectable element may be actively deflectable.

[0156] o For example, in embodiments such as ANED (asymmetric nanoscale electrostatic actuator, such as two beams connected to each other), LNED (lateral nanoscale electrostatic actuator, as described, for example, in WO 2012 / 095185 A1), or BNED (balanced nanoscale electrostatic actuator, as described, for example, in WO 2020 / 078541 A1).

[0157] It is preferable to use DC voltage to actively set the opening and closing pressures via additional electrostatic force.

[0158] o Actively turned on and off by additional electrostatic force, DC voltage, or AC voltage.

[0159] Example:

[0160] The deflectable element can generate a signal to indicate opening and closing.

[0161] o Capacitive feedback through electrodes arranged in the cavity

[0162] Capacitive feedback based on deflectable elements of NED

[0163] o By using piezoresistive materials in deflectable elements for piezoresistive feedback

[0164] Overvoltage protection device based on MEMS device

[0165] o A beam structure arranged in the cavity (designed to accommodate opening and closing pressures).

[0166] o moves within the plane between the bottom sheet layer and the top sheet layer

[0167] o is triggered at a pressure of less than 5000 Pa, preferably less than 2000 Pa, particularly preferably less than 1,500 Pa, wherein the possible upper limit threshold is atmospheric pressure.

[0168] Close when pressure is below the shut-off pressure.

[0169] o becomes passive through the sudden jump function.

[0170] Two low-stress states can be adopted, depending on the pressure conditions in the cavity.

[0171] • State 1: Once the pressure drops below the shut-off pressure, the acoustic transducer cavity is shut off relative to the environment.

[0172] • State 2: Once the opening pressure is exceeded, the acoustic transducer cavity is connected to the environment.

[0173] It only requires moving a very small mass a very small distance.

[0174] Although some aspects have been described in the context of the apparatus, it should be understood that these aspects also represent the specification of the corresponding method, such that blocks or components of the apparatus should also be understood as corresponding method steps or features of method steps. Similarly, aspects described in conjunction with method steps or as method steps also constitute the specification of the corresponding blocks, details, or features of the corresponding apparatus.

[0175] The above embodiments are merely illustrative of the principles of this disclosure. It should be understood that modifications and variations of the arrangements and details described herein will be readily apparent to those skilled in the art. Therefore, this disclosure is intended to be limited only by the scope of the appended claims and not by the specific details presented herein through the explanation of the specification and embodiments.

Claims

1. A micromechanical structure, comprising: The first layer (12) includes a first opening (26) for allowing fluid (32) to pass through. A second layer (14) is arranged opposite to the first layer (12) and includes a second opening (28) for allowing the fluid (32) to pass through, and the second layer (14) together with the first layer (12) forms at least a portion of a layer stack having layers stacked in a stacking direction perpendicular to the substrate plane of the micromechanical structure; Cavity (18) is arranged between the first layer (12) and the second layer (14); Element (24), which is disposed in the cavity (18) and movable in a direction parallel to the plane of the substrate, the element (24) alternately includes at least a first positioning (381) and a second positioning (382), wherein, in the first positioning (381), the flow of the fluid (32) is blocked; and, in the second positioning (382), the fluid (32) is allowed to flow through the cavity (18) along the stacking direction. Wherein, the first opening (26) and the second opening (28) are arranged to be offset from each other when projected onto the substrate plane (x / y); wherein, the movable element (24) is configured to, when changing from the first position (381) to the second position (382), at least partially sweep across one of the first opening (26) and the second opening (28), and not sweep across the other of the first opening (26) and the second opening (28); or The micromechanical structure is configured to: change from the first position (381) to the second position (382) when a first pressure level (481) of the fluid (32) is applied at the first layer (12); and change from the second position (382) back to the first position (381) when a second pressure level (482) of the fluid (32) is applied at the first layer (12); wherein the first pressure level (481) is greater than the second pressure level (482).

2. The micromechanical structure according to claim 1, wherein the micromechanical structure is formed as an overpressure valve and configured to move the movable element (24) from the first position (381) to the second position (382) by means of overpressure at the first layer (12).

3. The micromechanical structure according to claim 1, wherein, A first fluid path (52) is arranged between the first opening (26) and the second opening (28) and is implemented to reduce the fluid pressure at the first layer (12) and to be blocked in the first positioning (381) of the movable element (24); wherein the micromechanical structure includes a second fluid path configured to reduce the fluid pressure at the second layer (14) by transporting the fluid (32) toward the first layer (12); wherein the movable element (24) or another element movable parallel to the plane of the substrate is configured to sometimes inhibit fluid flow through the second fluid path and sometimes allow fluid flow through the second fluid path.

4. The micromechanical structure according to claim 1, wherein, The movable element (24) is configured to subdivide the cavity (18) into at least a first sub-cavity (341) disposed on a first side (24A) of the movable element (24) and a second sub-cavity (342) disposed on a second side (24B) opposite to the first side (24A). The first sub-cavity (341) is fluidly coupled to the first opening (26), and the movable element (24) is configured to increase the volume of the first sub-cavity (341) when it changes from the first position (381) to the second position (382) until the first sub-cavity (341) is fluidly coupled to the second opening (28) and allows the fluid (32) to flow through.

5. The micromechanical structure according to claim 1, wherein, The movable element (24) includes a low stress state of mechanical stress in the first position (381) and is configured to include a high stress state in the second position (382) to change back from the second position (382) to the first position (381) while reducing mechanical stress.

6. The micromechanical structure according to claim 1, wherein, The movable element (24) is configured to receive a deformation force from the first pressure level for deforming the movable element (24) to the second position (382), wherein when transitioning to the second position (382), the material stress first increases and then decreases, wherein the movable element (24) is configured to take a steady state based on the decrease in material stress until it reaches or falls below the second pressure level (482) from the first pressure level (481).

7. The micromechanical structure according to claim 1, wherein, The movable element (24) is configured to change to the second position (382) based on the increase in pressure of the fluid (32) at the first layer (12), and remain in the second position (382) based on mechanical stress when the pressure decreases until the second pressure level is reached.

8. The micromechanical structure according to claim 1, wherein, The movable element (24) includes beam structures suspended on both sides, the beam structures bending in a first direction relative to an undeflected reference position; wherein the movable element (24) is configured to perform a deflection in a second direction relative to the reference position when changed to a second position (382).

9. The micromechanical structure according to claim 1, wherein, The movable element (24) is held at least at a first end at the cavity wall of the cavity (18) by a retaining element (441) associated with the first end; wherein the movable element (24) bends according to curvature in the first positioning (381) and is configured to first deform against the bending when changed to the second positioning (382); wherein the retaining element (441) is formed as a spring suspension of the movable element (24).

10. The micromechanical structure according to claim 9, wherein, The retaining element is a first retaining element (441), and the movable element (24) is held by a second retaining element (442, 84) at a second end (822) away from the first end.

11. The micromechanical structure according to claim 1, wherein the movable element (24) includes a first curved line parallel to the plane of the substrate in the first positioning (381), and includes a second curved line geometrically different from the first curved line in the second positioning (382).

12. The micromechanical structure according to claim 1, wherein, The movable element (24) includes a beam structure that can be bent parallel to the plane of the substrate, the beam structure having a locally weakened portion (66) of beam stiffness.

13. The micromechanical structure according to claim 1, wherein, In the first positioning (381), the movable element (24) includes a curved line projected onto the substrate plane, the algebraic sign of the radius of curvature (68) of the curved line having multiple continuous or discontinuous variations.

14. The micromechanical structure according to claim 1, wherein, The movable element (24) comprises a plurality of layers arranged adjacent to each other parallel to the plane of the substrate.

15. The micromechanical structure according to claim 1, comprising a mechanical element (74) extending from the cavity wall into the cavity (18) and configured to limit the deflection of the movable element (24) from the first positioning (381) by mechanical contact with the movable element (24).

16. The micromechanical structure according to claim 1, wherein, The movable element (24) is formed as an active element and is used to obtain drive signals (761-763), and is configured to: change the pressure sensitivity of the fluid (32) based on the drive signals (761-763) for changing from the first position (381) to the second position (382) and vice versa; and / or perform the change from the first position (381) to the second position (382) and vice versa based on the drive signals (761-763).

17. The micromechanical structure according to claim 1, wherein, The area size of the first opening (26) is different from the area size of the second opening (28); and / or The shape of the first opening (26) is different from the shape of the second opening (28).

18. The micromechanical structure according to claim 1, wherein, The movable element (24) is suspended on both sides, wherein the suspension is asymmetrical.

19. The micromechanical structure according to claim 1, wherein, The movable element (24) includes a sensor element configured to provide a sensor signal associated with the deflection state of the movable element (24).

20. The micromechanical structure according to claim 1, wherein, The movable element (24) is configured to alternately include the first positioning (381), the second positioning (382) and the third positioning (383), wherein the micromechanical structure is configured to allow a greater amount of fluid to flow through the cavity (18) in the third positioning (383) than in the second positioning (382).

21. A system comprising the micromechanical structure according to claim 1 (701, 702).

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