Micromechanical sensor assembly, method using a micromechanical sensor assembly

Abstract

The invention proposes a micromechanical sensor assembly, in particular an acceleration sensor, having a substrate with a main extension plane, wherein the sensor assembly comprises a first mass and a second mass, wherein the first and second masses are each at least partially movably configured in a perpendicular direction, i.e. perpendicular to the main extension plane of the substrate, wherein the first mass has a stop structure, characterized in that the stop structure has an overlap with the second mass in the perpendicular direction.

Description

Technical Field

[0001] This invention relates to a micromechanical sensor assembly and a method of using the micromechanical sensor assembly. Background Technology

[0002] Such micromechanical sensor assemblies, or microelectromechanical systems (MEMS), are generally known. They are manufactured, for example, in mass production for measuring acceleration and / or rotational speed for various applications in the automotive and consumer sectors.

[0003] As capacitive accelerometers with a detection direction perpendicular to the wafer plane (often referred to as the z-direction), they utilize, for example, a so-called "pendulum" or pendulum structure. The sensor principle of these pendulums is based on a spring-mass system, in its simplest form, in which a movable, asymmetric vibrating mass and two paired electrodes constitute two parallel-plate capacitors with capacitances C1 and C2. The vibrating mass is connected to a base via at least one torsion spring (usually more often two torsion springs). Because the mass structure is of different sizes on both sides of the torsion spring, the mass structure rotates relative to the torsion spring, which serves as the axis of rotation, when z-acceleration is applied. Therefore, the electrode spacing becomes smaller on the side with the larger mass and larger on the other side. The resulting capacitance change (which is typically evaluated differentially as C1-C2) is a measure of the applied acceleration. Such accelerometers are illustrated, for example, in EP 0 244 581 and EP 0 773 443B1.

[0004] A key trend in the development of micromechanical sensors is improving mechanical robustness, or overload resistance. Innovative applications have led to new mounting locations and consequently, new load profiles demanding increased robustness from the sensors. For example, consider inertial sensors mounted in the input pens of tablets, smartphones, or computers. While tablets or smartphones may only occasionally experience hard impacts, it must be considered that such impacts are very common in input pens.

[0005] Furthermore, to reduce manufacturing costs, accelerometers must be constructed as small as possible to accommodate as many chips as possible on a wafer. Reducing the sensor chip area necessitates decreasing the sensor's mass and spring stiffness. However, this also leads to a decrease in the spring's restoring force when the sensor impacts a stop.

[0006] The combination of these two trends (i.e., increasing impact loads while pursuing miniaturization) leads to a significant increase in the risk of sticking, where the movable sensor mass remains attached to the mechanical stationary stop once the adhesion force in the stop exceeds the restoring force of the spring-mass system.

[0007] To reduce adhesion, a so-called anti-stick coating (ASC) is often used, which is applied to the surface of the sensor after it has been exposed. However, if the sensor frequently hits a stop, the ASC may be damaged, causing the sensor to eventually exhibit an increased tendency to stick.

[0008] Z-accelerometer sensors are known from the prior art. DE 10 2008 043 753 A1 shows a sensor with a federnd stop implemented in the same functional plane as the vibrating mass. EP 3 111 232B1 shows an assembly in which the stop can function not only in one direction but also on both sides, i.e., not only in the direction of the bottom electrode but also in the direction of the sensor housing. DE 10 2012 207 939 A1 shows a federnd stop formed by a second thin functional layer above or below a thicker functional layer.

[0009] Even though a spring-loaded stop, when properly sized, can effectively improve the restoring force, adhesion remains a significant challenge for the quality of sensors, especially z-accelerometers. Summary of the Invention

[0010] Therefore, the objective of this invention is to provide a micromechanical sensor assembly having improved overload strength, wherein, in particular, it is robust and effectively reduces the risk of adhesion.

[0011] This invention proposes a micromechanical sensor assembly, particularly an accelerometer, having a substrate with a main extending plane. The sensor assembly includes a first mass and a second mass, each of which is at least partially movably configured along a vertical direction, i.e., perpendicular to the main extending plane of the substrate. The first mass has a stop structure that overlaps with the second mass along the vertical direction. The micromechanical sensor assembly according to the invention offers advantages over the prior art, enabling advantageous robustness of the sensor to overload conditions. Advantageously, for example, it can reduce the risk of adhesion of the z-accelerometer sensor under dynamic loads (i.e., non-static acceleration).

[0012] Another advantage is that the implementation of the stop structure can preferably be carried out in existing MEMS manufacturing processes without new technical requirements, so that no or almost no additional costs are incurred in manufacturing.

[0013] Furthermore, it is advantageous that the design changes required on the sensor according to the invention are minimal, so that the static characteristics (offset, sensitivity) and dynamic characteristics (frequency, damping, ...) of the sensor are not significantly altered. This also allows for cost-effective integration into existing sensor configurations.

[0014] Furthermore, the stop structure according to the invention can be implemented compactly, resulting in only negligible additional space requirements. Accordingly, no or almost no additional cost is incurred, particularly in sensor assemblies comprising first and second vibratory masses (dual cores) and having corresponding performance.

[0015] According to the invention, the overlap (in the vertical direction) between the stop structure and the second mass can be formed such that when the first mass (including the stop structure) and the second mass block are orthogonally projected onto the main extension plane of the base, an overlap is formed between the second mass and the stop structure. The stop structure is correspondingly arranged (in a top view of the main extension plane) such that it overlaps or partially overlaps with the second mass.

[0016] According to the invention, it is particularly conceivable that the first and second masses are arranged side by side as a single core of a sensor (especially a z-accelerometer and, for example, in the form of a pendulum or a ramp). The first and second masses can move independently of each other within the normal measurement range, i.e., particularly without contact. Therefore, it is particularly conceivable that the first stop structure and the second mass are constructed without contact and spaced apart from each other in the stationary state of the sensor assembly.

[0017] The stop structure is preferably arranged such that, in the event of strong deflection, i.e., under overload conditions, the second mass can mechanically contact the stop structure overlapping the first mass, and / or the second mass can mechanically contact the stop structure overlapping the first mass after the overload conditions.

[0018] The following describes an advantageous configuration of the invention.

[0019] According to one embodiment of the invention, the overlap of the stop structure with the second mass in the vertical direction can be formed by the stop structure being arranged at least partially between the second mass and the base in the vertical direction. Correspondingly, the stop structure can extend into the region below the second mass, such that there is an overlap or partial overlap between the stop structure and the second mass in a top view. This can particularly advantageously prevent adhesion.

[0020] According to one embodiment of the invention, the second mass may have another stop structure, wherein the other stop structure has another overlap with the first mass in the vertical direction. This other overlap of the other stop structure with the first mass (in the vertical direction) can be formed such that when the first mass and the second mass (including the other stop structure) are orthogonally projected onto the main extension plane of the substrate, another overlap is formed between the first mass and the other stop structure. The other stop structure (viewed in a top view of the (main extension plane)) is correspondingly arranged such that it has another overlap or partial overlap with the first mass. The two single cores arranged side-by-side can accordingly move independently, i.e., without contact, within the normal measurement range. Here, the sensor is preferably constructed such that, in the event of a strong deflection (under overload), at least one single core (i.e., the first or second mass) can mechanically contact the overlapping stop (i.e., the stop structure or another stop structure) of the other single core. Accordingly, a particularly advantageous improvement in the adhesion robustness of the two single cores can be achieved.

[0021] Accordingly, according to one embodiment of the invention, sensor assemblies with other masses and corresponding stop structures can also be considered.

[0022] According to one embodiment of the invention, another stop structure is formed to overlap the first mass in the vertical direction in such a way that the other stop structure is at least partially arranged between the first mass and the base in the vertical direction. The other stop structure may correspondingly extend into the region below the first mass, such that in a top view, there is another overlap or partial overlap between the other stop structure and the first mass.

[0023] According to one embodiment of the invention, the sensor assembly is configured such that contact is generated between the stop structure and the second mass in the event of an overload of the sensor assembly. Preferably, the sensor assembly is configured such that contact is generated between another stop structure and the first mass in the event of an overload of the sensor assembly. Therefore, an advantageous improvement in adhesion robustness for one or both masses can be achieved.

[0024] According to one embodiment of the invention, the stop structure is spring-loaded, wherein the other stop structure is preferably spring-loaded. The stop structure is spring-loaded in particular relative to a first mass, or spring-loaded onto the first mass. The other stop structure is spring-loaded in particular relative to a second mass, or spring-loaded onto the second mass. This advantageously reduces the probability of adhesion. Furthermore, in an advantageous manner, even in a particularly thin embodiment of the corresponding stop structure, damage to the spring-loaded stop structure can be ensured upon collision with the corresponding other sensor core.

[0025] According to one embodiment of the invention, the second mass has contact elements, particularly protrusions, wherein the contact elements are arranged such that, in the event of an overload of the sensor assembly and / or after an overload, contact between the first and second masses is generated by the contact elements and a stop structure. Preferably, the first mass has another contact element, particularly another protrusion, wherein said other contact element is arranged such that, in the event of an overload of the sensor assembly and / or after an overload, contact between the first and second masses is generated by another contact element and another stop structure. Thus, the contact elements can be constructed, for example, as protrusions, arches, or agglomerates on the underside of the second mass, and are arranged above the stop structure of the first mass (and do not contact and are spaced apart from the stop structure of the first mass in the static state). Corresponding arrangements can be considered for another contact element and another stop structure for the first mass. Thus, each contact area can be adjusted with particular precision by the geometry of each stop structure and the geometry of the corresponding contact element.

[0026] According to one embodiment of the invention, it is preferable that the stop structure is constructed as a single piece with or as part of the first mass. Preferably, it is preferable that the other stop structure is constructed as a single piece with or as part of the second mass. This results in a particularly low-cost and efficient manufacturing process. However, alternatively, it is also possible that the stop structure is a separate structure connected to the first mass, and / or the other stop structure is a separate structure connected to the second mass.

[0027] Another subject of the present invention is a method for measuring parameters using a micromechanical sensor assembly according to an embodiment of the invention, particularly a method for measuring acceleration using an accelerometer.

[0028] According to one embodiment of the invention, it is conceivable that, in the event of an overload of the sensor assembly, contact is formed between the stop structure and the second mass, wherein preferably, in the event of an overload of the sensor, contact is formed between another stop structure and the first mass. Alternatively or additionally, it is conceivable that, in the event of an overload of the sensor assembly, contact is formed between the stop structure and the second mass, wherein preferably, in the event of an overload of the sensor assembly, contact is formed between the other stop structure and the first mass.

[0029] According to one embodiment of the invention, in the event of an overload of the sensor assembly, contact is formed between the stop structure and the second mass before the second mass and / or the first mass comes into contact with another structure of the sensor assembly. Preferably, in the event of an overload of the sensor assembly, contact is formed between the other stop structure and the first mass before the first mass and / or the second mass comes into contact with another structure of the sensor assembly. Accordingly, the first mass and the second mass can move freely until contact with the corresponding stop structure of the other mass is made. Therefore, it is particularly advantageous to consider, in the event of an overload, that the first contact between one of the masses and the stop structure of the corresponding other mass is made before contact with the stop of the substrate or with the stop of any other structure.

[0030] The advantages and configurations described in conjunction with the micromechanical sensor assembly or embodiments of the micromechanical sensor assembly according to the present invention can be applied to the methods for using micromechanical sensor assemblies. Attached Figure Description

[0031] Embodiments of the invention are shown in the accompanying drawings and described in detail in the following description.

[0032] Figures 1, 2, 3, and 4 show schematic diagrams of sensors according to the prior art.

[0033] Figure 5 shows a schematic diagram of the dual-core assembly used to illustrate the present invention.

[0034] Figure 6 shows a schematic diagram of a sensor assembly according to one embodiment of the present invention.

[0035] Figure 7 shows a schematic diagram of a sensor assembly according to one embodiment of the present invention.

[0036] Figure 8 A schematic diagram of a sensor assembly according to one embodiment of the present invention is shown.

[0037] In different accompanying drawings, the same parts are given the same reference numerals and are therefore usually named or mentioned only once each. Detailed Implementation

[0038] Figure 1 shows the components of a capacitive accelerometer according to the prior art, which has a detection direction along the vertical direction 110 (z-direction) and perpendicular to the main extension plane 100 of the substrate 2. The sensor configuration according to Figure 1 is a "pendulum structure" or "pendulum". The sensor principle of these pendulums is based on a spring-mass system, in which, in the simplest case, a movable asymmetric vibrating mass 40 (which is implemented in functional layer P3 in Figure 1) forms two parallel plate capacitors with capacitances C1 and C2 with two analytical evaluation electrodes 41, 42 (which are implemented in layer P1) fixed on the substrate at a distance d0. The vibrating mass 40 is connected to the base or substrate 2 via a suspension device 46 through at least one torsion spring 45 (usually more often two torsion springs for symmetry reasons). Because the mass structures on both sides of the torsion spring 45 are of different sizes, the mass structures rotate relative to the torsion spring 45, which is the axis of rotation, under the action of z-acceleration. Therefore, the spacing between electrodes 41 and 42 is analyzed and evaluated to be smaller on the side with a larger mass proportion and larger on the other side. The resulting capacitance change (which is typically analyzed and evaluated differentially as C1-C2) is a measure of the acceleration of the action. Typically, movable structures and masses have perforations. However, perforations are omitted from all the following figures for clarity.

[0039] By increasing the impact load in various applications, while simultaneously pursuing miniaturization, the risk of adhesion is improved. Specifically, once the adhesion force in the stop exceeds the restoring force of the spring-mass system, the movable mass 40 remains suspended on the fixed stop of the machine. This stop can be fixed, spring-elastic, or a combination of a fixed stop and a spring-elastic stop.

[0040] Figure 2 Based on the structure shown in Figure 1, a simplified example of a fixed stop 49 is illustrated. This fixed stop is arranged in a granular form on the underside of the vibrating mass 40 and stops on the P1 layer when the pendulum deflects strongly. The stopping region 50 in the P1 layer has the same potential as the movable structure. This ensures that no electrical short circuit is generated, and furthermore, no large additional electrical force acts in the stopping region, which could additionally increase the sensor's impact velocity and thus the risk of adhesion. The sensor can remain adhered to the stop under adverse conditions, i.e., when the adhesion force F in the granular stop... a Greater than the restoring force F generated by one or more torsion springs 45 r At times, or alternatively, when the adhesion torque, i.e. F a *R a Greater than the reset torque M r =k t When *α, it is expressed through torque, where R aIndicates the distance between the stop particle 49 and the torsion axis, k t This represents the torsional stiffness of the spring, and α represents the deflection angle in the stop state. The deflection angle α can also be expressed by the fundamental pitch d0 and the particle spacing R relative to the torque axis. a Using α=d0 / R a Expression. To prevent sticking, the following condition must be met: k t d0 / R a >F a R a , or k t >F a R a 2 / d0.

[0041] This equation shows that, given an adhesion force F a Given a basic spacing d0, it is advantageous to place the stop cluster 49 as close as possible to the axis of torsion. On the one hand, this increases the rotation angle, and on the other hand, reduces the lever arm used for adhesion. Therefore, theoretically, the cluster spacing R... a A 2-fold reduction results in a 4-fold reduction in the required torsional stiffness. This is advantageous because a softer spring leads to higher mechanical and electrical sensitivity of the sensor, as well as better resistance to substrate bending. However, in practice, the stop joint 49 can only be pulled toward the torsion spring axis to such an extent that it still reliably prevents the rocker arm from stopping on the outer edge, since the stop joint 49 would otherwise be ineffective; not only the rocker arm's stopping surface but also the adhesion torque would increase significantly, greatly increasing the probability of adhesion.

[0042] In the combination of a spring-loaded stop and a fixed stop, when the vibrating mass deflects strongly, the spring-loaded stop engages first, before the movable mass hits the fixed stop. This reduces the risk of sticking because the spring-loaded stop deflects slightly and generates an additional restoring force. Furthermore, the deflection of the spring-loaded stop reduces pulse transmission through the vibrating mass, resulting in less damage to the stop surface. Therefore, wear on the ASC is reduced on the one hand, and very fine particles that may form during frequent stopping are also reduced in this way. Figure 3 A slightly modified, but equally meaningful, diagram is shown according to DE 10 2012 207 939 A1. Figure 3 The components. Spring-elastic stops 61, 62 are implemented in plane P2 and function in the direction of fixed electrodes 41, 42 (bottom electrodes) formed in plane P1, wherein the stop points 51, 52 (of layer P1) are also held without potential relative to the movable mass 40.

[0043] Even though spring-loaded stops, when properly sized, can effectively improve the restoring force, adhesion remains a significant challenge for the quality of MEMS, especially accelerometers, and specifically z-accelerometers.

[0044] The two micromechanical layers P2 and P3 used for movable structures or masses can not only be used to implement the spring-loaded stop of the z-accelerometer, but also primarily to improve its performance. This is particularly evident in DE 10 2009 000 167 A1. Figure 8 The corresponding solution is described in [the document / document]. Figure 4 This scheme is illustrated in a slightly modified form. First fixed electrodes 41 are electrically connected to each other, and second fixed electrodes 42 are electrically connected to each other. For example, the first fixed electrode 41 corresponds to capacitor C1, while the second fixed electrode 42 corresponds to capacitor C2. Differential signals C1-C2 are evaluated by electrical analysis. In particular, these top electrodes can be suspended by a central suspension device 48. The mass 40 can be suspended by a central suspension device 46 and rotated about a torsion axis 47. This z-sensor demonstrates advantages over a pendulum structure consisting only of a silicon functional layer P3 and a wiring layer P1. In particular, an increased capacitance density (i.e., capacitance / area) can be achieved due to the use of both the bottom electrode (layer P1) and the top electrode (layer P3). Therefore, an improved signal-to-noise ratio (or a reduced sensor area without changing noise performance) and lower sensitivity to bending stress can be achieved with the same sensor area, because the top electrode is centrally suspended and the bottom electrode (due to the additional capacitance formed by the top electrode) can be implemented more compactly. Both aspects result in smaller offset and sensitivity drift when bending stress occurs (e.g., due to circuit board bending or thermomechanical stress).

[0045] When two such z-sensor cores A and B are arranged side-by-side, further performance improvements in noise and offset can be achieved. The sensor cores can be arranged to move parallel to each other or rotate 180° (and naturally, additionally, move laterally). The electrical signals are then jointly analyzed and evaluated as C_A1 + C_B1 - C_A2 - C_B2. To illustrate the invention, in Figure 5aPossible components of this dual-pendulum configuration are shown in the top view of layer P3 in sections (b), (c), and (d), respectively. The advantage of the dual-pendulum configuration is that it doubles the electrical sensitivity of the sensor. Furthermore, the statistical averaging of the two sensor cores also reduces Brownian noise (caused by statistical collisions between the vibrating mass and gas particles in the sensor cavity) by a factor of √2 to 1.41. These two effects lead to an improved signal-to-noise ratio. Another advantage of the dual-pendulum configuration is that it significantly reduces sensitivity to mechanical stresses, which cause bending of the sensor substrate and thus undesirable spacing and capacitance changes on the analytical evaluation electrodes, because the capacitance changes on the analytical evaluation electrodes can be fully or at least partially compensated, depending on the deformation zone in the cleverly designed core assembly. This leads to improved offset stability. For this purpose, for example, when the sensor cores are arranged with their rotations 180° relative to each other (… Figure 5b The components are suitable. Furthermore, the parasitic pendulum deflection can also be compensated for by a clever arrangement of the two cores, the parasitic pendulum offset caused by the lateral temperature gradient in the chip and resulting in an offset signal in the case of a single pendulum. Therefore, when the two sensor cores are arranged rotated 180° relative to each other ( Figure 5b )) components are especially suitable.

[0046] Figure 6 shows a schematic diagram of a sensor assembly 1 according to an embodiment of the present invention. The sensor assembly 1 is, in particular, a z-accelerometer, i.e., an accelerometer for sensing acceleration along a vertical direction 110, perpendicular to the main extension plane 100 of the base 2 of the sensor assembly 1. The sensor assembly 1 includes a first mass 10 and a second mass 20, the first and second masses being respectively configured as pendulum structures and thus at least partially movable along the vertical direction 110, perpendicular to the main extension plane 100 of the base 2. Here, the first mass 10 is suspended by a torsion spring 45' and a suspension device 46'. The second mass is suspended by another torsion spring 45' and another suspension device 46'. The first mass 10 includes a stop structure 11 and the second mass 20 includes a stop structure 21. The stop structure 11 overlaps with the second mass 20 along the vertical direction 110. The other stop structure 21 overlaps with the first mass 10 along the vertical direction 110. The two sensor cores or masses 10, 20 rotate 180° relative to each other, as shown in... Figure 5b The situation with the sensor shown.

[0047] remove Figure 5b )external Figure 6a The diagram also shows a rocker arm or a movable structure with masses 10 and 20 implemented in the plane of P2. Conversely, in Figure 6bFor clarity, only the regions of the movable masses 10, 20 implemented in layer P2 are shown. Stop structures 11, 21 are preferably constructed as part of masses 10 or 20 and are highlighted only for illustration purposes. Stop structure 11 is attached to the first sensor core or the first mass 10 at attachments 12', 12"". The free ends (or multiple free ends) of stop structure 11 extend into the region of the adjacent sensor core of the second mass 20. In the illustrated embodiment, stop structure 11 comprises two spring-loaded beams 11', 11" or stop springs 11', 11" wherein, in the top view, one beam 11', 11" is arranged above and below the torsion spring axis of torsion spring 45'. Figure 6a The other stop structure 21 is attached to the second sensor core or the second mass 10 at attachment portions 22', 22"). The free ends (or multiple free ends) of the other stop structure 21 extend into the region of the adjacent sensor core of the first mass 10. In the illustrated embodiment, the other stop structure 21 includes two spring-elastic beams 21', 21" or stop springs 21', 21" wherein each beam 21', 21" is arranged above and below the torsion spring axis of the other torsion spring 45'. Figure 6a )).

[0048] Zi Fu Figure 6c ) and 6d) show two cross sections. Here, Figure 6c ) shows along Figure 6a The cross section of CD and Figure 6d ) shows along Figure 6a The cross section of EF.

[0049] The base 2 and plane P1 of the sensor are not shown for illustration purposes. Accordingly, only layers P2 and P3 are shown.

[0050] exist Figure 6c As shown in the diagram, another stop structure 21 (or a stop spring 21' of another stop structure 21) attached to the second mass 20 extends into the region of the first mass 10 or the first sensor core. Here, the other stop structure 21 is partially arranged between the first mass 10 and the base 2 (not shown) along the vertical direction 110. Thus, another overlap is formed between the other stop structure 21 and the first mass 10 along the vertical direction 110. Accordingly, an overlap region 15 between the other stop structure 21 and the first mass 10 is shown in the top view of the main extension plane 100. Through the overlap region 15, contact occurs between the first mass 10 and the stop spring 21' of the second mass 20 during sufficiently large vertical relative movements (e.g., in the case of overload).

[0051] exist Figure 6dAs shown in the diagram, a stop structure 11 (or a stop spring 11' of the stop structure 11) attached to the first mass 10 extends into the region of the second mass 20 or the second sensor core. Here, the stop structure 11 is partially arranged between the second mass 20 and the base 2 (not shown) in the vertical direction 110. Therefore, an overlap between the stop structure 11 and the second mass 20 is formed in the vertical direction. Accordingly, an overlap region 14 between the stop structure 11 and the second mass 20 is shown in the top view of the main extending plane 100. Through the overlap region 14, contact between the second mass 20 and the stop spring 11' of the first mass 10 occurs during a sufficiently large vertical relative movement in the opposite direction.

[0052] By arranging the masses 10 and 20 as shown in Figure 6, which are rotated 180° relative to each other, the two pendulums or masses 10 and 20 will move in opposite phase under z-acceleration. The stop springs 11', 11" and 21', 21" are positioned such that no contact occurs between the two masses 10 and 20 on the stop springs 11', 11" and 21', 21" within the normal measurement range (small signal range) of the sensor. Therefore, the masses 10 and 20 move completely independently of each other. Conversely, under overload, i.e., at large z-accelerations far from the measurement range, contact occurs between the two masses 10 and 20 on at least one stop spring 11', 11" and 21', 21" specifically shortly before the pendulum ends of the masses 10 and 20, or possibly additionally present stop nodes, contact the plane P1. By means of the stop structures 11, 21 according to the invention (in this embodiment by means of stop springs 11', 11" , 21', 21" ), in contact, the restoring torque of the two rocker arms or the torsion springs 45', 45" of masses 10, 20 acts advantageously. Because these rocker arms move relative to each other, i.e., the relative angular deflection is twice the angular deflection of each individual rocker arm, the torsion axis (R) is... a The stop spacing can be chosen to be significantly smaller than in the case of a standard rocker arm. As already shown, reducing the stop spacing relative to the torsional axis can decisively help reduce the risk of sticking.

[0053] In summary, this allows for a significant improvement in robustness against overload, especially against repetitive overload.

[0054] By arranging at least one stop spring 11', 11" , 21' , 21" in each sensor core (the stop springs extend into adjacent cores respectively), the following advantages can also be achieved: contact between the two sensors can be made in the case of overload in the +z and -z directions (i.e., not only overload in the vertical direction 110 but also overload in the direction opposite to the vertical direction 110).

[0055] In the embodiment shown in Figure 6, each mass 10, 20 has two overlapping stop springs 11', 11"', 21', 21"', one above and one below the torsion spring axis (in the top view). However, alternatively, the stop structures 11, 21 of the mass blocks 10, 20 may be constructed such that they each have only one stop spring 11', 21'. Alternatively, additional stop springs or other geometries of the stop structures 11, 21 may be considered. For example, rigid, non-spring-elastic stop structures 11, 21 may also be considered alternatively or additionally.

[0056] Figure 7 shows a schematic diagram of a sensor assembly 1 according to another embodiment of the present invention. The assembly according to Figure 7... Figure 5d Starting from the basic components of the first mass 20. In this case, the masses 10, 20 or the pendulum also rotate 180° relative to each other, but in this embodiment, they are now moved laterally perpendicular to the axis of the torsion springs 45', 45" so that the heavier pendulum sides of the masses 10, 20 are directly opposite each other. In this case, overlapping stop structures 11, 21, especially stop springs 11', 11" , 21', 21" are also realized. However, this function is different from the function in the embodiment shown in FIG. 6. The first mass 10 includes in particular a stop structure 11 having two stop springs 11', 11" which (in the top view of the main extension plane 100 of the base 2) respectively have overlap with the second mass 20. The second mass 20 includes another stop structure 21 having two additional stop springs 21', 21" which (in the top view) respectively have overlap with the first mass 10. Figure 7a For clear reasons, Figure 7b The top view shows only the areas where the movable mass blocks 10 and 20 are implemented in layer P2. Figure 7c )and Figure 7d The figures along section GH( Figure 7c )) and IJ( Figure 7d The cross-section of )).

[0057] In the embodiment according to Figure 7, when z-acceleration occurs, the two oscillating masses 10 and 20 move in phase. Therefore, theoretically, even under overload conditions, the two masses 10 and 20 will not move relative to each other and thus will not come into contact. The two masses 10 and 20 may have their own additional stops or their own additional stop clusters and / or spring-elastic stops (not shown) known according to the prior art within their respective sensor cores. If one of the sensor cores or one of the masses 10 and 20 becomes stuck at one of these stops, the other sensor core will also enter a stuck state with a very low probability, because sticking is a phenomenon with a strong statistical component. Therefore, the non-sticky masses 10 and 20 will swing back to their rest positions after the overload condition. Here, depending on the dimensional design of the overlapping stop springs 11', 11" , 21' , 21" , the two masses 10 , 20 will contact one or more stop springs 11', 11" , 21' , 21" , such that the torsion springs 45' , 45" of the non-adhering masses 10 , 20 provide additional restoring force to the adhered masses 10 , 20 and thus there is a probability of increased movement, allowing the adhered masses 10 , 20 to move freely again. Even if the dimensional design of the overlapping stop springs 11', 11" , 21' , 21" is such that no contact occurs when the body swings back to the stationary position. The contact between masses 10 and 20 allows the non-adhesive masses 10 and 20 to deflect in the opposite direction under subsequent overload conditions. At the latest, contact between masses 10 and 20 occurs on one or more overlapping stop springs 11', 11"', 21'', 21"'. Therefore, in a subsequent impact, the non-adhesive masses 10 and 20 can be separated from the adhering masses 10 and 20 again and de-adhesive through a brief but very strong pulse transmission. In this case, the component is therefore rarely used to prevent the individual lever from sticking, but rather to separate or de-adhere after sticking has occurred.

[0058] In the assemblies of Figures 6 and 7, the masses 10 and 20 are hardly altered by the overlapping stop springs 11', 11" and 21' and 21" such that they do not significantly affect the static characteristics (offset, sensitivity) and dynamic characteristics (frequency, damping) of the sensor. Therefore, the overlapping stop springs 11', 11" and 21' and 21" only have the described beneficial effect on the robustness of the sensor under overload conditions and hardly affect the free vibration characteristics.

[0059] In the embodiments of Figures 6 and 7, masses 10 and 20 are respectively constructed as pendulums. However, according to the invention, masses 10 and 20 may alternatively have other configurations. According to an embodiment of the invention, stop structures 11 and 21 can be used not only for z-pendulums but also, for example, for trampolinartig z-accelerometers implemented as dual-cores. In such an embodiment, masses 10 and 20 are constructed, for example, in a trampolinartig configuration. The trampolinartig z-accelerometer performs a pure translational z-motion along the vertical direction 110. In a simple example, in a dual-core assembly, the two single-core trampolinartig masses 10 and 20 move in phase, such that the stop structures 11 and 21 (e.g., including overlapping stop springs 11', 11", 21', 21") function as according to Figure 7. In this case, contact on the stop structures 11 and 21 typically occurs only after one of the masses 10 and 20 has come into contact with a stop within its own sensor core surface and may have entered an adhesive state. The still movable masses 10 and 20 can then be separated from the adhered masses 10 and 20 again, especially in subsequent vibration situations.

[0060] In the embodiments according to Figures 6 and 7, the stop structures 11 and 21 are respectively constructed in layer P2. However, alternatively, it is also conceivable that the stop structures 11 and 21 are implemented in layer P3, or partially in layer P2 and partially in layer P3.

[0061] In the embodiments according to Figures 6 and 7, the stop structures 11 and 21 respectively include stop springs 11', 11" and 21', 21"". However, alternatively, it can be considered that the stop structures 11 and 21 are implemented very rigidly or stiffly, i.e., non-spring-elastically. However, mechanical robustness should be noted here. Otherwise, especially in the relatively thin layer P2, the overlapping stop structures 11 and 21 may detach from the rigid P3 structure under high overload conditions.

[0062] As shown in the embodiment according to Figures 6 and 7, there is no contact element 70, in particular a protrusion or stop agglomerate, on the underside of masses 10 and 20 in the contact area with the stop structures 11 and 21 in layer P3. However, it is conceivable that such an additional contact element 70 is implemented on the underside of masses 10 and 20. For this purpose, it can be implemented, for example, in machining (additional plane). With the aid of this additional contact element 70, the contact surface in the stop can be very small and well-defined. Corresponding components are exemplarily shown in... Figure 8 (Based on) Figure 7dThe components are shown. Here, another contact element 70 is arranged on the first mass 10. In the event of or after an overload of the sensor assembly, contact is established between the first mass 10 and the second mass 20 via the other contact element 70 and the other stop structure 21. Alternatively or additionally, a contact element may be arranged on the second mass 20 that contacts the stop structure 11 (not shown) in or after an overload.

Claims

1. A micromechanical sensor assembly (1) having a substrate (2) with a main extending plane (100), wherein, The sensor assembly (1) includes a first mass (10) and a second mass (20), wherein the first mass and the second mass (10, 20) are respectively at least partially movably constructed along a vertical direction (110) perpendicular to the main extension plane (100) of the substrate (2). The first mass (10) includes a stop structure (11) having two stop springs, each of which overlaps with the second mass (20) along the vertical direction (110). The second mass (20) includes another stop structure (21) having two additional stop springs, each of which overlaps with the first mass (10) along the vertical direction (110). The first mass (10) is configured such that it makes another overlapping mechanical contact with the other stop structure (21) along the vertical direction (110), and the second mass (20) is configured such that it makes the overlapping mechanical contact with the stop structure (11) along the vertical direction (110).

2. The micromechanical sensor assembly (1) according to claim 1, characterized in that, The overlap of the stop structure (11) and the second mass (20) along the vertical direction (110) is formed by the stop structure (11) being arranged at least partially between the second mass (20) and the base (2) along the vertical direction (110).

3. The micromechanical sensor assembly (1) according to claim 1, characterized in that, The other stop structure (21) is formed by another overlap of the first mass (10) along the vertical direction (110) in such a way that the other stop structure (21) is arranged at least partially between the first mass (10) and the base (2) along the vertical direction (110).

4. The micromechanical sensor assembly (1) according to any one of claims 1 to 3, characterized in that, The sensor assembly (1) is configured such that, under overload conditions, contact is formed between the stop structure (11) and the second mass (20).

5. The micromechanical sensor assembly (1) according to any one of claims 1 to 3, characterized in that, The stop structure (11) is spring-elastically constructed.

6. The micromechanical sensor assembly (1) according to any one of claims 1 to 3, characterized in that, The second mass (20) has a contact element, wherein the contact element is arranged such that, in the event of an overload of the sensor assembly (1) and / or after an overload, contact is generated between the first mass (10) and the second mass (20) through the contact element and the stop structure (11).

7. The micromechanical sensor assembly (1) according to claim 1, characterized in that, The sensor assembly (1) is configured as an acceleration sensor.

8. The micromechanical sensor assembly (1) according to claim 4, characterized in that, The sensor assembly (1) is configured such that, under overload conditions, contact is formed between the other stop structure (21) and the first mass (10).

9. The micromechanical sensor assembly (1) according to claim 5, characterized in that, The other stop structure (21) is spring-elastically constructed.

10. The micromechanical sensor assembly (1) according to claim 6, characterized in that, The first mass (10) has another contact element (70), wherein the other contact element (70) is arranged such that, in the event of overload of the sensor assembly (1) and / or after the event of overload, contact is generated between the first mass (10) and the second mass (20) through the other contact element (70) and the other stop structure (21).

11. The micromechanical sensor assembly (1) according to claim 10, characterized in that, The contact element is a protrusion, and the other contact element (70) is another protrusion.

12. A method for measuring a measurement parameter using a micromechanical sensor assembly (1) according to any one of claims 1 to 11.

13. The method according to claim 12, characterized in that, In the event of an overload of the sensor assembly (1), contact is formed between the stop structure (11) and the second mass (20).

14. The method according to claim 13, characterized in that, In the event of an overload of the sensor assembly (1), contact is formed between the other stop structure (21) and the first mass (10).

15. The method according to any one of claims 12 to 14, characterized in that, In the event of overload of the sensor assembly (1), contact is formed between the stop structure (11) and the second mass (20) before the second mass (20) and / or the first mass (10) come into contact with another structure of the sensor assembly (1).

16. The method according to claim 15, characterized in that, In the event of overload of the sensor assembly (1), contact is formed between the other stop structure (21) and the first mass (10) before the first mass (10) and / or the second mass (20) come into contact with another structure of the sensor assembly (1).

17. The method according to claim 12, characterized in that, The method is configured to use an accelerometer to measure acceleration.

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