Early impact out-of-plane motion limiter for microelectromechanical devices

Abstract

The present disclosure relates to early collision out-of-plane motion limiters for microelectromechanical devices. A microelectromechanical device includes a movable rotor and a fixed stator located in a device plane and a motion limiter that prevents the movable rotor from coming into contact with a fixed wall in a vertical direction perpendicular to the device plane. The motion limiter extends between the rotor and the stator and includes a stopper bar that is rotatable out of the device plane.

Description

Technical Field

[0001] This disclosure relates to microelectromechanical (MEMS) devices, and more particularly to motion limiters that prevent undesirable contact between movable device portions and fixed device portions. Background Technology

[0002] Microelectromechanical (MEMS) devices, such as accelerometers and gyroscopes, typically include a mass element suspended from fixed anchors by a flexible suspension structure that allows the mass element to move relative to an adjacent fixed structure. The movable mass element may be referred to as a rotor, and the fixed portion with the anchors positioned may be referred to as a stator. The fixed structure adjacent to the rotor typically also includes walls that form an enclosure around the rotor and other moving parts of the MEMS device.

[0003] Direct physical contact between the rotor and the stationary structure is generally undesirable because it can disrupt the operation of the device. Although the rotor and its suspension structure can be sized to prevent direct contact from occurring during normal operation, abnormal external vibrations can still cause the rotor to shift and come into direct contact with the stationary structure, resulting in structural damage, static friction, electrical short circuits, or other malfunctions.

[0004] Motion limiters can be implemented in MEMS devices to reduce or prevent these harmful consequences. The motion limiter may, for example, include a protrusion attached to the rotor and extending from the rotor toward an adjacent stationary structure. The gap between the motion limiter protrusion and the stationary structure can be narrow in the desired direction of motion, such that the protrusion will be the first part to contact the stationary structure in the event of external vibration. Damage can be reduced, for example, by placing the motion limiter protrusion as far as possible from the most sensitive area of ​​the rotor.

[0005] However, the space available for motion limiters is often limited by cost and design considerations. Furthermore, a common problem with rigidly fixing motion limiter bumps to the rotor is that the bumps and rotor typically move together. If the collision between the bump and the stationary structure is violent, particles can be released from the stationary structure or from the bump itself. These particles can move toward more sensitive areas of the device, restrict dynamic operating range, and cause short circuits or other damage. Summary of the Invention

[0006] The purpose of this disclosure is to provide an apparatus that alleviates the aforementioned problems. This purpose is achieved by an apparatus characterized by the features stated in the independent claim. Preferred embodiments of this disclosure are disclosed in the dependent claims.

[0007] This disclosure is based on the concept of constructing a motion limiter that is connected to a rotor and initiates motion through the rotor's out-of-plane movement. The motion limiter moves toward the stationary structure faster than toward the rotor, allowing contact to occur in the early stages of motion before the rotor has acquired significant momentum. One advantage of this device is that the collision between the motion limiter and the stationary structure will be gentle. Attached Figure Description

[0008] The present disclosure will now be described in more detail with reference to the accompanying drawings, in which:

[0009] Figures 1a to 1c The illustration shows a first device portion, a second device portion, and a motion limiter extending between the first device portion and the second device portion.

[0010] Figures 2a to 2e The diagram illustrates the operation of the motion limiter when the first part of the device is a rotor.

[0011] Figures 3a to 3c The diagram illustrates the operation of the motion limiter when the second part of the device is a rotor. Detailed Implementation

[0012] The rotor in a MEMS device is typically formed in a device layer, for example, by etching the device layer. The device layer can be, for example, a silicon wafer. Alternatively, the device layer can be a silicon layer already deposited on a substrate. During device fabrication, the rotor is partially released from the surrounding mounting structure. The rotor can be suspended from fixed anchor points, for example, by a flexible suspension member. The suspension member can be formed in the same etching process as the rotor, and the area of ​​the mounting structure where the anchor points are located can be a region of the device layer adjacent to the rotor.

[0013] In a MEMS device, the stator adjacent to the rotor can be any part of the device layer that remains fixed to a given position (different from the rotor) relative to the surrounding fixed structure regardless of the motion of the device. In measurements that track rotor motion, such as in capacitance measurement devices where a set of electrodes is fabricated on the stator and a set of adjacent auxiliary electrodes is fabricated on the rotor, the stator can serve as a fixed reference point. Piezoelectric measurement devices can alternatively be fabricated on flexible suspensions extending from the stator to the rotor. However, the fixed stator used for constructing the motion limiter described in this disclosure does not necessarily have to be the same structure used for measuring rotor motion. Two separate stator structures can be used instead for both purposes.

[0014] The device layer defines a device plane, which is illustrated in this disclosure as an xy-plane. The device plane may also be referred to as a horizontal plane. A direction perpendicular to the device plane is illustrated in this disclosure using the z-axis, and this direction may be referred to as a vertical direction or an out-of-plane direction. The terms "horizontal" and "vertical" in this disclosure refer only to the plane and the direction perpendicular to that plane. In the manufacture or use of the device, the terms "horizontal" and "vertical" do not imply any meaning regarding how the device should be oriented relative to the Earth's gravitational field. This also applies to terms related to "vertical," such as "above" and "below," "high" and "low," "up" and "down."

[0015] In some technical applications, the rotor can be designed to undergo linear out-of-plane motion, wherein the entire rotor moves out of the device plane. In other applications, the rotor can be designed to undergo rotational out-of-plane motion, wherein the rotor rotates about an axis located in the device plane. This disclosure provides motion limiters intended to restrict any type of out-of-plane motion.

[0016] This disclosure describes a microelectromechanical device (MEMS) including a movable rotor and a fixed stator, the movable rotor being positioned in a stationary position in a horizontal device plane, and the fixed stator being positioned adjacent to the movable rotor in the same horizontal device plane. The device also includes a fixed wall defining a wall plane adjacent to the horizontal device plane, wherein the fixed wall is separated from the movable rotor in a vertical direction by a rotor-wall gap, wherein the vertical direction is perpendicular to the horizontal device plane.

[0017] The device also includes a motion limiter and a platform structure. The motion limiter includes a stop element. The platform structure is adjacent to and vertically separated from the horizontal device plane. When the movable rotor is in the horizontal device plane, the stop element and the platform structure are separated by a vertical stop gap. As the movable rotor undergoes vertical movement toward the fixed wall, the device causes the stop element to contact the platform structure across the stop gap before the movable rotor contacts the fixed wall across the rotor-wall gap.

[0018] The movable rotor is a first device part and the fixed stator is a second device part, or the movable rotor is a second device part and the fixed stator is a first device part.

[0019] The edges of the first and second device portions are separated in a horizontal device plane by a rotor-stator gap extending laterally. A motion limiter extends across the rotor-stator gap from the first to the second device portion, and the motion limiter includes a torsionally flexible first attachment segment attached to the edge of the first device portion and extending laterally toward the second device portion. The motion limiter also includes a stop bar attached to the attachment segment.

[0020] The first side of the stop bar extends from the attachment section along a first lateral direction. The second side of the stop bar extends from the attachment section along a second lateral direction. The second lateral direction is opposite to the first lateral direction. The stop bar includes a stop element located on its second side. The motion limiter also includes a torsionally flexible connecting section that extends from the edge of the second device portion to the first side of the stop bar.

[0021] In some applications, the movable rotor may be referred to as a mass element, a sensing mass, or a Coriolis mass. When the rotor is not undergoing motion relative to a stationary structure, it is in its rest position. The rotor can be moved away from its rest position by a force transducer and can be driven, for example, into a oscillating motion. In addition to (or alternatively) such intentional actuation, the rotor can be moved away from its rest position by an external force acting on the MEMS device. The motion limiter described in this disclosure can be configured to limit any type of out-of-plane motion.

[0022] The device section referred to as the "first device section" can be a movable rotor or a fixed stator. The device section referred to as the "second device section" is the other of these two sections. Depending on which of these options applies, the platform structure can be (a) a structure of the fixed wall itself or attached to the fixed wall, or (b) a structure located on the opposite side of the device plane compared to the fixed wall. These options will be explained in more detail below with reference to the accompanying drawings.

[0023] Figure 1a The diagram illustrates a first device portion 11 and a second device portion 12. Here, the lateral direction is the y-direction. The edge 111 of the first device portion 11 and the edge 121 of the second device portion are separated by a rotor-stator gap 181. The motion limiter extends laterally across... Figure 1a The structure of this gap in the middle.

[0024] The motion limiter includes a torsionalally flexible attachment segment 14. In other words, the attachment segment 14 can be twisted about a transverse longitudinal axis 191, which may also be referred to as a first transverse axis. The motion limiter also includes a stop bar 13 attached to the attachment segment 14. The stop bar has a first side 131 and a second side 132.

[0025] In this disclosure, the term "rod" refers to any structure that can be attached to an attachment segment such that the rod can rotate out of the plane of the device when the attachment segment is twisted. The rod can have an elongated shape, as illustrated in the accompanying drawings of this disclosure. However, many other shapes are also possible. At least in contrast to the torsional flexible portion, the rod can be rigid in the out-of-plane direction, such that most deformation in the motion limiter occurs primarily in the torsional flexible portion. Alternatively, however, the rod can have some degree of out-of-plane flexibility.

[0026] In a horizontal plane, the lateral direction is perpendicular to the transverse direction. The lateral direction is illustrated below. Figure 1a The x-direction in the middle. Stop bar 13 in Figure 1a The stop bar extends in the lateral direction, but it may alternatively extend in any other direction in the xy plane, provided that the stop bar can undergo out-of-plane rotation about the attachment segment 14.

[0027] Figure 1a The connecting section 15 is also illustrated. The connecting section is also torsionalally flexible about axis 192, which may be referred to as the second transverse axis. Therefore, when the first device portion 11 and the second device portion 12 undergo relative vertical movement (i.e., when one of them moves upward or downward), the attachment section 14 and the connecting section 15 will adapt to this movement by torsional flexibility. This torsion allows the stop bar 13 to rotate about the first transverse axis 191, causing the two sides of the stop bar to move in opposite vertical directions. This movement will be described and explained in more detail below. The attachment section 14 and the connecting section 15 can be implemented, for example, as torsion bars. A torsion bar is a structure with a length / width / height aspect ratio that favors torsional twisting. Alternatively, the attachment section and the connecting section can be implemented using other types of torsional flexible elements, such as bending springs.

[0028] The motion limiter also includes a stop element 16 located on the stop bar. The stop element may, for example, be simply the end of the stop bar, but alternatively, the stop element may be an extension of the stop bar in the xy plane (as illustrated) and / or along the z direction (as shown below). Figure 2e (See diagram) A protruding stop bump. The stop element can be located at the end of the stop bar (as shown in the diagram), but alternatively, if the stop element is a protrusion projecting from the stop bar in the z-direction, the stop element can be located at other positions on the second side 132 of the stop bar. As mentioned above, the stop element should be the first part of the motion limiter to come into contact with the platform structure when the rotor has moved sufficiently far in the vertical direction.

[0029] The first attachment segment 14 can be aligned on the first transverse axis 191, the stop element 16 can be aligned on the third transverse axis 193, and the attachment point of the connecting segment 15 on the first side 131 of the stop rod 13 can be aligned on the second transverse axis 192. The lateral distance from the first transverse axis 191 to the second transverse axis 192 can be less than the lateral distance from the first transverse axis 191 to the third transverse axis 193.

[0030] The connecting section 15 can extend laterally from the edge 121 of the second device portion 12 to the first side portion 131 of the stop bar 13, such as Figure 1a Illustration. In this case, the connecting part 15 is simply a torsional flexible, laterally oriented torsion bar.

[0031] Figure 1b An alternative device is illustrated, wherein the connecting section 15 includes a torsionally flexible second attachment section 151 attached to the edge 121 of the second device portion 12. The second attachment section 151 extends laterally toward the first device portion 11. The connecting section 15 also includes a torsionally flexible third attachment section 153 attached to an attachment point on a first side 131 of the stop bar 13. The connecting section 15 also includes a connecting rod 152 extending from the second attachment section 151 to the third attachment section 153. The second attachment section 151 may, but does not necessarily, be aligned on the first transverse axis 191.

[0032] Figure 1c The diagram illustrates a fixed wall 171 located above the device plane. A first or second device portion, serving as a rotor (11 / 12), is positioned in its rest position, and the rotor is separated from the fixed wall 171 by a rotor-wall gap 182. The fixed wall can be, for example, a surface on a support wafer adjacent to the device layer and providing mechanical support for the device layer on one or more edges (not shown) of the device. Alternatively, the fixed wall can be a surface on a cap wafer positioned adjacent to the device layer or an inner surface of the package structure.

[0033] The fixed wall adjacent to the device layer typically forms an enclosure around the rotor. In order to prevent direct contact between the rotor 11 / 12 and any vertically adjacent fixed wall 171 when the rotor 11 / 12 is displaced out of plane near a given threshold (which may be close to the vertical rotor-wall gap), the motion limiter designed so that the stop element 16, which contacts the table structure before the rotor 11 / 12, can contact the fixed wall.

[0034] The motion limiter is constructed in the gap between the rotor (11 / 12) and the stationary stator (12 / 11). The stationary stator is located in a horizontal device plane. The stationary stator can be any fixed structure positioned adjacent to the rotor. If the device layer is formed in a device wafer, the stationary stator can be a fixed portion of that wafer. A flexible suspension structure supporting the weight of the movable rotor can extend between the stationary stator and the movable rotor. However, alternatively, this suspension structure can be attached to some other fixed structure besides the stationary stator to which the motion limiter is attached.

[0035] As mentioned above, the device part referred to as the "first device part" can be a movable stator or a fixed rotor. These two cases will now be discussed in detail with reference to the accompanying drawings.

[0036] The first device part is an embodiment of a movable rotor.

[0037] In this embodiment, the first device part is a movable rotor, the second device part is a fixed stator, and the fixed wall and the platform structure are located on the same side of the device plane. In this case, the second end of the stop bar will move in the same direction as the movable rotor.

[0038] Figures 2a to 2c It is shown that when the first part of the device is a movable rotor, along Figure 1a and Figure 1b The cross sections of lines CC and AA in the figure. Reference numerals 21, 23, 24, 25, 26, and 271 correspond to... Figures 1a to 1c The figures are labeled 11, 13, 14, 15, 16 and 171.

[0039] Figure 2a The position of the stop bar 23 is shown when the rotor is in its rest position in the xy plane. The first attachment section 24 is separated from the fixed wall 271 by a vertical first separation gap 283, and the stop element 26 is separated from the fixed wall 271 by a stop gap 284.

[0040] Here, fixed wall 271 is used as Figures 2a to 2c The diagram shows the platform structure in the motion limiter. The stop element 26 is located at the very end of the stop rod 23 and has the same vertical height as the stop rod 23. Furthermore, since the stop rod 23 is horizontal in the xy plane when the rotor is in its stationary position, the vertical height of the first separation gap 283 and the stop gap 284 is equal to... Figure 1c Vertical height of the rotor-wall clearance 182.

[0041] The operation diagram of the motion limiter is shown in Figure 2b and Figure 2c middle. Figure 2bThis illustrates that when the movable rotor 21 has moved toward the fixed wall 271 such that the vertical height of the second separation gap 285 between the rotor 21 and the wall 271 is less than... Figure 1c The vertical height of the rotor-wall clearance 182 is based on Figures 1a to 1b AA cross section.

[0042] The first attachment section 24 is rigidly attached to the movable rotor 21 and moves upward with the rotor. Figure 2c This shows when the movable rotor 21 is located Figure 2b When the position shown in the middle diagram is Figures 1a to 1b The vertical height of the third separation gap 286 between the first attachment segment 24 and the fixed wall 271 is equal to the CC cross section. Figure 2b The vertical height of the second separation gap 285 in the middle.

[0043] However, the connecting section 25 remains attached to the fixed stator, which remains in the xy plane. If the connecting section 25 is very rigid in the vertical direction, the vertical height of the fourth separation gap 287 can still be... Figure 1c The rotor-wall clearance 182 is the same. The movement of the rotor generates a torque that causes the stop bar to rotate about the first transverse axis 191. In the illustrated case, the required flexible deformation in the motion limiter to accommodate the out-of-plane movement of the movable rotor 21 is the torsional deformation of 24 and 25.

[0044] Alternatively, the connecting section can have a slight vertical flexibility but still be rigid enough to pull the first end of the stop bar 23 below the rotor 21 as the rotor moves upward, such that the fourth separation gap 287 obtains a value between 182 and 286 when the rotor has already moved upward. In this case, the torque required to rotate the stop bar will be less than the torque required if the connecting section were vertically rigid, but the stop bar 23 will still rotate, causing the stop element 26 to move to a higher z-coordinate than the rotor 21. In this case, the flexible deformation can be a combination of torsional deformation of 24 and 25 and vertical bending of 25.

[0045] exist Figure 2c In the middle, the rotation of the stop bar 23 causes the stop element 26 to contact the fixed wall 271. Thus, the motion limiter rigidly resists further upward movement of the movable rotor 21. If the stop bar 23 has some vertical flexibility, it can bend slightly and the resistance can have a certain degree of elasticity.

[0046] The stop bar 23, the stop element 26, and the stop gap 284 shall be sized such that the stop element 26 contacts the platform structure 271 across the stop gap 284 before the movable rotor 21 makes direct physical contact with the fixed wall 371 across the rotor-wall gap.

[0047] exist Figures 2a to 2c In the case illustrated, the stop element 26 will make early contact with the fixed wall because the lateral distance from the first transverse axis to the second transverse axis is less than the lateral distance from the first transverse axis to the third transverse axis. In other words, in the x-direction, Figure 2a The distance between 24 and 25 is less than the distance between 26 and 24. The rate at which the stop element 26 moves toward the fixed wall 271 will be greater than the rate at which the movable rotor 21 moves toward the fixed wall 271, but the motion limiter begins to resist the rotor's movement earlier, before the rotor can acquire a large amount of momentum in the vertical direction. This reduces the likelihood of damage when the stop element impacts the fixed wall 271.

[0048] Figure 2d An alternative option using a separate platform structure 272 is illustrated. Platform structure 272 is a protrusion extending from the fixed wall toward the stop element 26. Additionally, here, the stop element 26 extends vertically from the stop rod 23 toward the fixed wall 271. If either of these two alternatives (the platform structure extending from the fixed wall toward the stop element, or the stop element extending toward either the platform structure or the fixed wall) is applied, the vertical height of the stop clearance 284 can be less than the vertical height of the rotor-wall clearance when the rotor is in its rest position.

[0049] The early collision operation principle of the motion limiter can be achieved through Figure 2d The device illustrated is implemented even when the lateral distance from the first lateral axis to the second lateral axis is greater than the lateral distance from the first lateral axis to the third lateral axis. This illustration is in... Figure 2e In the middle. The relative motion (rotation angle ratio) of rotor rod 23 with respect to the movable rotor. Figure 2c The rotation angle in the middle is smaller than that in the middle. Figure 2c The relative motion is slow, but the stop element 26 can still contact the platform structure in the early stages of motion. By appropriately sizing the stop bar 23, the stop element 26, and / or the platform structure 272, the motion limiter can be arranged to restrict the motion of the movable rotor before the movable rotor has acquired significant momentum.

[0050] The second device is an implementation of a movable rotor.

[0051] In this embodiment, the second device part is a movable rotor, the first device part is a fixed stator, and the fixed wall and platform structure are located on opposite sides of the device plane. In this case, the second end of the stop bar will move in the opposite direction to the direction of movement of the movable rotor.

[0052] Figures 3a to 3c It is shown that when the first part of the device is a movable rotor, along Figure 1a and Figure 1b The cross-sections of lines CC and BB in the figure. Reference numerals 32, 33, 34, 35, 36, and 371 correspond to... Figures 1a to 1c The figures are labeled 12, 13, 14, 15, 16 and 171.

[0053] Figure 3a The position of the stop bar 33 is shown when the rotor is in its rest position in the xy plane. As in the previous embodiment, the first attachment segment 34 is separated from the fixed wall 371 by a vertical first separation gap 383. Unlike the previous embodiment, in this case, the platform structure 372 is located below the stop element 36. The stop element is separated from the platform structure 372 by a stop gap 384.

[0054] The platform structure 372 can be, for example, a fixed wall located below the rotor and motion limiter; however, alternatively, the platform structure can be any smaller fixed structure located below the motion limiter. When the rotor 32 is in its rest position, the vertical height of the first separation gap 383 is equal to... Figure 1c The vertical height of the rotor-wall clearance 182. On the other hand, the vertical height of the stop clearance 384 can be any suitable value given.

[0055] The operation diagram of the motion limiter is shown in Figure 3b and Figure 3c middle. Figure 3b This shows that the vertical height of the second separation gap 385 between the movable rotor 32 and the fixed wall 371 is less than the height of the fixed wall 371 after the movable rotor 32 has moved toward the fixed wall 371. Figure 1c The vertical height of the rotor-wall clearance 182 is based on Figures 1a to 1b BB cross section.

[0056] The first attachment section 34 is rigidly attached to the fixed stator (the stator is not shown in the figure). Figures 3a to 3c Therefore, when rotor 32 moves, the first attachment section must remain horizontal in the xy plane. Figure 3c This shows the movable rotor 32 located at Figure 3b The position shown in the middle diagram is based on Figures 1a to 1b The vertical height of the third separation gap 383 between the first attachment section 34 and the fixed wall 371 remains unchanged.

[0057] On the other hand, the connecting section 35 has now moved upward via the movable rotor 32. Therefore, the first side of the stop rod 33 has also moved upward, and this movement causes the second side of the stop rod 33 to move downward, as... Figure 3c The diagram illustrates this. If the connecting section 35 is very rigid in the vertical direction, then the vertical height of the third separation gap 389 can be the same as... Figure 3b The second separation gap 385 is at the same vertical height. The movement of rotor 32 generates a torque that causes stop bar 33 to rotate about the first transverse axis 191. In the illustrated case, the flexible deformation required in the motion limiter to accommodate the out-of-plane movement of movable rotor 32 is the torsional deformation of 34 and 35.

[0058] As in the previous embodiment, the connecting section 35 may have some vertical flexibility, but still possess sufficient rigidity to raise the first end of the stop bar 33 above the device plane when the rotor 32 moves upward, such that the third separation gap 389 obtains a value between 383 and 385 when the rotor 32 has already moved upward. In this case, the torque required to rotate the stop bar 33 will be less than the torque required if the connecting section were vertically rigid, but the stop bar 33 will still rotate, causing the stop element 36 to move to a z-coordinate lower than the stator. In this case, the flexible deformation can be a combination of torsional deformation of 34 and 35 and vertical bending of 35.

[0059] exist Figure 3c In the middle, the rotation of the stop bar 33 causes the stop element 36 to contact the platform structure 372. Since the stop bar 33 will no longer rotate, the motion limiter now rigidly resists further upward movement of the movable rotor 32. If the stop bar 33 has some vertical flexibility, the stop bar can bend slightly and the resistance can have a certain degree of elasticity.

[0060] The stop bar 33, the stop element 36, and the stop gap 384 shall be sized such that the stop element 36 contacts the platform structure 372 across the stop gap 384 before the movable rotor 32 makes direct physical contact with the fixed wall 371 across the rotor-wall gap.

[0061] As in the previous embodiment, the lateral distance from the first lateral axis to the second lateral axis can be less than the lateral distance from the first lateral axis to the third lateral axis. This is illustrated in... Figure 3a In this case, the distance between 34 and 35 in the x-direction is less than the distance between 36 and 34. Therefore, the rate at which the stop element 36 moves toward the platform structure 372 will be greater than the rate at which the movable rotor 32 moves toward the fixed wall 371. The motion limiter begins to resist the rotor's movement earlier, before the rotor can acquire sufficient momentum in the vertical direction. This reduces the likelihood of damage when the stop element 36 impacts the platform structure 372.

[0062] However, the stop element can be configured to make early contact with the platform structure even without applying the aforementioned distance relationship. This will depend on the size of the stop gap 384. If necessary, the stop element 36 can extend downward from the stop rod 33 toward the platform structure 372, thereby reducing the stop gap 384. Alternatively, the platform structure 372 can be positioned closer to the stop gap in other ways, such as by constructing a protrusion below the stop element 36. By appropriately dimensionalizing the stop gap 384, the motion limiter can be arranged to restrict the movement of the movable rotor 32 before the movable rotor has acquired significant momentum.

[0063] Linear and rotary rotor motion

[0064] A movable rotor can undergo linear out-of-plane motion, such as... Figure 2b and Figure 3b As illustrated in the diagram. However, the same motion limiter principle can also be achieved when the movable rotor undergoes out-of-plane rotation toward the fixed wall, provided that the first attachment section (in the embodiment where the first device part is a movable rotor) or the connecting section (in the embodiment where the second device part is a movable rotor) is attached to the side of the rotor that rotates upward toward the fixed wall during rotational motion (not attached to the side that rotates away from the fixed wall).

[0065] In other words, if the rotor will undergo rotational motion, in Figure 2b In the process, the rotor will rotate out of the device plane such that the rotor portion to which the first attachment segment 24 is attached will be at a distance 285 as shown in the figure from the fixed wall 271. The motion limiter will then... Figure 2c Running in. Correspondingly, in Figure 3b In the process, the rotor will rotate out of the device plane such that the rotor portion attached to the connecting section 35 will be at a distance 385 from the fixed wall 371 as shown in the figure. The motion limiter will then... Figure 3c It is running in the middle.

[0066] If both sides can rotate toward the fixed wall during rotational motion, then two separate motion limiters can be implemented on opposite sides of the rotor.

[0067] Multiple motion limiters

[0068] Two or more motion limiters can be constructed in the gap between the edges of the rotor and the stator. Additional motion limiters can be constructed between the opposite edge of the rotor and the edge of another stator adjacent to that edge of the rotor. Generally, any drawbacks that might arise from the asymmetrical action of a single motion limiter can be avoided by arranging multiple motion limiters approximately symmetrically around the rotor. Optimal symmetry will depend on the expected out-of-plane motion of the rotor and other device design considerations.

Claims

1. A microelectromechanical device (MEMS) comprising a movable rotor and a fixed stator, the movable rotor being located in a rest position in a horizontal device plane, the fixed stator being positioned adjacent to the movable rotor in the horizontal device plane, and the device further comprising a fixed wall defining a wall plane adjacent to the horizontal device plane, wherein, The fixed wall and the movable rotor are separated in the vertical direction by a rotor-wall gap, wherein the vertical direction is perpendicular to the horizontal plane of the device. The device further includes a motion limiter and a platform structure, wherein the motion limiter includes a stop element, and the platform structure is adjacent to and vertically separated from the horizontal device plane, and the stop element and the platform structure are separated by a vertical stop gap when the movable rotor is located in the horizontal device plane. Furthermore, as the movable rotor undergoes movement in the vertical direction toward the fixed wall, the device causes the stop element to contact the platform structure across the stop gap before the movable rotor contacts the fixed wall across the rotor-wall gap. Its features are, - The movable rotor is a first device part and the fixed stator is a second device part, or The movable rotor is a second part of the device, and the fixed stator is a first part of the device. Furthermore, in the horizontal plane of the device, the edges of the first device portion and the second device portion are separated by a rotor-stator gap extending in the lateral direction, and the motion limiter extends across the rotor-stator gap from the first device portion to the second device portion, and the motion limiter includes a torsionally flexible first attachment segment and a stop bar, the first attachment segment extending in the lateral direction from the edge of the first device portion toward the second device portion, and the stop bar being attached to the attachment segment. Furthermore, the first side of the stop bar extends from the attachment section along a first lateral direction, and the second side of the stop bar extends from the attachment section along a second lateral direction, wherein the second lateral direction is opposite to the first lateral direction, and the stop bar includes a stop element located on the second side of the stop bar, and the motion limiter further includes a torsional flexible connecting section that extends from the edge of the second device portion to the first side of the stop bar.

2. The microelectromechanical device according to claim 1, characterized in that, The first attachment segment is aligned on the first transverse axis, the stop element is aligned on the third transverse axis, the attachment point of the connecting segment on the first side of the stop bar is aligned on the second transverse axis, and the lateral distance from the first transverse axis to the second transverse axis is less than the lateral distance from the first transverse axis to the third transverse axis.

3. The microelectromechanical device according to any one of claims 1 to 2, characterized in that, The connecting section extends from the edge of the second device portion along the lateral direction to the first side of the stop bar.

4. The microelectromechanical device according to any one of claims 1 to 2, characterized in that, The connecting section includes a torsional flexible second attachment section attached to the edge of the second device portion and extending toward the first device portion in the lateral direction, and the connecting section also includes a torsional flexible third attachment section attached to an attachment point on the first side of the stop bar, and the connecting section also includes a connecting rod extending from the second attachment section to the third attachment section.

5. The microelectromechanical device according to any one of claims 1 to 4, characterized in that, The first device part is the movable rotor, the second device part is the fixed stator, and the fixed wall and the platform structure are located on the same side of the device plane.

6. The microelectromechanical device according to any one of claims 1 to 4, characterized in that, The second device part is the movable rotor, the first device part is the fixed stator, and the fixed wall and the platform structure are located on opposite sides of the device plane.

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