Memsm device with damping and stop multifunction structure

Abstract

Embodiments of the present disclosure relate to MEMS devices with damping and stop multifunctional structures. A microelectromechanical device includes a support body and a movable mass constrained to the support body with a degree of freedom relative to a first direction parallel to the support body and including a frame portion delimiting an opening. A damping and stop structure is anchored to the support body and housed in the opening. The movable mass includes first elongated elements defined by respective plates perpendicular to the first direction and extending in the opening from the frame portion in a comb configuration. The damping and stop structure includes second elongated elements anchored to the support body, defined by respective plates perpendicular to the first direction, and extending toward the frame portion of the movable mass in a comb configuration. The second elongated elements are interleaved with the first elongated elements. The damping and stop structure further includes a stop element limiting movement of the movable mass along the first direction.

Description

Priority Statement

[0001] This application claims priority to Italian Patent Application No. 102025000003153, filed on February 18, 2025, the contents of which are incorporated herein by reference in their entirety to the fullest extent permitted by law. Technical Field

[0002] This disclosure relates to microelectromechanical (MEMS) devices, and more particularly to MEMS gyroscopes having multifunctional damping and stopping structures. Background Technology

[0003] As is well known, many MEMS devices utilize the movement of one or more movable structures (often referred to as "movable mass" or "test mass") relative to a support to sense changes in physical quantities (as in MEMS devices such as inertial sensors) or to act as actuators.

[0004] In response to potential shocks during the lifespan of a MEMS device, the movable mass may exceed its considered safe operating position. To prevent structural damage, a stop structure (also known as a "stopper") is provided to limit the permissible displacement of the movable mass. The stop structure is typically anchored to a support structure via anchoring elements (or simply "anchors"). The anchors of the stop structure must be mechanically robust enough to withstand impacts between the stop structure and the movable mass; this typically results in relatively large anchors.

[0005] In inertial sensors such as gyroscopes, a movable mass is configured to oscillate in a controlled manner along the drive direction and, in response to rotation of the support about a rotation axis perpendicular to the drive direction, to oscillate along a sensing direction perpendicular to both the drive direction and the rotation axis. To maintain the sensing response specifically according to design preferences, controlling the vibration immunity index in a gyroscope is crucial: typically, a trade-off needs to be made between the quality factor Q of the sensing transfer function and maintaining both high oscillation performance (meaning a high quality factor Q) and low vibration sensitivity (meaning a low quality factor Q).

[0006] A typical solution in gyroscopes that allows for a reduction in the quality factor Q is the use of a damping structure (also known as a "damper"). This damping structure is coupled to a movable mass and a support, and is configured to reduce the displacement of the movable mass along the sensing direction caused by vibration through mechanical damping action. For example, known "in-plane" damping structures can be used for gyroscopes capable of sensing rotation about an "out-of-plane" axis. However, for significant effectiveness, damping structures typically require a relatively large footprint within the sensor.

[0007] Alternative solutions, such as performing a sealed operation of the sensor in a chamber with high pressure and / or a specific gas mixture, risk causing the quality factor Q to decrease along the drive direction as well, while the quality factor along the drive direction needs to be kept high to allow the movable mass block to be properly held in controlled oscillations.

[0008] Therefore, the drawback of both the stop and damping structures in current MEMS gyroscopes is space consumption. More generally, this drawback exists in MEMS devices (such as inertial sensors and actuators), which require stop structures for movable mass blocks and damping structures for the movable mass blocks to oscillate along at least one direction. Summary of the Invention

[0009] Therefore, one object of this disclosure is to overcome or at least partially mitigate the disadvantages and limitations of the prior art.

[0010] According to this disclosure, a MEMS device having a multifunctional damping and stopping structure as defined in the appended claims is proposed.

[0011] For example, a microelectromechanical device (MEMS) includes: a support body; a movable mass block constrained to the support body with relative degrees of freedom with respect to at least a first direction, the first direction being parallel to the support body; and a frame portion defining an opening. A damping and stopping structure is anchored to the support body and received within the opening of the movable mass block. The movable mass block includes a first elongated element defined by a corresponding plate perpendicular to the first direction and extending from the frame portion in a comb-like configuration within the opening. The damping and stopping structure includes a second elongated element anchored to the support body, defined by a corresponding plate perpendicular to the first direction, and extending toward the frame portion of the movable mass block in a comb-like configuration, wherein the second elongated element intersects with the first elongated element. The damping and stopping structure also includes a stopping element configured to restrict movement of the movable mass block along at least the first direction.

[0012] Optionally, the first elongated element can be rigidly fixed to the movable mass block, and the first elongated element and the second elongated element can form a viscous damper for the movable mass block along a first direction.

[0013] Optionally, the device may be a gyroscope, and the movable mass may have another degree of freedom relative to a second direction, which is parallel to the support and perpendicular to the first direction. The device may include an actuator configured to keep the movable mass oscillating along the second direction, and the movable mass may be constrained to the support to oscillate along the first direction in response to rotation about a rotation axis perpendicular to the support.

[0014] Optionally, the stopping element of the damping and stopping structure may include a contact portion that protrudes toward the frame portion of the movable mass block.

[0015] Optionally, the damping and stopping structure may include a first anchor of an elongated shape, the first anchor being parallel to a first direction, wherein the second elongated element is supported by the first anchor.

[0016] Optionally, the damping and stopping structure may include an elongated second anchor, which is parallel to a second direction that is parallel to the support and perpendicular to the first direction.

[0017] Alternatively, the stopping element of the damping and stopping structure may protrude from a corresponding one of the first and second anchors toward the frame portion of the movable mass block.

[0018] Optionally, the first anchor and the second anchor can form a single body.

[0019] Optionally, the first anchor of the damping and stopping structure may extend substantially parallel to a first side of the frame portion of the movable mass block, the first sides of the frame portion of the movable mass block being opposite each other in a second direction, and the second anchor may extend substantially parallel to a second side of the frame portion, the second sides of the frame portion being opposite each other in a first direction.

[0020] Optionally, the first elongated element of the movable mass block may include a first group and a second group of first elongated elements, wherein the first elongated elements of the first group and the first elongated elements of the second group extend from respective first sides of the frame portion. A first anchor of the damping and stopping structure may be disposed between the first group and the second group of first elongated elements and at a distance from both groups. The second elongated element of the damping and stopping structure may include a first group and a second group of second elongated elements, wherein the second elongated elements of the first group and the second elongated elements of the second group extend from respective sides of the first anchor along a second direction opposite to each other. The second elongated elements of the first group may intersect with the first elongated elements of the first group, and the second elongated elements of the second group may intersect with the first elongated elements of the second group.

[0021] Optionally, each of the first elongated elements in the first group can be aligned with a corresponding first elongated element in the second group along the second direction, and each of the second elongated elements in the first group can be aligned with a corresponding second elongated element in the second group along the second direction.

[0022] Optionally, the first anchor may be arranged substantially centrally in the opening of the movable mass block, and the second anchor may include two arms extending from opposite sides relative to the end of the first anchor, and the second anchor is arranged as one of the second sides of a second side adjacent to the frame portion of the movable mass block.

[0023] Optionally, the stop element may include a first stop element protruding from a first anchor and a second stop element protruding from a second anchor, wherein the second stop element and the first stop element protrude toward a corresponding second side of the frame portion.

[0024] Optionally, a first elongated element of the movable mass block may extend from one of the first sides of the frame portion, and a second elongated element of the damping and stopping structure may extend from one of the first sides of the first anchor facing the frame portion. The first anchor may be arranged adjacent to another of the first sides of the frame portion, and the second anchor may be arranged adjacent to one of the second sides of the frame portion.

[0025] Optionally, the stop element may include a first stop element and a second stop element, the first stop element protruding from the first anchor toward the other first side of the first side of the frame portion, and the second stop element protruding from the second anchor toward the second side of the frame portion, wherein the first stop element is configured to restrict movement of the movable mass block in a second direction, and the second stop element is configured to restrict movement of the movable mass block in a first direction.

[0026] A method for operating a microelectromechanical device (MEMS) is also provided, the MEMS comprising: a support; a movable mass block constrained to the support with a degree of freedom along a first direction; and a damping and stopping structure anchored to the support and received within an opening in the movable mass block. The method includes: oscillating the movable mass block along the first direction; damping the oscillation of the movable mass block along the first direction by providing viscous friction between an interlaced first elongated element fixed to the movable mass block and a second elongated element anchored to the support; and limiting the displacement of the movable mass block along the first direction by contacting a stopping element of the damping and stopping structure with the movable mass block when the displacement of the movable mass block along the first direction exceeds a predetermined range.

[0027] Optionally, the method may include: using an actuator to drive a movable mass block to oscillate in a controlled manner along a second direction, the second direction being perpendicular to the first direction; and sensing a physical quantity by detecting the movement of the movable mass block along the first direction in response to rotation of the support about an axis perpendicular to the support.

[0028] Optionally, the damping and stopping structure may include a first anchor and a second anchor, the first anchor extending parallel to a first direction and the second anchor extending parallel to a second direction perpendicular to the first direction. The method may further include: anchoring a second elongated element to the first anchor and providing a stopping element projecting from at least one of the first and second anchors toward the movable mass block.

[0029] Optionally, the method may include: configuring a stop element to restrict movement of the movable mass along both a first direction and a second direction, the second direction being perpendicular to the first direction, by providing a stop element protruding from the damping and stop structure toward a corresponding side of the movable mass.

[0030] Alternatively, the method may include adjusting the size and arrangement of the first elongated element, the second elongated element, and the anchors of the damping and stopping structure to achieve a desired balance between damping effectiveness and impact mechanical robustness, while minimizing the area occupied within the equipment. Attached Figure Description

[0031] To better understand the invention, preferred embodiments are given by way of non-limiting example with reference to the accompanying drawings, in which:

[0032] Figure 1 A MEMS device according to an embodiment of the invention and a driving mode is schematically shown in a plan view;

[0033] Figure 2 The plan view schematically illustrates the effect based on the sensing mode. Figure 1 MEMS devices;

[0034] Figure 3 An embodiment of the invention is schematically illustrated in the plan view. Figure 1 Amplification section of MEMS devices; and

[0035] Figure 4 Different embodiments of the invention are schematically illustrated in the plan view. Figure 1 The amplification section of MEMS devices. Detailed Implementation

[0036] The following description refers to the arrangement shown in the figures; therefore, expressions such as “above,” “below,” “upper part,” “lower part,” “top,” “bottom,” “right,” “left,” etc., are related to the figures and should not be interpreted in a restrictive manner.

[0037] Figure 1 and Figure 2 A microelectromechanical (MEMS) device, hereinafter also simply referred to as "device," according to an embodiment of the present invention, is shown and is generally indicated by reference numeral 1, and includes a support 2 and a MEMS structure 3. Specifically, without being considered limiting, the following description and... Figure 1 and Figure 2 The device 1 shown schematically is a three-axis MEMS gyroscope (which can also be configured for six-axis inertial sensing); therefore, in the following text, device 1 and gyroscope 1 will be referred to interchangeably. However, it is obvious that the following description, in particular Figure 3 and Figure 4 The content shown can be applied to, except for Figure 1 and Figure 2 Other inertial MEMS devices besides the gyroscope 1.

[0038] Considering the orthogonal reference frames X, Y, and Z, the support 2 and the MEMS structure 3 have corresponding main extensions parallel to the XY plane. Furthermore, the MEMS structure 3 is symmetrical about a first axis of symmetry M1 parallel to the Y-axis and about a second axis of symmetry M2 parallel to the X-axis. The support 2 and the MEMS structure 3 are formed of semiconductor materials, for example, both are made of silicon. The MEMS structure 3 includes an assembly of driving and sensing mass blocks, which are movable relative to the support 2; that is, the movable mass blocks of the MEMS structure 3 are constrained to the support 2 with relative degrees of freedom with respect to at least one direction of motion.

[0039] The MEMS structure 3 specifically includes a first driving mass block D1 and a second driving mass block D2. The first driving mass block D1 and the second driving mass block D2 form a first pair of driving mass blocks D1 and D2, which are arranged on the same side of the MEMS structure 3 relative to the second axis of symmetry M2 and aligned along the X-axis. The first pair of driving mass blocks D1 and D2 are each coupled to a corresponding common driving anchor 31 via a corresponding anchoring elastic element 32. The driving anchor 31 is fixed to the support body 2 and is arranged at an intermediate position between the first driving mass block D1 and the second driving mass block D2 along the first axis of symmetry M1. The anchoring elastic element 32 is, for example, a folded type or a bellows type.

[0040] MEMS structure 3 also includes a third driving mass block D3 and a fourth driving mass block D4, which form a second pair of driving mass blocks D3 and D4. These are arranged on opposite sides of MEMS structure 3 relative to the second axis of symmetry M2 and aligned along the X-axis. The second pair of driving mass blocks D3 and D4 are arranged symmetrically with respect to the second axis of symmetry M2 to the first pair of driving mass blocks D1 and D2. The second pair of driving mass blocks D3 and D4, in a completely symmetrical manner with the first pair of driving mass blocks D1 and D2, are also each coupled to a corresponding common driving anchor 31 via a corresponding anchoring elastic element 32. Specifically, the driving anchor 31 is fixed to the support body 2 and is arranged along the first axis of symmetry M1 at an intermediate position between the third driving mass block D3 and the fourth driving mass block D4.

[0041] In a manner not illustrated in detail here, the first and second pairs of driving mass blocks D1, D2, D3, and D4 can each define a window or opening within them for a movable driving electrode. The movable driving electrode is coupled to the same mass block (or in any case integrated with it) and interleaved with a corresponding fixed driving electrode arranged in the same window. In a manner known per se, the capacitive interaction between the interleaved driving electrodes determines the driven movement of the MEMS structure 3, as described in more detail below. Specifically, the driven movement of the first and second pairs of driving mass blocks D1, D2, D3, and D4 occurs “in-plane,” more specifically along the X-axis.

[0042] MEMS structure 3 also includes a first pitch sensing mass block P1 and a second pitch sensing mass block P2. The first pitch sensing mass block P1 and the second pitch sensing mass block P2 form a pair of pitch sensing mass blocks P1, P2, which are symmetrically arranged with respect to a first axis of symmetry M1. The drive mass blocks D1, D2, D3, and D4 of the first and second pairs are located externally (along the X-axis) and extend along the Y-axis in length, spanning a second axis of symmetry M2 (symmetrical with respect to the same second axis of symmetry M2). The pitch sensing mass blocks P1 and P2 are used in device 1 to sense pitch angular velocity.

[0043] The first pitch sensing mass P1 is elastically coupled to both the first driving mass D1 and the third driving mass D3 (i.e., driving mass blocks arranged on the same side of the MEMS structure 3 relative to the first axis of symmetry M1) via corresponding coupling elastic elements 33. Similarly, the second pitch sensing mass P2 is elastically coupled to both the second driving mass D2 and the fourth driving mass D4 via corresponding coupling elastic elements 33. Furthermore, the pitch sensing masses P1 and P2 are elastically constrained to the support 2 by corresponding pitch anchors 34, which are connected by... Figure 1 and Figure 2A specific window, not shown in detail, is centrally positioned over pitch sensing mass blocks P1 and P2. Specifically, each pitch sensing mass block P1 and P2 is elastically connected to a corresponding pitch anchor 34 via a flexible coupling arrangement (also not shown in the figures), which defines an axis of rotation (parallel to the X-axis) for “out-of-plane” rotation of the same pitch sensing mass block relative to the XY plane.

[0044] The coupling elastic element 33 of the MEMS structure 3 is typically configured to convert the translational driven movement of the first and second pairs of driving mass blocks D1, D2, D3, D4 into rotational movement of the pitch sensing mass blocks P1, P2 in the XY plane (about the corresponding pitch anchor 34), allowing them to produce "out-of-plane" sensing movement due to Coriolis forces in the presence of pitch angular velocity about the Y-axis. In a non-limiting embodiment, each of the coupling elastic elements 33 includes, for example, a linear central portion (in... Figure 1 In the example along the X-axis), the linear central portion is elongated and rigid in the same direction to convert the driven movement of the corresponding drive mass into the movement of the pitch sensing mass; and the end portion, which is arranged at the far end of the aforementioned central portion, is coupled to one of the drive mass blocks and the corresponding pitch sensing mass respectively, is elastic for “out-of-plane” movement relative to the XY plane and produces “out-of-plane” movement relative to the XY plane, and has, for example, a folded shape, a bellows shape or a serpentine shape along the X-axis.

[0045] A corresponding fixed electrode is arranged below the pitch sensing mass blocks P1 and P2 (in a manner not shown in the attached figure). The fixed electrode is capacitively coupled to the pitch sensing mass blocks P1 and P2 and is placed on or integrated with the support 2 (thus providing a differential pitch sensing scheme of a known type, which is not described in detail here).

[0046] MEMS structure 3 also includes a first roll sensing mass block R1 and a second roll sensing mass block R2, forming a pair of roll sensing mass blocks R1, R2. The roll sensing mass blocks R1 and R2 are symmetrically arranged on opposite sides of a first axis of symmetry M1 and elastically connected to each other by a coupling elastic element 35. The coupling elastic element 35 is arranged along a second axis of symmetry M2 and has sufficient stiffness to allow the roll sensing mass blocks R1 and R2 to move (described in detail below) while simultaneously holding them constrained to each other during their movement. The roll sensing mass blocks R1 and R2 are located at the center of MEMS structure 3, inside the first and second pairs of drive mass blocks D1, D2, D3, and D4. The roll sensing mass blocks R1 and R2 are used in device 1 to sense roll angular velocity.

[0047] Each of the roll sensing mass blocks R1 and R2 has a generally rectangular shape in the plane, for example, and a window at the center (not shown for simplicity), within which a corresponding roll anchor 36 is arranged. Each of the roll sensing mass blocks R1 and R2 is coupled to the corresponding roll anchor 36 by an elastic coupling arrangement (not shown for simplicity), which defines a rotation axis (parallel to the Y-axis) for "out-of-plane" sensing movement relative to the XY plane.

[0048] Furthermore, the first roll sensing mass R1 is elastically coupled to the first drive mass D1 and the third drive mass D3 via corresponding coupling elastic elements 37, which extend from the respective opposite sides of the first roll sensing mass R1 and are aligned along the Y-axis. Figure 1 and Figure 2 As illustrated, such a coupling elastic element 37 can be, for example, linear. Similarly, the second roll sensing mass R2 is elastically coupled to the second drive mass D2 and the fourth drive mass D4 by corresponding coupling elastic elements 37, which extend from the respective opposite sides of the second roll sensing mass R2 and are aligned along the Y-axis (e.g., linear).

[0049] A corresponding fixed electrode is arranged below the roll sensing mass blocks R1 and R2 (in a manner not shown in the figures). The corresponding fixed electrode is capacitively coupled to the roll sensing mass blocks R1 and R2 and is placed on or integrated with the support 2 (to provide a differential roll sensing scheme of a known type, which is not described in detail here).

[0050] The MEMS structure 3 ultimately includes: a first yaw sensing mass block Y1 and a second yaw sensing mass block Y2, forming a first pair of yaw sensing mass blocks Y1 and Y2; and a third yaw sensing mass block Y3 and a fourth yaw sensing mass block Y4, forming a second pair of yaw sensing mass blocks Y3 and Y4. In a non-limiting embodiment, each yaw sensing mass block Y1, Y2, Y3, Y4 has a substantially quadrilateral shape in a plane, for example, a rectangle with a long side parallel to the X-axis.

[0051] Each yaw sensing mass in the first pair of yaw sensing mass blocks Y1, Y2 is coupled to a corresponding elastic element 38 (in Figure 1 and Figure 2In the example, the number of coupling elastic elements for each mass block is equal to two (between the end portions of the coupled drive mass block and the yaw sensing mass block) which are elastically coupled to the corresponding drive mass block in the first pair of drive mass blocks D1, D2. Similarly, each yaw sensing mass block in the second pair of yaw sensing mass blocks Y3, Y4 is elastically coupled to the corresponding drive mass block in the second pair of drive mass blocks D3, D4 via a corresponding coupling elastic element 38.

[0052] Furthermore, the first pair of yaw sensing mass blocks Y1, Y2 and the second pair of yaw sensing mass blocks Y3, Y4 are coupled to each other via corresponding elastic coupling structures 39. These elastic coupling structures 39 extend centrally to the MEMS structure 3 and along the X-axis, spanning the first axis of symmetry M1. Specifically, each elastic coupling structure 39 defines a centrally pivotal lever elastic element, hinged to the support body 2 via a yaw anchor 40, and coupled at its end to the corresponding yaw sensing mass block forming either the first pair of Y1, Y2 or the second pair of Y3, Y4.

[0053] The coupling element 38 and the elastic coupling structure 39 thus allow the yaw sensing masses Y1, Y2, Y3, Y4 to perform "in-plane" movement in the XY plane, specifically sensing movement along the Y-axis in response to rotation of device 1 about a rotation axis parallel to the Z-axis (e.g., ...). Figure 2 (As shown and described in more detail below). That is, the yaw sensing mass blocks Y1, Y2, Y3, and Y4 are used in device 1 to sense the yaw angular velocity.

[0054] For simplicity and not illustrated, yaw sensing mass blocks Y1, Y2, Y3, and Y4 have windows inside (in their respective sectors) for movable yaw sensing electrodes that are coupled to the same mass block (or in any case integrated with it) and alternate with corresponding fixed yaw sensing electrodes to define a differential yaw sensing scheme.

[0055] According to one aspect of the invention, the device 1 includes a multifunctional damping and stopping structure 5 associated with each yaw sensing mass Y1, Y2, Y3, Y4. As described in more detail below, each multifunctional structure 5 is configured to perform both damping along the Y-axis and stopping along the Y-axis and optionally also along the X-axis for the corresponding yaw sensing mass Y1, Y2, Y3, Y4.

[0056] Refer again Figure 1The driving mass blocks D1, D2, D3, and D4 of MEMS structure 3 are driven (through appropriate polarization of the movable driving electrode and the corresponding fixed driving electrode) to perform translational movements along the X-axis in opposite phase for each pair. Furthermore, the movements of the driving mass blocks of each pair that are symmetrical to each other with respect to the second axis of symmetry M2 (i.e., the movements of driving mass blocks D1, D3 and D2, D4) are also in opposite phase.

[0057] like Figure 1 As indicated by the arrows, the movement of the drive masses D1, D2, D3, and D4 results in corresponding movement of the sensing masses due to the aforementioned elastic coupling. Specifically, the roll sensing masses R1 and R2 rotate in the opposite phase in the XY plane about an axis parallel to the Z-axis and passing through the center of the corresponding roll anchor 36. Furthermore, the yaw sensing masses Y1, Y2, Y3, and Y4 are moved by their associated corresponding drive masses D1, D2, D3, and D4 in the same opposite phase translational movement along the X-axis. The movement of the drive masses D1, D2, D3, and D4 also causes the pitch sensing masses P1 and P2 to rotate in the opposite phase about an axis parallel to the Z-axis and passing through the center of the corresponding pitch anchor 34 due to the coupling elastic element 33 (whose operation is described in detail above).

[0058] The aforementioned driving movement therefore occurs entirely "in-plane" in the XY plane and does not involve other elements of the MEMS structure 3 of the gyroscope 1.

[0059] exist Figure 2The diagram schematically illustrates (via arrows) the unique sensing movements performed by the sensing mass blocks of MEMS structure 3 in the presence of corresponding angular velocities. Specifically, in the presence of a pitch angular velocity about the Y-axis, the sensing movement of MEMS structure 3 is an out-of-plane, anti-phase rotation of pitch sensing mass blocks P1 and P2 about a rotation axis parallel to the X-axis relative to the XY plane. In the presence of a roll angular velocity about the X-axis, the sensing movement of MEMS structure 3 is an out-of-plane, anti-phase rotation of roll sensing mass blocks R1 and R2 about a rotation axis parallel to the Y-axis relative to the XY plane. In the presence of a yaw angular velocity about the Z-axis, the sensing movement of MEMS structure 3 is an anti-phase displacement of each pair of yaw sensing mass blocks Y1, Y2, Y3, and Y4 along the Y-axis. Furthermore, the movements of each pair of yaw sensing mass blocks symmetrical to each other with respect to the second axis of symmetry M2 (i.e., the movements of yaw sensing mass blocks Y1, Y3 and Y2, Y4) are also anti-phase. These movements also cause the lever elastic element of the elastic coupling structure 39 to rotate in the XY plane about the corresponding yaw anchor 40, and the elastic coupling structure 39 couples the yaw sensing mass blocks symmetrical about the first axis of symmetry M1 to each other. As previously described, the movable yaw electrode (not shown in the figures) moves along the Y-axis relative to the corresponding fixed yaw electrode facing the movable yaw electrode, and the capacitance between the movable yaw electrode and the fixed yaw electrode changes accordingly.

[0060] In the MEMS structure 3 of device 1, it is advantageous that the sensing movements of the yaw sensing mass, roll sensing mass, and pitch sensing mass are completely independent of each other and do not affect each other at all. This effectively makes the interference between the sensing axes of gyroscope 1 (so-called cross-axis interference) essentially zero, or negligible in any case. Specifically, the drive masses D1-D4 essentially act as decoupling elements between the various sensing masses. Each sensing mass is in fact only connected to drive masses D1-D4, with virtually no interconnection (and interference), and is driven by the same drive masses D1-D4 in a single drive mode. Furthermore, the differential sensing scheme employed allows for the elimination of effects associated with both linear perturbation vibration and angular perturbation vibration.

[0061] Still referencing Figure 3The following describes one of the damping and stopping structures 5 of the device 1, such as the damping and stopping structure 5 associated with the fourth yaw sensing mass Y4; the same considerations apply to the other damping and stopping structures 5 and the associated yaw sensing masses Y1, Y2, Y3, while taking into account the symmetry of the MEMS structure 3 with respect to the first axis of symmetry M1 and the second axis of symmetry M2. Furthermore, for simplicity, the fourth yaw sensing mass Y4 associated with the discussed damping and stopping structure 5 will be simply referred to as the movable mass Y4. Additionally, in the following, referring only to the yaw sensing mass, the X-axis will also be referred to as the drive axis and its direction as the drive direction X, and the Y-axis will also be referred to as the sensing axis and its direction as the sensing direction Y. The drive masses D1, D2, D3, D4 thus act as actuators for the movable mass Y4, i.e., the drive masses D1, D2, D3, D4 are configured to keep the movable mass Y4 oscillating along the drive direction X.

[0062] As previously described, the movable mass Y4 is elastically constrained to the support 2 with a degree of freedom relative to the driving direction X and a degree of freedom relative to the sensing direction Y. The movable mass Y4 specifically includes a frame portion 6 defining a through opening 7, in which a damping and stop structure 5 is accommodated.

[0063] The movable mass block Y4 also includes a plurality of first elongated elements (or fingers) 65, defined by a plate perpendicular to the Y-axis, extending in a comb-like manner from the frame portion 6 toward the center of the opening 7, and having a large dimension parallel to the driving direction X. More specifically, Figure 3 The movable mass block Y4 comprises a plurality of first elongated elements 65, including a first group 651 and a second group 652 of the first elongated elements 65. The first elongated elements of the first group 651 extend from a first side 61 of the frame portion 6, while the first elongated elements of the second group 652 extend from a second side 62 of the frame portion 6 opposite to the first side 61 along the X-axis. In a non-limiting manner, each first elongated element of the first group 651 is aligned along the driving direction X with a corresponding first elongated element of the second group 652. Figure 3 In a non-limiting embodiment, the first elongated element of the first group 651 and the first elongated element of the second group 652 both have the same length along the X-axis.

[0064] The first elongated element 65 is thus rigidly fixed to the frame portion 6 of the movable mass block Y4, and follows the aforementioned drive and sensing movement during use of the device 1.

[0065] The damping and stop structure 5 is anchored to the support 2 (as well as...) Figure 1 and Figure 2(Illustratively shown) and is housed in the opening 7 of the movable mass Y4. In a non-limiting embodiment, the damping and stopping structure 5 includes a first anchor 51, a second anchor 52, a plurality of second elongated elements (or fingers) 55, and a plurality of stopping elements 56. As explained in more detail below, the damping and stopping structure 5 is static in use and separate from the movable mass Y4, contacting it only when the movable mass Y4 is stopped.

[0066] The first anchor 51 has an elongated shape parallel to the sensing direction Y, for example, it has a rectangular shape in a plane. The first anchor 51 is arranged between a first group 651 and a second group 652 of the first elongated elements 65 of the movable mass block Y4, and at a certain distance from the first group 651 and the second group 652 of the first elongated elements 65 of the movable mass block Y4. In one embodiment, the first anchor 51 is arranged in a substantially central position in the opening 7. Specifically, the first anchor 51 has a first side 511 arranged facing a first side 61 of the frame portion 6, and a second side 512 arranged facing a second side 62 of the frame portion 6. Furthermore, the first anchor 51 includes a base 513 through which the first anchor 51 is anchored to the support 2; as... Figure 3 As shown in a non-limiting embodiment, the base 513 has an extension (parallel to the XY plane) that is, for example, smaller than the remainder of the first anchor 51, which is therefore suspended, for example, relative to the support 2. In another embodiment (not shown), the base 513 instead has an extension equal to the entire extension of the first anchor 51.

[0067] In one embodiment, the second anchor 52 has an elongated shape parallel to the driving direction X, for example, it has a rectangular shape in a plane. The first anchor 51 and the second anchor 52 form, for example, a single body. The second anchor 52 of the damping and stopping structure 5 specifically includes two side arms 521 that extend from the first anchor 51 in a direction parallel to the X-axis. The first anchor 51 and the second anchor 52 thus form a "T"-shaped structure of the damping and stopping structure 5. More specifically, the second anchor 52 is arranged adjacent to and substantially parallel to the third side 63 of the frame portion 6 of the movable mass block Y4. The second anchor 52 and the third side 63 are substantially parallel to the X-axis. Furthermore, the total length of the second anchor 52 (along the X-axis) is comparable to the corresponding length of the third side 63 of the frame portion 6, which, as will become clearer below, improves the stopping action of the movable mass block Y4 operated by the damping and stopping structure 5. The second anchor 52 also includes a base 523, through which the second anchor 52 is anchored to the support 2; as Figure 3As shown in a non-limiting embodiment, base 523 has an extension (parallel to the XY plane) smaller than the remainder of the second anchor 52, which is therefore suspended, for example, relative to the support 2. In another embodiment (not shown), base 523 instead has an extension equal to the entire extension of the second anchor 52. Bases 513 and 523, for example, form a single body.

[0068] The second elongated element 55 is also defined by a plate perpendicular to the Y-axis, extending in a comb-like manner from the first anchor 51 toward the first side 61 and the second side 62 of the frame portion 6, and has a larger dimension parallel to the drive direction X. The plurality of second elongated elements 55 of the damping and stop structure 5 includes a first group 551 and a second group 552 of second elongated elements 55. The second elongated elements of the first group 551 extend in a direction opposite to the second elongated elements 55 of the second group 552. Specifically, the second elongated elements of the first group 551 extend from the first side 511 of the first anchor 51, while the second elongated elements of the second group 552 extend from the second side 512 of the first anchor 51. In a non-limiting manner, each second elongated element of the first group 551 is aligned along the drive direction X with a corresponding second elongated element of the second group 552. Figure 3 In a non-limiting embodiment, the second elongated elements of the first group 551 and the second elongated elements of the second group 552 both have the same length along the X-axis. Furthermore, the second elongated element 55, supported by the first anchor 51, can be provided to be completely suspended relative to the support 2.

[0069] The first elongated element 65 of the first group 651 and the second elongated element 55 of the first group 551 are interleaved. Similarly, the first elongated element 65 of the second group 652 and the second elongated element 55 of the second group 552 are interleaved. The first elongated element 65 and the second elongated element 55 facing each other are separated by a gap having a width greater than the stationary distance between the stop element 56 and the frame portion 6, so as to avoid contact between the first elongated element 65 and the second elongated element 55.

[0070] In the damping and stopping structure 5, the second anchor 52 (and specifically the two side arms 521) faces the first elongated element 65 and the second elongated element 55 on the opposite side to the third side 63 facing the frame portion 6. In other words, the first elongated element 65 and the second elongated element 55 are internally enclosed by the "T"-shaped structure of the damping and stopping structure 5. Figure 3 In a non-limiting embodiment, for example, the side arm 521 faces and is adjacent to the corresponding first elongated element 65 of the movable mass block Y4. Furthermore, also in a non-limiting manner, the side arm 521 has a length (along the X-axis) such that its corresponding projection along the Y-axis is flush with the free end of the second elongated element 55.

[0071] As anticipated by the first elongated element 65 of the movable mass Y4, the second elongated element 55 of the damping and stop structure 5 also has a length (along the X-axis) that does not mechanically interfere with the movement of the movable mass Y4. Specifically, the length of the second elongated element 55 allows sufficient clearance and permits driven movement of the movable mass Y4 in use without contact between the second elongated element 55 and the movable mass Y4. In other words, the corresponding free ends of the second elongated element 55 are located at a distance from the corresponding first side 61 and second side 62 of the frame portion 6. The overall shape of the damping and stop structure 5 of the present invention ensures proper driven movement of the MEMS structure 3.

[0072] The second elongated element 55, like the entire damping and stop structure 5, remains stationary during the use of the device 1. Furthermore, as previously described, the second elongated element 55 of the damping and stop structure 5 is arranged alternately with the first elongated element 65 of the movable mass Y4. According to one aspect of the invention, the first elongated element 65 of the movable mass Y4 and the second elongated element 55 of the damping and stop structure 5 form a viscous damper for the movable mass Y4 (i.e., for the yaw sensing mass Y4) along the sensing direction Y. Specifically, in the device 1 of the invention, the damping effect of the oscillation along the sensing direction Y is achieved by the viscous friction created by the gas mixture contained in the chamber (not shown) housing the gyroscope 1, due to the movement of the first elongated element 65 of the movable mass Y4 toward the second elongated element 55 of the damping and stop structure 5.

[0073] The stop element 56 of the damping and stop structure 5 is configured to limit the movement of the movable mass Y4 along the sensing direction Y, that is, to limit the sensing oscillation of the yaw sensing mass Y4. Specifically, the stop element 56 includes a corresponding contact portion (e.g., in the form of a "bumper") protruding toward the frame portion 6 of the movable mass Y4. More specifically, the plurality of stop elements 56 includes a first stop element 561 protruding from the first anchor 51. Figure 3 One is shown in the image) and a second stop element 562 protruding from the second anchor 52. Figure 3 (Six are shown in the diagram). The first stop element 561 protrudes toward the fourth side 64 of the frame portion 6 (opposite to the third side 63 along the Y-axis), while the second stop element 562 protrudes toward the third side 63 of the frame portion 6. The stop elements 56 are arranged and shaped to not impede the sensing movement of the movable mass block Y4 under the conditions of use of the device 1 where the sensing movement is kept within a range of a considered safe operating position. Furthermore, the first stop element 561 protrudes from the first anchor 51 toward the fourth side 64 of the frame portion 6 beyond the second elongated element 55 located externally and facing the fourth side 64 of the frame portion 6.

[0074] Now for reference Figure 4 The damping and stopping structures are described according to different embodiments of the invention and are indicated by reference numeral 105. The damping and stopping structure 105 and its associated movable mass block Y4 will be referred to below only with respect to... Figure 3 The differences between the damping and stopping structure 5 and the movable mass block Y4 are described below. Furthermore, the damping and stopping structure 105 differs from... Figure 3 The components of the damping and stop structure 5 are indicated by the same reference numerals, increased by 100. Figure 4 The movable mass block Y4 and Figure 3 The components corresponding to the movable mass block Y4 are indicated using the same reference numerals.

[0075] In detail, Figure 4 The movable mass block Y4 comprises a plurality of first elongated elements 65 including a single group of first elongated elements 65, the single group of first elongated elements 65 extending from the second side 62 of the frame portion 6 toward the center of the opening 7 in a manner similar to that described above.

[0076] The damping and stopping structure 105 includes a first anchor 151, a second anchor 152, a plurality of second elongated elements or fingers 155, and a plurality of stopping elements 156.

[0077] The first anchor 151 is similar in shape to Figure 3 The first anchor 51 of the damping and stopping structure 5 is arranged adjacent to and substantially parallel to the first side 61 of the frame portion 6 of the movable mass block Y4. Furthermore, the total length of the first anchor 151 (along the Y-axis) is comparable to the corresponding length of the first side 61 of the frame portion 6. The first anchor 151 specifically has a first side 611 arranged facing the first side 61 of the frame portion 6, and a second side 612 arranged facing the second side 62 of the frame portion 6. Finally, the first anchor 151 includes a base 613 through which the first anchor 151 is anchored to the support 2, the base 613 being capable of having an extension (in the XY plane) smaller than the entire extension of the first anchor 151.

[0078] The second anchor 152 is arranged adjacent to and substantially parallel to the third side 63 of the frame portion 6 of the movable mass block Y4. Furthermore, the total length of the second anchor 152 (along the X-axis) is comparable to the corresponding length of the third side 63 of the frame portion 6. Specifically, the second anchor 152 includes a single arm connected to one end of the first anchor 151 and extending along the X-axis only from a portion of the first anchor 151 (i.e., toward the second side 62 of the frame portion 6). The first anchor 151 and the second anchor 152 thus form an "L"-shaped structure of the damping and stopping structure 105. Figure 4 (The middle is the reverse). Finally, the second anchor 152 includes a base 623 through which the second anchor 152 is anchored to the support 2, and the base 623 is capable of having an extension smaller than the entire extension of the second anchor 152 (in the XY plane).

[0079] The damping and stopping structure 105 comprises a plurality of second elongated elements 155, each group of which extends from the second side 612 of the first anchor 151 toward the center of the opening 7 and thus toward the second side 62 of the frame portion 6. The second elongated elements 155 are arranged alternately with the first elongated elements 65 of the movable mass block Y4.

[0080] The stop element 156 of the damping and stop structure 105 is configured to limit not only the movement of the movable mass Y4 along the sensing direction Y, but also the movement of the movable mass Y4 along the driving direction X. Specifically, the plurality of stop elements 156 includes: a first stop element 661 ( Figure 4 Three are shown in the figure), which protrude from the first anchor 151 toward the first side 61 of the frame portion 6; the second stop element 662 ( Figure 4 Two are shown in the figure), which protrude from the second anchor 152 toward the third side 63 of the frame portion 6; and optionally also includes a third stop element 663 ( Figure 4 One is shown in the diagram, which protrudes from the first anchor 151 toward the fourth side 64 of the frame portion 6. More specifically, the second stop element 662 and the third stop element 663 are configured to limit the movement of the movable mass block Y4 along the sensing direction Y, while the first stop element 661 is configured to limit the movement of the movable mass block Y4 along the driving direction X. The third stop element 663 of the damping and stop structure 105 is actually similar to Figure 3 The first stop element 561 of the damping and stopping structure 5.

[0081] The damping and stopping structure of the present invention thus allows for the advantageous integration of both damping and stopping actions of its associated movable mass block along the same direction (the sensing direction in the illustrated example) in a compact and space-constrained single solution. Specifically, the damping and stopping structure combines the stator portion of a viscous damper with a stopping element at least for the sensing direction. More specifically, in the damping and stopping structure of the present invention, the first and second anchors can be provided with dimensions comparable to the dimensions of the side surfaces of the frame portion of the adjacent movable mass block, thereby effectively achieving an advantageously wider stopping area. Furthermore, the shapes of the aforementioned damping and stopping structures (“T-shaped” and “L-shaped”) allow for the development of the maximum possible anchoring area to the support. Ultimately, the damping and stopping structure of the present invention allows for improved mechanical robustness of MEMS devices to shocks and, combined with a reduction in the quality factor Q along the sensing direction, improves the vibration immunity of the device.

[0082] More specifically, the damping and stopping structure of the present invention provides the possibility of a design trade-off between the damping and stopping requirements of a movable mass block. For example, Figure 3 The damping and stopping structure 5 allows for a high damping area, achieving a symmetrical and dual damping structure relative to the first anchor 51. Figure 4 The damping and stopping structure 105 has been modified to allow for greater priority to the stopping action, while maintaining a more compact damping area (single damping structure) and introducing a stopping action along the driving direction X.

[0083] As can be understood from the above, the association of the damping and stop structure with the movable mass (such as the movable mass of gyroscope 1) is merely an illustrative embodiment. The damping and stop structure of the present invention can actually be used in any other MEMS device, any other MEMS device including one or more movable mass blocks having a frame portion capable of accommodating the same damping and stop structure and having a relative degree of freedom with respect to even only one direction of motion (whether the sensing direction or the driving direction).

[0084] Finally, it will be apparent that modifications and variations may be made to the description and illustrations herein without departing from the scope of the invention as defined by the appended claims.

[0085] For example, damping and stop structures may not be associated with all pitch sensing mass blocks, but only with one pitch sensing mass block in each pair of pitch sensing mass blocks.

[0086] The “T-shaped” damping and stop structure can, for example, be asymmetrical relative to the first anchor, i.e., the first anchor can be arranged in an eccentric position in the opening, and thus the second elongated elements of different groups can have different lengths from each other. Furthermore, the second elongated elements of the first group can be misaligned relative to the second elongated elements of the second group; similarly, the first elongated elements of the first group can be misaligned relative to the first elongated elements of the second group.

[0087] In embodiments not shown, the damping and stop structure may have an axisymmetric shape about the X-axis and passing through the center of the damping and stop structure. In such cases, the damping and stop structure includes an additional second anchor, which is opposite to the aforementioned second anchor and similar in shape and function. For example, a damping and stop structure may be provided in which the first and second anchors form an "H-shape" structure, or in which the first and second anchors form a "C-shape" structure.

[0088] In other embodiments not shown, in conjunction with Figure 3 In a damping and stopping structure similar to the previous one, the first anchor includes separate first anchor portions aligned along the Y-axis and each anchored to a support. Corresponding second elongated elements from the first and second groups extend from each of the first anchor portions. Such variations can also be applied to... Figure 4 The damping and stopping structures are similar to those of other damping and stopping structures.

[0089] As long as the stopping function can be achieved in at least one direction of movement of the movable mass block, the stopping element can be different from the shape of the buffer described and shown.

Claims

1. A microelectromechanical device, comprising: Support structure; A movable mass block, the movable mass block being constrained to the support with a relative degree of freedom with respect to at least a first direction parallel to the support, and including a frame portion defining an opening; as well as A damping and stopping structure is anchored to the support and accommodated within the opening of the movable mass block. The movable mass block includes a first elongated element defined by a corresponding plate perpendicular to the first direction, and extends from the frame portion into the opening in a comb-like configuration. The damping and stopping structure includes a second elongated element anchored to the support body, defined by a corresponding plate perpendicular to the first direction, and extending in a comb-like configuration toward the frame portion of the movable mass block. The second elongated element intersects with the first elongated element. The damping and stopping structure further includes a stopping element configured to restrict movement of the movable mass block along at least the first direction.

2. The device of claim 1, wherein the first elongated element is rigidly fixed to the movable mass block, and wherein the first elongated element and the second elongated element form a viscous damper for the movable mass block along the first direction.

3. The device of claim 1, wherein the device is a gyroscope, and the movable mass has another degree of freedom relative to a second direction, the second direction being parallel to the support and perpendicular to the first direction. The device further includes an actuator configured to maintain the movable mass block oscillating along the second direction, and The movable mass block is constrained to the support to oscillate along the first direction in response to rotation about a rotation axis perpendicular to the support.

4. The device of claim 1, wherein the stop element of the damping and stop structure includes a contact portion that protrudes toward the frame portion of the movable mass block.

5. The device of claim 1, wherein the damping and stopping structure includes a first anchor of an elongated shape, the first anchor being parallel to the first direction, and the second elongated element being supported by the first anchor.

6. The device of claim 5, wherein the damping and stopping structure further comprises an elongated second anchor, the second anchor being parallel to a second direction, the second direction being parallel to the support and perpendicular to the first direction.

7. The device of claim 6, wherein the stopping element of the damping and stopping structure protrudes from a respective anchor of the first anchor and the second anchor toward the frame portion of the movable mass block.

8. The device according to claim 6, wherein the first anchor and the second anchor form a single body.

9. The device of claim 6, wherein the first anchor of the damping and stopping structure extends substantially parallel to a first side of the frame portion of the movable mass block, the first sides being opposite each other along the second direction, and wherein the second anchor extends substantially parallel to a second side of the frame portion, the second sides being opposite each other along the first direction.

10. The device of claim 9, wherein the first elongated element of the movable mass block comprises a first group of first elongated elements and a second group of first elongated elements, wherein the first elongated elements of the first group and the first elongated elements of the second group extend from respective first sides of the frame portion. The first anchor of the damping and stopping structure is arranged between the first group of the first elongated elements and the second group of the first elongated elements, and at a certain distance from the first group of the first elongated elements and the second group of the first elongated elements. The second elongated element of the damping and stopping structure includes a first group of second elongated elements and a second group of second elongated elements, wherein the second elongated elements of the first group and the second elongated elements of the second group extend from corresponding opposite sides of the first anchor along the second direction, and The second elongated element of the first group is interleaved with the first elongated element of the first group, and the second elongated element of the second group is interleaved with the first elongated element of the second group.

11. The device of claim 10, wherein each first elongated element of the first group is aligned with a corresponding first elongated element of the second group along the second direction, and wherein each second elongated element of the first group is aligned with a corresponding second elongated element of the second group along the second direction.

12. The device of claim 10, wherein the first anchor is disposed substantially centrally in the opening of the movable mass block, and wherein the second anchor comprises two arms extending from opposite sides relative to the end of the first anchor, and the second anchor is disposed on one of the second sides of the frame portion of the movable mass block.

13. The device of claim 10, wherein the stop element comprises a first stop element and a second stop element, the first stop element protruding from the first anchor, the second stop element protruding from the second anchor, and the second stop element and the first stop element protruding toward a respective second side of the frame portion.

14. The device of claim 9, wherein the first elongated element of the movable mass block extends from one of the first sides of the frame portion. The second elongated element of the damping and stopping structure extends from one of the first sides of the first anchor facing the frame portion. The first anchor is arranged on another first side adjacent to the first side of the frame portion, and The second anchor is arranged on one of the second sides adjacent to the frame portion.

15. The device of claim 14, wherein the stop element comprises a first stop element and a second stop element, the first stop element projecting from the first anchor toward the other first side of the first side of the frame portion, the second stop element projecting from the second anchor toward the one second side of the second side of the frame portion, the first stop element being configured to restrict movement of the movable mass block along the second direction, and the second stop element being configured to restrict movement of the movable mass block along the first direction.

16. A method of operating a microelectromechanical device (MEMS), the MEMS comprising a support, a movable mass, and a damping and stopping structure, the movable mass being constrained to the support with a degree of freedom along a first direction, the damping and stopping structure being anchored to the support and received in an opening in the movable mass, the method comprising: The movable mass block is made to oscillate along the first direction; The oscillation of the movable mass block along the first direction is damped by providing viscous friction between the staggered first elongated element fixed to the movable mass block and the second elongated element anchored to the support. When the displacement of the movable mass block along the first direction exceeds a predetermined range, the displacement of the movable mass block along the first direction is limited by bringing the stop element of the damping and stop structure into contact with the movable mass block.

17. The method of claim 16, further comprising: An actuator is used to drive the movable mass block to oscillate in a controlled manner along a second direction, which is perpendicular to the first direction; In response to the rotation of the support body about an axis perpendicular to the support body, a physical quantity is sensed by detecting the oscillation of the movable mass block along the first direction.

18. The method of claim 16, wherein the damping and stopping structure comprises a first anchor and a second anchor, the first anchor extending parallel to the first direction, the second anchor extending parallel to a second direction, the second direction being perpendicular to the first direction; and The method further includes: The second elongated element is anchored to the first anchor, and a stop element protruding from at least one of the first and second anchors toward the movable mass block is provided.

19. The method of claim 16, further comprising: By providing a stop element that protrudes from the damping and stop structure toward a corresponding side of the movable mass, the stop element is configured to restrict movement of the movable mass along both the first direction and the second direction, the second direction being perpendicular to the first direction.

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