Common mode rejection structure for MEMS device

Abstract

A MEMS device, and a method of forming the MEMS device, includes a pair of masses suspended above a substrate, including a link coupling the pair of masses to each other. Inner sensing links couple the inner edges of adjacent masses to each other. The internal sensing links are configured to exhibit a first stiffness when the adjacent masses coupled to each internal sensing link move out of phase relative to each other along a preferred axis of the internal sensing link, and exhibit a second increased stiffness in response to in-phase movement of the adjacent masses coupled to each internal sensing link.

Description

Technical Field

[0001] Embodiments of the subject matter described herein relate to microelectromechanical systems (MEMS) rotation rate sensors. Background Art

[0002] One method of angular rate sensing in a microelectromechanical system (MEMS) involves oscillating a proof mass coupled to a substrate by one or more springs along a selected axis. When the substrate (along with the proof mass) undergoes rotation, the motion of the proof mass will deviate from a straight-line path due to significant Coriolis forces in a direction perpendicular to the axis of oscillation of the proof mass. This deflection of the proof mass may cause a change in the capacitance of a circuit used to convert the motion of the proof mass into an electrical signal.

[0003] The reliability, accuracy, and sensitivity of such MEMS rotation sensors can be improved by coupling multiple proof masses together and driving them so that they oscillate in opposite directions along a common axis (commonly referred to as "out-of-phase" or "anti-phase" motion). This arrangement can be used in a circuit that measures the change in differential capacitance between a proof mass and a suitably configured sensing electrode. When the proof masses driven out of phase experience the same rotation, they will similarly experience out-of-phase shifts in a direction perpendicular to the axis of oscillation. At the same time, if both proof masses are subjected to an external force rather than rotating about the desired axis of rotation, the proof masses will move together and (ideally) no change in the differential capacitance signal will be measured. Summary of the invention

[0004] In an example embodiment, a MEMS device includes a substrate, and includes a first, second, third, and fourth mass suspended above the substrate. The first mass is adjacent to the second mass and the third mass. The second mass is adjacent to the first mass and the fourth mass. The third mass is adjacent to the first mass and the fourth mass. The first inner sense link is disposed between the first mass and the third mass and is coupled to the first mass and the third mass. The second inner sense link is disposed between the second mass and the fourth mass and is coupled to the second mass and the fourth mass. Each inner sense link includes an upper portion, a lower portion, and a central torsional bend. The central torsional bend has a first end coupled to the upper portion of the inner sense link and a second end coupled to the lower portion of the inner sense link. The first torsion spring is coupled between the upper portion of the inner sense link and the lower portion of the inner sense link. The middle portion of the inner sense link is coupled to the central torsional bend at a position between the first end of the central torsional bend and the second end of the central torsional bend. The first torsion spring is configured to exhibit an increase in stiffness when the upper and lower portions of the inner sense link move in phase with each other along an axis parallel to the central torsional bend and the upper and lower portions of the inner sense link are displaced a predetermined distance.

[0005] In another example embodiment, a method of forming a first, second, third, and fourth mass suspended above a substrate. The first mass is adjacent to the second mass and the third mass. The second mass is adjacent to the first mass and the fourth mass. The third mass is adjacent to the first mass and the fourth mass. The method also includes forming a first inner sensing link and a second inner sensing link. The first inner sensing link is disposed between the first mass and the third mass and is coupled to the first mass and the third mass. The second inner sensing link is disposed between the second mass and the fourth mass and is coupled to the second mass and the fourth mass. Each inner sensing link includes an upper portion, a lower portion, and a central torsional bend. The central torsional bend has a first end coupled to the upper portion of the inner sensing link and a second end coupled to the lower portion of the inner sensing link. A first torsion spring is coupled between the upper portion of the inner sensing link and the lower portion of the inner sensing link. An intermediate portion of the inner sensing link is coupled to the central torsional bend at a position between the first end of the central torsional bend and the second end of the central torsional bend. The first torsion spring is configured to exhibit an increase in stiffness when the upper and lower portions of the inner sense link move in phase with each other along an axis parallel to the central torsional bend and the upper and lower portions of the inner sense link are displaced a predetermined distance.

[0006] In one or more embodiments, when the upper portion and the lower portion of the internal sensing link move in phase with each other along the axis parallel to the central torsional bend and the upper portion and the lower portion of the internal sensing link are displaced a predetermined distance, the first torsion spring is configured to impact one or both of the upper portion of the internal sensing link and the lower portion of the internal sensing link.

[0007] In one or more embodiments, each internal sensing link also includes: a second torsion spring, which is connected between the upper part of the internal sensing link and the lower part of the internal sensing link and is opposite to the first torsion spring; and the internal sensing link has a middle part, which is connected to the central torsion bend at a position between the first end of the central torsion bend and the second end of the central torsion bend; wherein when the upper part and the lower part of the internal sensing link move in phase with each other along an axis parallel to the central torsion bend and the upper part and the lower part of the internal sensing link are displaced a predetermined distance, the second torsion spring is configured to impact one or both of the upper part of the internal sensing link and the lower part of the internal sensing link.

[0008] In one or more embodiments, each internal sensing link further comprises: a first transverse bend oriented perpendicularly to the central torsional bend, the first transverse bend connecting the first end of the central torsional bend to a mass block corresponding to the upper portion of the internal sensing link; and a second transverse torsional bend oriented perpendicularly to the central torsional bend, the second transverse torsional bend connecting the second end of the central torsional bend to a mass block corresponding to the lower portion of the internal sensing link; wherein each transverse bend has a first and a second arm comprising corresponding folding springs; wherein the middle portion of each folding spring of the first transverse bend is connected to the first end of the central torsional bend, and the outer portion of each folding spring of the first transverse bend is connected to the mass block corresponding to the upper portion of the internal sensing link; and wherein the middle portion of each folding spring of the second transverse bend is connected to the second end of the central torsional bend, and the outer portion of each folding spring of the second transverse bend is connected to the mass block corresponding to the lower portion of the internal sensing link.

[0009] In one or more embodiments, it also includes: forming a first external sensing link, which is connected to the second outer edge of the first mass block and the second mass block; and forming a second external sensing link, which is opposite to the first external sensing link and connected to the second outer edge of the third mass block and the fourth mass block; wherein each external sensing link includes: a central part, which is anchored to the substrate via an anchor, and the anchor is surrounded by the central part; a first external part, which has a distal part anchored to the substrate and a proximal end connected to the central part via a first spring element; and a second external part, which has a distal part anchored to the substrate and a proximal end connected to the central part via a second spring element.

[0010] In one or more embodiments, the first external portion of the first external sensing link is connected to the first mass block via the first spring element of the first external sensing link, and the second external portion of the first external sensing link is connected to the second mass block via the second spring element of the first external sensing link; wherein the first external sensing link is configured to exhibit a first stiffness value in response to out-of-phase movement of the first mass block relative to the second mass block; and wherein the first external sensing link is configured to exhibit a second stiffness value greater than the first stiffness value in response to in-phase movement of the first mass block relative to the second mass block.

[0011] In one or more embodiments, the first external portion of the second external sensing link is connected to the third mass block via the first spring element of the second external sensing link, and the second external portion of the second external sensing link is connected to the fourth mass block via the second spring element of the second external sensing link; wherein the second external sensing link is configured to exhibit a third stiffness value in response to out-of-phase movement of the third mass block relative to the fourth mass block; and wherein the second external sensing link is configured to exhibit a fourth stiffness value greater than the third stiffness value in response to in-phase movement of the third mass block relative to the fourth mass block.

[0012] In one or more embodiments, the second stiffness value is at least 4 times greater than the first stiffness value. In one or more embodiments, the fourth stiffness value is at least 4 times greater than the third stiffness value. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present disclosure is illustrated by means of examples, embodiments, etc., and is not limited by the accompanying drawings, in which like reference numerals indicate similar elements. The elements in the drawings are shown for simplicity and clarity and are not necessarily drawn to scale. The drawings, together with the detailed description, are incorporated into and form part of the specification and serve to further illustrate examples, embodiments, etc. and to explain various principles and advantages according to the present disclosure, in which:

[0014] Figure 1 is a plan view of a MEMS device suitable for use in a rotation rate sensor according to one or more embodiments.

[0015] Figure 2 yes Figure 1 Detailed floor plan of the installation.

[0016] Figure 3 is shown in two different configurations Figure 1 and Figure 2 A plan view of additional detail of the internal sensing linkage of the device.

[0017] Figure 4 It is shown Figure 1 and Figure 2 A plan view of additional detail of the external sensing linkage of the device.

[0018] Figure 5 Depicted are simulation results comparing the performance of an external sensing linkage according to embodiments herein to the performance of another external sensing linkage. DETAILED DESCRIPTION

[0019] The following detailed description provides examples for the purpose of understanding and is not intended to limit the invention or the application and use of the invention. In addition, it is not intended to be bound by any explicit or implicit theory present in the foregoing technical field, background technology or the following detailed description.

[0020] For simplicity and clarity of illustration, the drawings illustrate general constructions, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the present invention. In addition, the elements in the drawings are not necessarily drawn to scale. For example, the dimensions of some elements or regions in the drawings may be enlarged relative to other elements or regions to help improve understanding of the embodiments of the present invention.

[0021] The terms "first", "second", "third", "fourth", etc. (if any) in the embodiments and claims can be used to distinguish similar elements and are not necessarily used to describe a specific sequence or time order. It should be understood that the terms used in this way are interchangeable where appropriate, so that the embodiments of the invention described herein can, for example, operate in a sequence other than the sequence shown or otherwise described herein. In addition, the terms "comprise / include", "having" and any variations thereof are intended to cover non-exclusive inclusions, so that a process, method, article or device including a series of elements is not necessarily limited to those elements, but may include other elements that are not explicitly listed or inherent to such processes, methods, articles or devices. The term "connection" as used herein is defined as being connected directly or indirectly in an electrical or non-electrical manner. As used herein, the terms "substantially" and "substantially" mean sufficient to achieve the stated purpose in a practical manner, and minor defects (if any) are not significant for the stated purpose.

[0022] Unless otherwise stated, directional references such as "top", "bottom", "left", "right", "above", "below", etc. are not intended to require any preferred orientation, and for illustrative purposes are made with reference to the orientation of the corresponding figure or figures or with reference to any other suitable orientation or axis.

[0023] It should be understood that the steps of the various processes described herein are non-limiting examples of suitable processes according to embodiments and are used for illustration purposes. Systems and devices according to embodiments herein may use any suitable process, including processes that omit the steps described above, processes that perform those steps and similar steps in a different order, etc. It should also be understood that well-known features may be omitted for clarity.

[0024] Embodiments described herein provide a MEMS rotation sensor in which proof masses are coupled to one another using a coupling structure configured to exhibit high stiffness in response to undesired common-mode ("in-phase") motion of adjacent proof masses while exhibiting low stiffness in response to desired out-of-phase motion of the proof masses. The stiffness of the structures disclosed herein can be characterized in units of force per unit distance (e.g., Newtons per meter, pounds per inch, etc.) and measured using known measurement techniques.

[0025] Figure 1 A schematic plan view of a MEMS device according to one or more embodiments is shown, which can be used as part of a rotation rate sensor (i.e., a MEMS gyroscope). Device 100 includes four proof masses (masses 110; i.e., masses 110(1), 110(2), 110(3), and 110(4) formed on substrate 102). Masses 110 are coupled to each other, to drive links 120, to external sense links 130, and to internal sense links 135 as shown. The internal drive links are schematically represented by springs 125, and features of such internal drive links can be seen in FIG. Figure 2 Seen in detail in (see inner drive link 225).

[0026] The drive links 120(1) and 120(2) (along with the internal drive link 125) can be actuated to drive the four proof masses 110 in an out-of-phase manner along the drive shaft axis (X), wherein each proof mass moves out of phase with the immediately adjacent proof mass. The arrows on each proof mass 110 indicate the relative direction of movement of the proof mass. For example, when the proof mass 110(1) moves in the -X direction, the proof mass 110(2) moves in the +X direction, and vice versa. Similarly, when the proof mass 110(3) moves in the -X direction, the proof mass 110(4) moves in the +X direction, and vice versa. The same out-of-phase relationship is maintained between the proof masses 110(1) and 110(3) and between the proof masses 110(2) and 110(4). When the device 100 undergoes a rotation about the Z axis (perpendicular to the Figure 1 When the proof masses 110 are rotated about the plane of rotation (i.e., the rotation of the proof masses 110), they will experience out-of-phase displacements along the sensing axis Y, which can be sensed using any suitable method, including capacitance measurements that are sensitive to the displacement of each mass 110. Therefore, it is desirable that various components of the rotation rate sensor, such as the device 100, resist in-phase motion of the mass 110 along the sensing axis Y, because they will generate spurious signals that are unrelated to the desired measurand (rotation about the axis Z).

[0027] exist Figure 1In the example of FIG. 1 , the motion of mass 110 along sense axis Y is constrained by outer sense link 130 and inner sense link 135. Masses 110(1) and 110(2) are coupled to each other and to outer sense link 130(1). Similarly, masses 110(3) and 110(4) are coupled to each other and to outer sense link 130(2). Masses 110(1) and 110(3) are coupled to each other via inner sense link 135(1), and masses 110(2) and 110(4) are coupled to each other via inner sense link 135(2).

[0028] The following will refer to Figures 3 to 4 To explain further, an external sense link such as external sense link 130 and / or an internal sense link such as internal sense link 135 according to embodiments of the present invention may exhibit greater stiffness in response to undesired in-phase motion of adjacent proof mass blocks along the sense direction Y as compared to the stiffness of these structures in response to out-of-phase motion of adjacent proof mass blocks.

[0029] It should be understood that various links or couplings may be schematically represented by springs or other structures for illustrative purposes, and any suitable structure may be used with the embodiments herein.

[0030] Figure 2 is an example device (e.g., Figure 1 Detailed plan view of device 100 of FIG. 100 is shown. Device 200 has four proof masses (mass 210, such as mass 110), a pair of drive links 220 (such as drive links 120), a pair of outer sense links 230 (such as outer sense links 130), and a pair of inner sense links 235 (such as inner sense links 135) coupled to one another. Proof masses such as mass 210 may have any suitable configuration. Figure 2 In the example of , each of the masses 210 is characterized by a central annular region suspended above the electrode array. When the mass 210 is translated along the sensing direction Y, the area of ​​the mass 210 above the corresponding electrode area changes, and there is a corresponding capacitance change between the mass 210 and the electrode array. This capacitance change can be converted into an electrical signal and processed using known techniques to generate a signal corresponding to the rotation experienced by the device 200.

[0031] Figure 3335 (e.g., inner sense link 135 or inner sense link 235) that forms part of a MEMS device in one or more embodiments. The inner sense link 335 has an upper portion 335A and a lower portion 335B. Each portion of the inner sense link 335 is configured to be coupled to a proof mass (e.g., mass 110 or mass 210). The upper portion 335A and the lower portion 335B of the inner sense link 335 are joined by a central torsional bend 336 that defines a central axis of the inner sense link 335. Two torsion springs 337 (torsion spring 337A and torsion spring 337B) extend from either side of a middle portion of the central torsional bend 336. In this example, the torsion spring 337 is a serpentine spring having ends coupled to the upper portion 335A and the lower portion 335B of the inner sense link 335 and a central portion extending away from the central torsional bend 336 .

[0032] The first transverse bend 338A is oriented perpendicular to the central torsional bend 336 and extends from a first end of the central torsional bend 336. The first transverse bend 338A couples the central torsional bend 336 to a mass corresponding to the upper portion 335A of the inner sense link 335 (e.g., as shown in FIG. 1 ) via two arms. Figure 2 Each arm includes a folded spring 339 having a first end coupled to a first end of the central torsional bend 336 and coupled to a mass 310A (e.g., one of the masses 110, 210, Figure 3 For simplicity, the portion of the inner sensing link 335 that couples the folding spring 339 to the mass 310A is schematically depicted as a simple spring (see FIG. Figure 2 Spring 236 depicted in FIG.

[0033] Similar to the first transverse bend 338A, the second transverse bend 338B is oriented perpendicular to the central torsional bend 336 and extends from a second end of the central torsional bend 336. The second transverse bend 338B couples the central torsional bend 336 to a mass corresponding to the lower portion 335B of the inner sense link 335 (e.g., as shown in FIG. 1 ) via two arms. Figure 2 Each arm includes a folded spring 339 having a first end coupled to a second end of the central torsional bend 336 and coupled to a mass 310B (e.g., one of the masses 110, 210, Figure 3For simplicity, the portion of the inner sensing link 335 that couples the folding spring 339 to the mass 310B is schematically depicted as a simple spring (see FIG. Figure 2 Spring 236 depicted in FIG.

[0034] The first and second transverse flexures 338A, 338B are coupled to the central torsional flexure 336 via a crossbar 340. In general, the first and second transverse flexures 338A, 338B are configured to decouple the motion of the mass coupled to each inner sense link 335 along the drive axis (X) from its motion along the sense axis (Y). That is, the crossbar 340 is configured to relieve stresses that would otherwise be generated if the central torsional flexure 336 were rigidly coupled to the upper and lower portions 335A, 335B. This arrangement allows the inner sense links 335 to deform in response to out-of-phase motion of the upper and lower portions 335A, 335B of the inner sense links 335 (due to motion of the masses coupled to those portions) without inducing excessive stresses in the central torsional flexure 336 that could cause mechanical failure of the central torsional flexure 336.

[0035] As shown in the inset indicated by arrow 399, the torsion spring 337 is configured such that when the upper portion 335A of the inner sense link 335 is displaced in the same direction as the lower portion 335B (i.e., when the mass 310A coupled to the upper portion 335A undergoes an in-phase displacement in the sensing direction relative to the mass 310B coupled to the lower portion 335B), the torsion spring 337 may strike either the upper portion 335A of the inner sense link 335 or the lower portion 335B of the inner sense link 335 as shown. Thus, when the upper portion 335A and the lower portion 335B move in phase with each other, the effective stiffness of the inner sense link 335 increases, and in one or more embodiments, if the displacement of the mass coupled to the link exceeds a predetermined limit, the stiffness is further increased such that one or both torsion springs 337 strike either the upper portion 335A or the lower portion 335B of the inner sense link 335.

[0036] It should be appreciated that features of a link (e.g., inner sense link 335) according to embodiments herein can provide an apparatus, such as apparatus 100 or apparatus 200, with improved resistance to undesired in-phase motion of structures of proof masses (e.g., masses 110, 210), such as used in a MEMS-based rotation sensor. In one or more embodiments, an inner sense link (e.g., inner sense link 135, 235, or 335) coupled to two masses (e.g., masses 110, 210) exhibits at least four times the stiffness it exhibits in response to out-of-phase motion of the masses. In one or more such embodiments, the stiffness of the inner sense link in response to in-phase motion of the masses is between four and twelve times the stiffness it exhibits in response to out-of-phase motion of the masses. In one or more other embodiments, such an inner sense link exhibits twelve times greater stiffness in response to in-phase motion of the masses than in response to out-of-phase motion of the masses. It should be further appreciated that when an internal sensing link, such as internal sensing link 335, is coupled to a proof mass and as Figure 1 and Figure 2 When arranged as depicted in FIG. 1 , the internal sensing link will be used to move the mass, such as mass 110, 210, along the drive direction (in Figures 1 to 5 The movement of the axis X in the sensing direction (in Figures 1 to 5 Furthermore, the stiffness exhibited by the inner sense links in response to in-phase motion of adjacent masses coupled to each inner sense link in the sense direction will be greater than the stiffness exhibited in response to out-of-phase motion of adjacent masses coupled to the same inner sense link along the sense direction.

[0037] Figure 4 An external sense link 430 (e.g., external sense link 130 or external sense link 230) is shown that forms part of a MEMS device in one or more embodiments. External sense link 430 has a central portion 431 coupled between two outer portions 435 (outer portions 435A, 435B). Each portion of external sense link 430 is coupled to a substrate (not shown), such as substrate 102, by a corresponding anchor. It should be understood that the arrangement of the various portions and corresponding anchors of external sense link 430 can impart various advantages as further described below.

[0038] The central portion 431 of the outer sensing link 430 is coupled to the substrate by an anchor 432 disposed within the footprint of the central portion 431 and extending within a hole in the central portion 431. In one or more embodiments, an anchor, such as anchor 432, can be disposed at a location that overlaps or otherwise coincides with the center of mass of a link, such as the outer sensing link 430.

[0039] Each outer portion 435 (i.e., outer portions 435A, 435B) of the outer sensing link 430 has an end proximal to the center portion 431 and coupled to the center portion 431 by a corresponding spring or other suitable link (i.e., springs 434A, 434B couple the respective outer portions 435A, 435B to the center portion 431). The respective distal ends of the outer portions 435 are coupled to the substrate by corresponding anchors 436 (i.e., anchors 436A, 436B couple the respective outer portions 435A, 435B to the substrate). As shown, the anchors 436A, 436B are disposed within the footprint of the respective outer portions 435A, 435B.

[0040] The central portion 431 and the outer portion 435 of the outer sensing link 430 are coupled to corresponding anchors using any suitably flexible link that allows the portions to move relative to each other. Thus, the central portion 431 is configured to pivot about the anchor 432, and the outer portion 435 is configured to pivot about its corresponding anchor 436. However, the movement of the various portions of the outer sensing link 430 is constrained because they are connected together by the springs 434A, 434B.

[0041] The mass of the outer sense link 430, along with the placement of the spring and anchor of the outer sense link 430, is configured such that the outer sense link 430 exhibits greater stiffness in response to in-phase motion of the outer portion 435 than in response to out-of-phase motion. Thus, in one or more embodiments, the outer portion of the link (e.g., outer portion 435), for example, of the outer sense link 430, is coupled to an adjacent proof mass in a MEMS device suitable for use in a rotation sensor (e.g., as the outer sense link 130 of the device 100, or as the outer sense link 230 of the device 200).

[0042] For example, when the first mass 410A is coupled to the outer portion 435A via spring 434A and the second mass 410B is coupled to the outer portion 435B via spring 434B as shown, the outer sense link 430 will tend to resist the in-phase movement of the masses 410A, 410B. This is because the central portion 431 of the outer sense link 430 is configured to pivot about the anchor 432, while the outer portions 435A, 435B are configured to pivot about the respective anchors 436A, 436B. If the masses 410A, 410B translate in the same direction (same amount) along the sense axis 'Y', the central portion 431 will not significantly pivot or bend, while the end of the outer portion 435 near the central portion 431 will bend away from the central portion 431, causing the spring 434 to extend and apply a restoring force that resists the displacement of the masses 410A, 410B and the stiffness of the outer portions 435A, 435B. At the same time, if the masses 410A, 410B move in opposite directions, the central portion 431 will bend about the anchor 432 and the proximal end of each outer portion 435 will bend along with the movement of the central portion 431, thereby reducing the extension of each spring 434 compared to the extension of each spring 434 when the masses are displaced in the same direction (thereby reducing the restoring force applied by the spring 434 that is opposite to the displacement of the masses 410A, 410B and the bending of the central portion 431 and the outer portion 435 of the external sensing link 430).

[0043] Additionally, the central placement of the anchor 432 within the footprint of the central portion 431 of the external sensing link 430, and the coupling between the central portion 431 and the external portion 435 anchored at its distal end, produces a structure that exhibits high stiffness under forces applied along the ‘X-axis.’ Thus, when compared to structures used for similar purposes that have anchors placed further away from the center of mass (typically outside the footprint of the structure) and that include only a single segment similar to the central portion 431 of the external sensing link 430, the external sensing link 430 will exhibit improved resistance to undesired movement along the ‘Y’ axis caused by forces directed along the ‘X’ axis.

[0044] In one or more embodiments, an external sense link (e.g., external sense link 130, 230, or 430) coupled to two masses (e.g., masses 110, 210) exhibits at least four times the stiffness in response to in-phase motion of the masses than it exhibits in response to out-of-phase motion of the masses. In one or more such embodiments, the stiffness of the external sense link in response to in-phase motion of the masses is between four and twelve times the stiffness in response to out-of-phase motion of the masses. In one or more other embodiments, such an external sense link exhibits twelve times greater stiffness in response to in-phase motion of the masses than it exhibits in response to out-of-phase motion of the masses.

[0045] In some previous approaches utilizing four masses (eg, masses 110 or 210), each mass is coupled to a separate external sensing link. Figure 4 As shown, the use of a single external sensing link (e.g., external sensing link 430) having three portions coupled together and anchored to a substrate can convey various advantages, such as higher stiffness than previous approaches. As a result, translation and bending of the rigid portion of such a link can be lower than previous approaches, resulting in lower induced stresses and better reliability when a device (e.g., device 200) incorporating an external sensing link according to embodiments of the present invention experiences a large impact.

[0046] Figure 5 5 is a graph comparing the maximum deformation values ​​of two external sensing link structures in response to linear acceleration in the direction indicated by arrow 599. External sensing link 530 is an external sensing link (e.g., external sensing link 230 or 430) having a central portion 531 coupled to an external portion 535 via spring 534 according to embodiments herein. External sensing link 590 includes central portion 591 that is not similarly coupled to two external portions. As shown, in response to the same acceleration, the maximum displacement of external sensing link 530 is approximately two orders of magnitude lower than the maximum displacement at the corresponding position of external sensing link 590. Specific embodiments

[0048] Features of the embodiments may be understood with the aid of one or more of the following examples:

[0049] Example 1: An apparatus or method includes a first, second, third, and fourth mass blocks suspended above a substrate. The first mass block is adjacent to the second mass block and the third mass block. The second mass block is adjacent to the first mass block and the fourth mass block. The third mass block is adjacent to the first mass block and the fourth mass block. A first internal sensing link is disposed between the first mass block and the third mass block and is coupled to the first mass block and the third mass block. A second internal sensing link is disposed between the second mass block and the fourth mass block and is coupled to the second mass block and the fourth mass block. Each internal sensing link includes an upper portion, a lower portion, and a central torsional bend. The central torsional bend has a first end coupled to the upper portion of the internal sensing link and a second end coupled to the lower portion of the internal sensing link. A first torsion spring is coupled between the upper portion of the internal sensing link and the lower portion of the internal sensing link. An intermediate portion of the internal sensing link is coupled to the central torsional bend at a position between the first end of the central torsional bend and the second end of the central torsional bend. The first torsion spring is configured to exhibit an increase in stiffness when the upper and lower portions of the inner sense link move in phase with each other along an axis parallel to the central torsional bend and the upper and lower portions of the inner sense link are displaced a predetermined distance.

[0050] Example 2: A device or method according to any one of Example 1, wherein when the upper and lower portions of the internal sensing link move in phase with each other along an axis parallel to the central torsional bend and the upper and lower portions of the internal sensing link are displaced a predetermined distance, the first torsion spring is configured to impact one or both of the upper and lower portions of the internal sensing link.

[0051] Example 3: The device or method according to Example 1 or Example 2, wherein each internal sensing link also includes a second torsion spring. The second torsion spring is connected between the upper portion of the internal sensing link and the lower portion of the internal sensing link and is opposite to the first torsion spring. The second torsion spring has an intermediate portion that is connected to the central torsion bend at a position between the first end of the central torsion bend and the second end of the central torsion bend. When the upper portion and the lower portion of the internal sensing link move in phase with each other along an axis parallel to the central torsion bend and the upper portion and the lower portion of the internal sensing link are displaced a predetermined distance, the second torsion spring is configured to strike one or both of the upper portion of the internal sensing link and the lower portion of the internal sensing link.

[0052] Example 4: A device or method according to any one of Examples 1 to 3, wherein each internal sensing link further includes a first transverse bend and a second transverse bend. The first transverse bend is oriented perpendicular to the central torsion bend, and the first end of the central torsion bend is connected to a mass block corresponding to the upper portion of the internal sensing link. The second transverse torsion bend is oriented perpendicular to the central torsion bend, and the second end of the central torsion bend is connected to the mass block corresponding to the lower portion of the internal sensing link. Each transverse bend has a first and second arm including a corresponding folding spring. The middle portion of each folding spring of the first transverse bend is connected to the first end of the central torsion bend, and the outer portion of each folding spring of the first transverse bend is connected to the mass block corresponding to the upper portion of the internal sensing link. The middle portion of each folding spring of the second transverse bend is connected to the second end of the central torsion bend, and the outer portion of each folding spring of the second transverse bend is connected to the mass block corresponding to the lower portion of the internal sensing link.

[0053] Example 5: The device or method according to any one of Examples 1 to 4 further includes a first external sensing link, the first external sensing link is connected to the second outer edge of the first mass and the second mass; and a second external sensing link, the second external sensing link is opposite to the first external sensing link and is connected to the second outer edge of the third mass and the fourth mass. Each external sensing link includes: a central portion, the central portion is anchored to the substrate via an anchor, the anchor is surrounded by the central portion; a first external portion, the first external portion has a distal portion anchored to the substrate and a proximal end connected to the central portion via a first spring element; and a second external portion, the second external portion has a distal portion anchored to the substrate and a proximal end connected to the central portion via a second spring element.

[0054] Example 6: The apparatus or method of Example 5, wherein the first outer portion of the first external sense link is coupled to the first mass via a first spring element of the first external sense link, and the second outer portion of the first external sense link is coupled to the second mass via a second spring element of the first external sense link. The first external sense link is configured to exhibit a first stiffness value in response to out-of-phase motion of the first mass relative to the second mass. The first external sense link is configured to exhibit a second stiffness value greater than the first stiffness value in response to in-phase motion of the first mass relative to the second mass.

[0055] Example 7: The apparatus or method of Example 5 or Example 6, wherein the first outer portion of the second outer sense link is coupled to the third mass via a first spring element of the second outer sense link, and the second outer portion of the second outer sense link is coupled to the fourth mass via a second spring element of the second outer sense link. The second outer sense link is configured to exhibit a third stiffness value in response to out-of-phase motion of the third mass relative to the fourth mass. The second outer sense link is configured to exhibit a fourth stiffness value greater than the third stiffness value in response to in-phase motion of the third mass relative to the fourth mass.

[0056] Example 8: A device or method according to Example 7, wherein the second stiffness value is at least 4 times greater than the first stiffness value.

[0057] Example 9: A device or method according to any of Examples 7 or 8, wherein the fourth stiffness value is at least 4 times greater than the third stiffness value.

[0058] Example 10: An apparatus or method comprising a first, second, third, and fourth mass suspended above a substrate. The first mass is proximate to the second mass and the third mass. The second mass is proximate to the first mass and the fourth mass. The third mass is proximate to the first mass and the fourth mass. A first internal sense link is disposed between the first mass and the third mass and coupled to the first mass and the third mass. A second internal sense link is disposed between the second mass and the fourth mass and coupled to the second mass and the fourth mass. The example also includes: a first external sense link coupled to a second outer edge of the first mass and the second mass; and a second external sense link opposite the first external sense link and coupled to a second outer edge of the third mass and the fourth mass. Each external sensing link includes: a central portion, which is anchored to the substrate via an anchor, and the anchor is surrounded by the central portion; a first external portion, which has a distal portion anchored to the substrate and a proximal end connected to the central portion via a first spring element; and a second external portion, which has a distal portion anchored to the substrate and a proximal end connected to the central portion via a second spring element.

[0059] Example 11: An apparatus or method according to any of Examples 1 to 10, wherein each inner sensing link includes an upper portion; a lower portion; a central torsional bend having a first end coupled to the upper portion of the inner sensing link and a second end coupled to the lower portion of the inner sensing link; and a first torsion spring coupled between the upper portion of the inner sensing link and the lower portion of the inner sensing link; and each inner sensing link has an intermediate portion coupled to the central torsional bend at a position between the first end of the central torsional bend and the second end of the central torsional bend. The first torsion spring is configured to exhibit an increase in stiffness when the upper and lower portions of the inner sensing link move in phase with each other along an axis parallel to the central torsional bend and the upper and lower portions of the inner sensing link are displaced a predetermined distance.

[0060] Example 12: An apparatus or method according to any of Examples 1 to 11, wherein the first outer portion of each external sensing link is coupled to a first corresponding mass via a first spring element of the external sensing link, and the second outer portion of each external sensing link is coupled to a second corresponding mass via a second spring element of the external sensing link. Each external sensing link is configured to exhibit a first stiffness value in response to out-of-phase motion of the first corresponding mass relative to the second corresponding mass. Each first external sensing link is configured to exhibit a second stiffness value greater than the first stiffness value in response to in-phase motion of the first corresponding mass relative to the second corresponding mass.

[0061] The foregoing detailed description and examples are merely illustrative in nature and are not intended to limit the embodiments of the subject matter or the application and use of such embodiments. As used herein, the word "exemplary" means "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as being preferred or advantageous over other embodiments. In addition, no one is expected to be bound by any expressed or implied theory presented in the foregoing prior art, background, or detailed description.

[0062] It should be understood that the application of the present invention is not limited to the details of the construction and arrangement of the components set forth in the foregoing description or shown in the accompanying drawings. The present invention is capable of other embodiments and of being practiced or carried out in various ways. In addition, it should be understood that the words and terms used herein are for descriptive purposes and should not be considered restrictive. The use of "including / comprising" or "having" and its variations herein is intended to cover the items listed thereafter and their equivalents and additional items. Unless otherwise specified or limited, the terms "mount", "connect", "support" and "couple" and their variations are widely used and cover direct and indirect mounting, connection, support and connection. In addition, "connect" and "couple" are not limited to physical or mechanical connections or couplings.

[0063] The foregoing discussion is presented to enable those skilled in the art to implement and use embodiments of the present invention. Various modifications to the illustrated embodiments will become apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from embodiments of the present invention. Therefore, embodiments of the present invention are not intended to be limited to the illustrated embodiments, but should be given the widest scope consistent with the principles and features disclosed herein. The foregoing detailed description should be read with reference to the accompanying drawings, in which the same elements in different figures have the same reference numerals. The accompanying drawings, which may not be drawn to scale, depict selected embodiments and are not intended to limit the scope of embodiments of the present invention. Those skilled in the art will recognize that the examples provided herein have many useful alternatives and are within the scope of embodiments of the present invention.

[0064] The connecting lines shown in the various figures included herein are intended to represent exemplary functional relationships and / or physical connections between various elements. It should be noted that many alternative or additional functional relationships or physical connections may exist in one or more embodiments of the subject matter. In addition, specific terms may also be used herein only for reference purposes and therefore the specific terms are not intended to be restrictive, and unless the context clearly indicates, the terms "first", "second" and other such numerical terms referring to the reference structure do not imply a sequence or order.

[0065] The above description refers to elements or nodes or features being "connected" or "coupled" together. As used herein, unless otherwise expressly stated, "connected" means that one element is directly joined to another element (or directly communicates with another element), and not necessarily mechanically joined. Similarly, unless otherwise expressly stated, "coupled" means that one element is directly or indirectly joined to another element (or directly or indirectly communicates with another element electrically or otherwise), and not necessarily mechanically joined. Therefore, although the schematic diagrams shown in the figures depict an exemplary arrangement of elements, additional intervening elements, devices, features, or components may be present in one or more embodiments of the depicted subject matter.

Claims

1. A micro-electromechanical system (MEMS) device, characterized in that: include: substrate; first, second, third and fourth masses suspended above the substrate, wherein: The first mass block is adjacent to the second mass block and the third mass block; The second mass is adjacent to the first mass and the fourth mass; and The third mass block is adjacent to the first mass block and the fourth mass block; a first inner sense link disposed between and coupled to the first and third masses; and a second interior sensing link disposed between and coupled to the second mass and the fourth mass; Each internal sensing link includes: upper part; lower part; a central torsional bend having a first end coupled to the upper portion of the inner sense link and a second end coupled to the lower portion of the inner sense link; and a first torsion spring coupled between the upper portion of the inner sensing link and the lower portion of the inner sensing link; and the inner sensing link having a middle portion coupled to the central torsional bend at a location between the first end of the central torsional bend and the second end of the central torsional bend; and Wherein the first torsion spring is configured to exhibit an increase in stiffness when the upper and lower portions of the inner sensing link move in phase with each other along an axis parallel to the central torsional bend and the upper and lower portions of the inner sensing link are displaced a predetermined distance.

2. The MEMS device according to claim 1, characterized in that When the upper portion and the lower portion of the internal sensing link move in phase with each other along the axis parallel to the central torsional bend and the upper portion and the lower portion of the internal sensing link are displaced a predetermined distance, the first torsion spring is configured to impact one or both of the upper portion of the internal sensing link and the lower portion of the internal sensing link.

3. The MEMS device according to claim 1, wherein: Each internal sensing link also includes: a second torsion spring coupled between the upper portion of the inner sensing link and the lower portion of the inner sensing link and opposite the first torsion spring; and the inner sensing link having a middle portion coupled to the central torsion bend at a location between the first end of the central torsion bend and the second end of the central torsion bend; Wherein, when the upper portion and the lower portion of the internal sensing link move in phase with each other along an axis parallel to the central torsional bend and the upper portion and the lower portion of the internal sensing link are displaced a predetermined distance, the second torsion spring is configured to impact one or both of the upper portion of the internal sensing link and the lower portion of the internal sensing link.

4. The MEMS device according to claim 3, characterized in that Each internal sensing link also includes: a first lateral bend oriented perpendicular to the central torsional bend, the first lateral bend coupling the first end of the central torsional bend to a proof mass corresponding to the upper portion of the inner sense link; and a second lateral torsional bend oriented perpendicular to the central torsional bend, the second lateral torsional bend coupling the second end of the central torsional bend to a mass corresponding to the lower portion of the inner sense link; wherein each transverse bend has first and second arms including respective folding springs; wherein a middle portion of each folded spring of the first transverse bend is coupled to the first end of the central torsion bend and an outer portion of each folded spring of the first transverse bend is coupled to the mass corresponding to the upper portion of the inner sensing link; and Wherein a middle portion of each folding spring of the second transverse bend is connected to the second end of the central torsion bend, and an outer portion of each folding spring of the second transverse bend is connected to the mass block corresponding to the lower portion of the inner sensing link.

5. The MEMS device according to claim 1, wherein: Also includes: a first outer sensing link coupled to second outer edges of the first and second masses; as well as a second outer sensing link opposite the first outer sensing link and coupled to second outer edges of the third and fourth masses; Each external sensing link includes: a central portion anchored to the substrate via an anchor, the anchor being surrounded by the central portion; a first outer portion having a distal portion anchored to the base plate and a proximal end coupled to the central portion via a first spring element; and A second outer portion has a distal portion anchored to the base plate and a proximal end coupled to the central portion via a second spring element.

6. The MEMS device according to claim 5, It is characterized in that the first outer portion of the first outer sense link is coupled to the first mass via the first spring element of the first outer sense link, and the second outer portion of the first outer sense link is coupled to the second mass via the second spring element of the first outer sense link; wherein the first external sensing link is configured to exhibit a first stiffness value in response to out-of-phase motion of the first mass relative to the second mass; as well as Wherein the first outer sense link is configured to exhibit a second stiffness value greater than the first stiffness value in response to in-phase movement of the first proof-mass relative to the second proof-mass.

7. The MEMS device according to claim 6, It is characterized in that the first outer portion of the second outer sense link is coupled to the third mass via the first spring element of the second outer sense link, and the second outer portion of the second outer sense link is coupled to the fourth mass via the second spring element of the second outer sense link; wherein the second external sensing link is configured to exhibit a third stiffness value in response to out-of-phase motion of the third mass relative to the fourth mass; and Wherein the second outer sensing link is configured to exhibit a fourth stiffness value greater than the third stiffness value in response to in-phase movement of the third proof-mass relative to the fourth proof-mass.

8. The MEMS device according to claim 7, It is characterized in that The second stiffness value is at least 4 times greater than the first stiffness value.

9. The MEMS device according to claim 8, It is characterized in that The fourth stiffness value is at least 4 times greater than the third stiffness value.

10. A method, characterized in that The method comprises: forming first, second, third and fourth masses suspended above the substrate, wherein: The first mass block is adjacent to the second mass block and the third mass block; The second mass is adjacent to the first mass and the fourth mass; and The third mass block is adjacent to the first mass block and the fourth mass block; forming a first inner sense link disposed between and coupled to the first mass and the third mass; and forming a second inner sense link disposed between and coupled to the second mass and the fourth mass; Each internal sensing link includes: upper part; lower part; a central torsional bend having a first end coupled to the upper portion of the inner sense link and a second end coupled to the lower portion of the inner sense link; and a first torsion spring coupled between the upper portion of the inner sensing link and the lower portion of the inner sensing link; and the inner sensing link having a middle portion coupled to the central torsional bend at a location between the first end of the central torsional bend and the second end of the central torsional bend; and Wherein the first torsion spring is configured to exhibit an increase in stiffness when the upper and lower portions of the inner sensing link move in phase with each other along an axis parallel to the central torsional bend and the upper and lower portions of the inner sensing link are displaced a predetermined distance.

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