Fully symmetric structure for microelectromechanical device

Abstract

To provide a fully symmetric structure for a microelectromechanical device.SOLUTION: A fully symmetric sensing structure for a microelectromechanical system (MEMS) device is disclosed herein. In a certain embodiment, a MEMS sensor includes a proof mass that moves in a first direction. The proof mass includes movable fingers that move with the proof mass. The MEMS sensor further includes fixed fingers that are fixed relative to the movable fingers, and the fixed fingers and the movable fingers function to detect movement of the proof mass. For example, the movable fingers and the fixed fingers can be interdigitated to form a comb finger set for sensing change in capacitance resulting from movement of the proof mass relative to a substrate. A layout of the fixed finger is fully symmetrical at least in the first direction.SELECTED DRAWING: Figure 2B

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Embodiments of the present invention relate to electronic devices, and more particularly to micro-electro-mechanical systems (MEMS). [Background technology]

[0002] A MEMS sensor, such as a MEMS accelerometer or a MEMS gyroscope, includes a proof mass that moves in response to inertial forces. Additionally, the MEMS sensor includes a sensing structure, such as a capacitive sensing structure, having movable fingers attached to the proof mass and fixed fingers anchored to a substrate. The movable and fixed fingers can be interdigitated to form a comb finger set that functions to sense changes in capacitance resulting from the proof mass moving relative to the substrate.

[0003] In an accelerometer, a proof mass can be suspended by a spring tether above a substrate to provide resistance to acceleration forces. Additionally, a sensing structure measures the deflection of the proof mass, resulting in a sensor output having an amplitude proportional to acceleration. In another example, a gyroscope can include a proof mass that moves in a first direction (e.g., X direction) while a sensing structure detects a Coriolis effect in a second direction (e.g., Y direction) resulting from the movement of the proof mass. Summary of the Invention

[0004] In one aspect, a MEMS sensor is disclosed. The MEMS sensor includes a proof mass configured to move in a first direction, the proof mass including a plurality of movable fingers that move with the proof mass. The MEMS sensor further includes a plurality of fixed fingers fixed relative to the plurality of movable fingers. A layout of the plurality of fixed fingers is perfectly symmetrical in at least the first direction.

[0005] In another aspect, a method of MEMS sensing is disclosed. The method includes moving a proof mass in a first direction, the proof mass including a plurality of movable fingers that move with the proof mass. The method further includes sensing the movement of the proof mass using the plurality of movable fingers and a plurality of fixed fingers fixed relative to the plurality of movable fingers. A layout of the plurality of fixed fingers is perfectly symmetrical in at least the first direction. [Brief explanation of the drawings]

[0006] [Figure 1A] FIG. 1 is a plan view of an example MEMS accelerometer. [Figure 1B] FIG. 1B is a plan view of the capacitive sensing structure of the MEMS accelerometer of FIG. 1A. [Figure 2A] FIG. 1 is a plan view of a MEMS accelerometer having a fully symmetrical sensing structure, according to one embodiment. [Figure 2B] FIG. 2B is a plan view of the capacitive sensing structure of the MEMS accelerometer of FIG. 2A. [Figure 3A] FIG. 10 is a plan view of a capacitive sensing structure according to another embodiment. [Figure 3B] FIG. 3B is a first cross-sectional view of the capacitive sensing structure of FIG. 3A. [Figure 3C] FIG. 3B is a second cross-sectional view of the capacitive sensing structure of FIG. 3A. [Figure 4A] FIG. 10 is a plan view of a capacitive sensing structure according to another embodiment. [Figure 4B] FIG. 4B is a first cross-sectional view of the capacitive sensing structure of FIG. 4A. [Figure 4C] FIG. 4B is a second cross-sectional view of the capacitive sensing structure of FIG. 4A. [Figure 5A] FIG. 10 is a plan view of a capacitive sensing structure according to another embodiment. [Figure 5B] FIG. 5B is a first cross-sectional view of the capacitive sensing structure of FIG. 5A. [Figure 5C] FIG. 5B is a second cross-sectional view of the capacitive sensing structure of FIG. 5A. [Figure 5D] FIG. 5B is a third cross-sectional view of the capacitive sensing structure of FIG. 5A. [Figure 6]FIG. 10 is a plan view of a capacitive sensing structure according to another embodiment. [Figure 7A] FIG. 10 is a plan view of a capacitive sensing structure according to another embodiment. [Figure 7B] FIG. 7B is a first cross-sectional view of the capacitive sensing structure of FIG. 7A. [Figure 7C] FIG. 7B is a second cross-sectional view of the capacitive sensing structure of FIG. 7A. [Figure 7D] FIG. 7B is a third cross-sectional view of the capacitive sensing structure of FIG. 7A. [Figure 8A] FIG. 1 is a plan view of an example of a MEMS gyroscope. [Figure 8B] FIG. 8B is a plan view of the capacitive sensing structure of the MEMS gyroscope of FIG. 8A. [Figure 9A] FIG. 1 is a plan view of a MEMS gyroscope having a fully symmetrical sensing structure, according to one embodiment. [Figure 9B] FIG. 9B is a plan view of the capacitive sensing structure of the MEMS gyroscope of FIG. 9A. DETAILED DESCRIPTION OF THE INVENTION

[0007] The following detailed description of the embodiments presents various descriptions of specific embodiments of the present invention. However, the present invention can be embodied in many different ways. In this description, reference is made to the drawings, where like reference numbers may indicate identical or functionally similar elements. It will be understood that the elements illustrated in the drawings are not necessarily drawn to scale. Furthermore, it will be understood that a particular embodiment may include more elements than illustrated in the drawings and / or a subset of the elements illustrated in the drawings. Furthermore, some embodiments may incorporate any suitable combination of features from two or more drawings.

[0008] Certain MEMS sensors are designed with movable fingers that may have some degree of symmetry. However, such designs are not perfectly symmetrical due to layout constraints. For example, a MEMS sensor may have fixed fingers that extend to only one side of a fixed anchor; when the anchor rotates due to stress, the sensing gap changes and results in a change in sensor offset and / or quadrature error.

[0009] A fully symmetrical sensing structure for a MEMS device is disclosed herein. In one specific embodiment, the MEMS sensor includes a proof mass that moves in a first direction. The proof mass includes movable fingers that move with the proof mass. The MEMS sensor further includes fixed fingers that are fixed relative to the movable fingers, and the fixed fingers and movable fingers function to detect movement of the proof mass. For example, the movable fingers and fixed fingers can be interdigitated to form a comb finger set for sensing changes in capacitance resulting from movement of the proof mass relative to the substrate. The layout of the fixed fingers is fully symmetrical in at least the first direction.

[0010] Implementing a MEMS sensor with a perfectly symmetrical sensing structure achieves significant offset performance under packaging and / or internal / external stress. For example, an asymmetric design of the comb finger set causes offset shift due to different movements of the fixed fingers under stress.

[0011] Thus, provided herein is a perfectly symmetrical sensing structure for a MEMS sensor, such as a MEMS accelerometer or a MEMS gyroscope. The structure is perfectly symmetrical in at least one direction by design (perfectly symmetrical without manufacturing variations or defects). In certain embodiments, the structure is perfectly symmetrical in at least two directions. A MEMS sensor is also referred to herein as a MEMS device.

[0012] Thus, each fixed finger can be perfectly symmetrical with respect to its anchor and / or each set of fixed fingers can be perfectly symmetrical with respect to the movable finger, thus canceling the effects of fixed finger anchor rotation.

[0013] The MEMS sensor can also be implemented with co-aligned fixed finger anchors, which reduces the offset created by differences in the positions of the fixed anchors.

[0014] Such co-alignment of the anchors of the fixed fingers can be implemented in a variety of ways, for example, the fixed fingers can be anchored to the substrate only at the center of each finger fully anchored by the entire finger, at the ends of each finger, and / or in any other desired configuration of anchoring by co-alignment.

[0015] In certain embodiments, the anchors for the fixed fingers are conductive and function to provide an electrical connection to the polysilicon or metal conductor. The conductive anchors thus allow for the potential of the conductor to be controlled and / or sensed. The anchors can also include one or more anchors formed from oxide, such as by an additional oxide / dielectric layer underneath the finger. Such oxide finger anchors are non-conductive but provide a structural anchoring function for the fixed finger.

[0016] In one example, the oxide finger anchors are formed from a sacrificial oxide that is also used directly beneath the proof mass. The sacrificial oxide is removed directly beneath the proof mass to form a cavity and left directly beneath the fingers to form the oxide finger anchors. In another example, the oxide is pre-etched and the fingers are bonded onto the pre-etched oxide. Any suitable oxide or other dielectric layer can be used to form the non-conductive finger anchors.

[0017] Figure 1A is a plan view of an example of a MEMS accelerometer 30. The MEMS accelerometer 30 includes a substrate 11, a proof mass 12, a spring 13, a spring anchor 14, a stopper 15, a first directional capacitive sensing structure 17, and a second directional capacitive sensing structure 18. Figure 1B is a plan view of one of the first directional capacitive sensing structures 17 of the MEMS accelerometer 30 of Figure 1A.

[0018] 1A-1B, MEMS accelerometer 30 includes a proof mass 12 suspended by springs 13 above a substrate 11. MEMS accelerometer 30 also includes capacitive sensing structures 17 / 18 for measuring deflection of proof mass 12 in first and second directions.

[0019] 1B, capacitive sensing structure 17 includes movable fingers 21 that move with proof mass 12. Capacitive sensing structure 17 also includes a first set of fixed fingers 23 anchored to substrate 11 by a first set of finger anchors 25 and a second set of fixed fingers 24 anchored to substrate 11 by a second set of finger anchors 26. Movable fingers 21 and fixed fingers 23 / 24 interdigitate to form a comb finger set for sensing capacitance. The comb finger set detects deflection of proof mass 12 as the sensed capacitance changes.

[0020] With continued reference to FIGS. 1A and 1B, the layout of each capacitive sensing structure has some asymmetry.

[0021] 1B, the movable fingers 21 of the capacitive sensing structure 17 extend from only one side of the proof mass 12. Furthermore, the first set of finger anchors 25 and the second set of finger anchors 26 are positioned at one end of each finger. Furthermore, the first set of finger anchors 25 are not aligned with the second set of finger anchors 26.

[0022] Such asymmetry results in a change in the sensor offset. For example, when the finger anchor rotates due to stress, the sensing gap between the movable finger 21 and the fixed fingers 23 / 24 changes, causing a change in the sensor offset.

[0023] Figure 2A is a plan view of a MEMS accelerometer 50 having a fully symmetrical sensing structure, according to one embodiment. MEMS accelerometer 50 includes substrate 11, proof mass 12, spring 13, spring anchor 14, stopper 15, first directional capacitive sensing structure 37, and second directional capacitive sensing structure 38. Figure 2B is a plan view of one of first directional capacitive sensing structures 37 of MEMS accelerometer 50 of Figure 2A.

[0024] 2A-2B, MEMS accelerometer 50 includes a proof mass 12 suspended by springs 13 above a substrate 11. MEMS accelerometer 50 also includes a capacitive sensing structure 37 / 38 for measuring deflection of proof mass 12.

[0025] 2B, the capacitive sensing structure 37 includes movable fingers 41 that move with the proof mass 12. The capacitive sensing structure 37 also includes a first set of fixed fingers 43 that are anchored to the substrate 11 by a first set of finger anchors 45 and a second set of fixed fingers 44 that are anchored to the substrate 11 by a second set of finger anchors 46. The movable fingers 41 and the fixed fingers 43 / 44 interdigitate to form a comb finger set for sensing capacitance.

[0026] With continued reference to Figures 2A and 2B, the layout of each capacitive sensing structure is perfectly symmetrical.

[0027] For example, as shown in FIG. 2B, the movable fingers 41 of the capacitive sensing structure 37 extend symmetrically from both sides of the proof mass 12, rather than just from one side.

[0028] Additionally, the fixed fingers 43 / 44 shown in Figure 2B are symmetrically anchored, in contrast to the fixed fingers 23 / 24 shown in Figure 1B, which are anchored only at one end of each finger.

[0029] Additionally, the first set of finger anchors 45 are aligned with the second set of finger anchors 46 along the y-axis 47. Such anchor co-alignment reduces sensor offsets created by differences in fixed anchor position / stress.

[0030] The movable finger 41 is therefore perfectly symmetrical with respect to the y-axis 47 as well as the x-axis 48 in this embodiment.

[0031] In the illustrated embodiment, the capacitive sensing structure 37 is mirror symmetric with respect to both the y-axis 47 and the x-axis 48. Such symmetry achieves significant improvements in offset performance under packaging and / or internal / external stress compared to asymmetric designs.

[0032] Figure 3A is a plan view of a capacitive sensing structure 150 according to another embodiment. Figure 3B is a first cross-sectional view of the capacitive sensing structure 150 of Figure 3A taken along line 3B. Figure 3C is a second cross-sectional view of the capacitive sensing structure 150 of Figure 3A taken along line 3C.

[0033] Capacitive sensing structure 150 is formed above substrate 140 and includes movable finger 141, first fixed finger 143, second fixed finger 144, first fixed finger central anchor 145, and second fixed finger central anchor 146. Capacitive sensing structure 150 is an example of a perfectly symmetrical capacitive sensing structure that may be included in a MEMS sensor.

[0034] Movable finger 141 is attached to a proof mass, not shown in Figures 3A and 3B. The proof mass and movable finger 141 move relative to substrate 140 and fixed fingers 143 / 144, which are anchored to substrate 140.

[0035] The layout of the capacitive sensing structure 150 is perfectly symmetric in both the x and y directions.

[0036] In the illustrated embodiment, the first fixed finger 143 is anchored to the substrate 140 by a first fixed finger central anchor 145 that is located at the center of the first fixed finger 143. Additionally, the second fixed finger 144 is anchored to the substrate 140 by a second fixed finger central anchor 146 that is located at the center of the second fixed finger 144. The first fixed finger central anchor 145 and the second fixed finger central anchor 146 are aligned to provide co-alignment that reduces sensor offset.

[0037] Although Figures 3A-3C depict an embodiment in which the fixed fingers are centrally anchored, the teachings herein are applicable to fixed fingers that are otherwise anchored.

[0038] In the illustrated embodiment, the first fixed finger center anchor 145 and the second fixed finger center anchor 146 are conductive anchors that are both used not only to anchor the fixed fingers but also to provide corresponding electrical connections to metal or polysilicon conductors formed on the substrate 140.

[0039] Figure 4A is a plan view of a capacitive sensing structure 160 according to another embodiment. Figure 4B is a first cross-section of the capacitive sensing structure 160 of Figure 4A taken along line 4B. Figure 4C is a second cross-section of the capacitive sensing structure 160 of Figure 4A taken along line 4C.

[0040] Capacitive sensing structure 160 is formed above substrate 140 and includes movable finger 141, first fixed finger 143, second fixed finger 144, first fixed finger full anchor 155, and second fixed finger full anchor 156. Capacitive sensing structure 160 is another example of a fully symmetrical capacitive sensing structure that may be included in a MEMS sensor.

[0041] Capacitive sensing structure 160 of Figures 4A-4C is similar to capacitive sensing structure 150 of Figures 3A-3C, except that first fixed finger full anchor 155 and second fixed finger full anchor 156 are whole finger anchors. Thus, whole finger anchors are used in Figures 4A-4C, rather than just anchoring a fixed finger in the center as in Figures 3A-3C.

[0042] As shown in Figure 4B, a portion of the entire finger anchor includes oxide anchors 157 / 158 that are electrically non-conductive. Additionally, as shown in Figure 4C, electrical anchors 155 / 156 are also used to provide corresponding electrical connections to metal or polysilicon conductors formed on substrate 140.

[0043] 4A-4C uses a combination of oxide anchors and conductive anchors. The oxide anchors provide a mechanical connection and can be connected to any desired structure. The conductive anchors provide an electrical connection as well as a mechanical connection.

[0044] The oxide anchors herein can be formed using any suitable oxide or other dielectric layer. In one example, the oxide anchors are formed from a sacrificial oxide that is also used directly beneath the proof mass. Such sacrificial oxide is removed directly beneath the proof mass to form a cavity and left behind directly beneath the fingers to form the oxide finger anchors. In another example, the oxide is pre-etched and the fingers are bonded onto the pre-etched oxide.

[0045] Figure 5A is a plan view of a capacitive sensing structure 170 according to another embodiment. Figure 5B is a first cross-section of the capacitive sensing structure 170 of Figure 5A taken along line 5B. Figure 5C is a second cross-section of the capacitive sensing structure 170 of Figure 5A taken along line 5C. Figure 5D is a third cross-section of the capacitive sensing structure 170 of Figure 5A taken along line 5D.

[0046] Capacitive sensing structure 170 is formed above substrate 140 and includes movable finger 141, first fixed finger 143, second fixed finger 144, first fixed finger center anchor 165, first fixed finger end anchor 167, second fixed finger center anchor 166, and second fixed finger end anchor 168. Capacitive sensing structure 170 is another example of a fully symmetrical capacitive sensing structure that may be included in a MEMS sensor.

[0047] The capacitive sensing structure 170 of Figures 5A-5D is similar to the capacitive sensing structure 150 of Figures 3A-3C, except that the capacitive sensing structure 170 of Figures 5A-5D anchors the fixed fingers to the substrate 140 at both the center and end points of the fixed fingers.

[0048] As shown in Figure 5B, first fixed finger end anchor 167 and second fixed finger end anchor 168 are oxide anchors. Additionally, as shown in Figure 5D, first fixed finger center anchor 165 and second fixed finger center anchor 166 are conductive anchors that also provide electrical connection to corresponding conductors on substrate 140.

[0049] FIG. 6 is a plan view of a capacitive sensing structure 180 according to another embodiment.

[0050] Capacitive sensing structure 180 is formed above substrate 140 and includes movable finger 141, first fixed finger 143, second fixed finger 144, first fixed finger center anchor 165, first fixed finger end anchor 167, first fixed finger midpoint anchor 175, second fixed finger center anchor 166, second fixed finger end anchor 168, and second fixed finger midpoint anchor 176. Capacitive sensing structure 180 is another example of a fully symmetrical capacitive sensing structure that may be included in a MEMS sensor.

[0051] The capacitive sensing structure 180 of FIG. 6 is similar to the capacitive sensing structure 170 of FIGS. 5A-5D, except that the capacitive sensing structure 180 of FIG. 6 further anchors fixed fingers to the substrate 140 at the midpoint.

[0052] Figure 7A is a plan view of a capacitive sensing structure 190 according to another embodiment. Figure 7B is a first cross-section of the capacitive sensing structure 190 of Figure 7A taken along line 7B. Figure 7C is a second cross-section of the capacitive sensing structure 190 of Figure 7A taken along line 7C. Figure 7D is a third cross-section of the capacitive sensing structure 190 of Figure 7A taken along line 7D.

[0053] Capacitive sensing structure 190 is formed above substrate 140 and includes movable finger 141, first fixed finger 143, second fixed finger 144, first fixed finger half anchor 185, and second fixed finger half anchor 186. Capacitive sensing structure 190 is another example of a fully symmetrical capacitive sensing structure that may be included in a MEMS sensor.

[0054] Capacitive sensing structure 190 of Figures 7A-7D is similar to capacitive sensing structure 150 of Figures 3A-3C, except that fixed finger half anchor 185 and second fixed finger half anchor 186 are half finger anchors. Thus, rather than simply anchoring the fixed finger in the center as in Figures 3A and 3B, half finger anchors are used in Figures 7A-7D.

[0055] As shown in Figure 7C, some of the half finger anchors include oxide anchors 187 / 188 that are electrically non-conductive. Additionally, as shown in Figure 7D, electrical anchors 185 / 186 are also used to provide corresponding electrical connections to metal or polysilicon conductors formed on substrate 140.

[0056] Figure 8A is a plan view of an example of a MEMS gyroscope 330. The gyroscope 330 includes a substrate 311, a proof mass 312 (also referred to as a resonator mass), a spring 313, an anchor 314, a drive structure 316, and a capacitive sensing structure 317. Figure 8B is a plan view of one of the capacitive sensing structures 317 of the MEMS gyroscope 330 of Figure 8A.

[0057] 8A-8B, MEMS gyroscope 330 includes a proof mass 312 suspended by springs 313 above a substrate 311. Proof mass 312 is driven in a first direction by a drive structure 316, and a capacitive sensing structure 317 measures deflection of proof mass 312 in a second direction resulting from the Coriolis effect.

[0058] 8B, capacitive sensing structure 317 includes movable fingers 321 that move with proof mass 312. Capacitive sensing structure 317 also includes a first set of fixed fingers 323 that are anchored to substrate 311 by a first set of finger anchors 325 and a second set of fixed fingers 324 that are anchored to substrate 311 by a second set of finger anchors 326. Movable fingers 321 and fixed fingers 323 / 324 interdigitate to form a comb finger set for sensing capacitance.

[0059] With continued reference to Figures 8A and 8B, the layout of each of the capacitive sensing structures 317 has some asymmetries.

[0060] For example, as shown in Figure 8B, fixed finger 323 and second fixed finger 324 are not perfectly symmetrical with respect to each other with respect to movable finger 321, but are anchored at only one end. Furthermore, first set of finger anchors 325 are not aligned with second set of finger anchors 326.

[0061] Such asymmetry causes changes in offset and / or quadrature error. For example, when the finger anchor rotates due to stress, the sensing gap between the movable finger 321 and the fixed fingers 323 / 324 changes, leading to undesirable sensor offset or quadrature error terms.

[0062] Figure 9A is a plan view of a MEMS gyroscope 350 having a fully symmetrical sensing structure, according to one embodiment. The MEMS gyroscope 350 includes a substrate 311, a proof mass 312, a spring 313, an anchor 314, a drive structure 316, and a capacitive sensing structure 337. Figure 9B is a plan view of one of the capacitive sensing structures 337 of the MEMS gyroscope 350 of Figure 9A.

[0063] 9B, capacitive sensing structure 337 includes movable fingers 341 that move with proof mass 312. Capacitive sensing structure 337 also includes a first set of fixed fingers 343 that are anchored to substrate 311 by a first set of finger anchors 345 and a second set of fixed fingers 344 that are anchored to substrate 311 by a second set of finger anchors 346. Movable fingers 341 and fixed fingers 343 / 344 interdigitate to form a comb finger set for sensing capacitance.

[0064] With continued reference to Figures 9A and 9B, the layout of each capacitive sensing structure is perfectly symmetrical.

[0065] For example, as shown in FIG. 9B, the movable fingers 341 of the capacitive sensing structure 337 extend symmetrically from both sides of the proof mass 312 and are perfectly symmetrical with respect to the first set of fixed fingers 343 and the second set of fixed fingers 344.

[0066] Additionally, the fixed fingers 343 / 344 shown in Figure 9B are symmetrically anchored, in contrast to the fixed fingers 323 / 324 shown in Figure 8B, which are anchored at only one end of each finger.

[0067] Additionally, the first set of finger anchors 345 are aligned with the second set of finger anchors 346. Such anchor co-alignment reduces sensor offset and / or quadrature error produced by differences in the positions of the fixed anchors.

[0068] [Conclusion] The foregoing description may refer to elements or features as being "connected" or "coupled" together. As used herein, unless expressly stated otherwise, "connected" means that one element / feature is directly or indirectly connected to another element / feature, but not necessarily mechanically connected. Similarly, unless expressly stated otherwise, "coupled" means that one element / feature is directly or indirectly coupled to another element / feature, but not necessarily mechanically coupled. Thus, while the various schematics shown in the figures depict example configurations of elements and components, additional intervening elements, devices, features, or components may be present in an actual embodiment (provided that the functionality of the depicted circuit is not adversely affected).

[0069] While certain embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the present disclosure. Indeed, the novel apparatus, methods, and systems described herein may be embodied in a variety of other forms, and various omissions, substitutions, and changes may be made in the form of the methods and systems described herein without departing from the spirit of the present disclosure. For example, while the disclosed embodiments are presented in a given configuration, alternative embodiments may perform similar functionality with different components and / or circuit topologies, and may delete, move, add, subdivide, combine, and / or modify certain elements. Each of these elements may be implemented in a variety of different ways. Any suitable combination of elements and acts of the various embodiments described above may be combined to provide further embodiments. Accordingly, the scope of the present invention is defined solely by reference to the appended claims.

[0070] The claims presented herein are in single dependent form for filing with the USPTO, but it should be understood that any claim may depend on any preceding claim of the same type unless clearly technically impractical. [Explanation of symbols]

[0071] 12 Proof Mass 37, 150, 160, 170, 180, 190, 337 capacitive sensing structure 41, 141, 341 Movable finger 43, 143, 343 First set of fixed fingers 44, 144, 344 Second set of fixed fingers 47 y-axis 48 x-axis

Claims

1. 1. A micro-electromechanical system (MEMS) sensor comprising: a proof mass configured to move in a first direction, the proof mass including a plurality of movable fingers that move with the proof mass; a plurality of fixed fingers fixed relative to the plurality of movable fingers; Equipped with A MEMS sensor, wherein the layout of the plurality of fixed fingers is perfectly symmetrical in at least the first direction.

2. The MEMS sensor of claim 1 , wherein each of the plurality of fixed fingers is anchored using at least one conductive anchor.

3. The MEMS sensor of claim 1 , wherein each of the plurality of fixed fingers is anchored using at least one dielectric anchor.

4. The MEMS sensor of claim 1 , wherein each of the plurality of fixed fingers is anchored using at least one dielectric anchor and at least one conductive anchor.

5. The MEMS sensor of claim 1 further comprising a substrate, the plurality of fixed fingers being symmetrically fixed to the substrate.

6. The MEMS sensor of claim 5 , wherein each of the plurality of fixed fingers includes a center anchored to the substrate.

7. The MEMS sensor of claim 5 , wherein a first end and a second end of each of the plurality of fixed fingers are anchored to the substrate.

8. The MEMS sensor of claim 5 , wherein each of the plurality of fixed fingers is anchored to the substrate at three or more points.

9. The MEMS sensor of claim 1 , wherein the layout of the plurality of fixed fingers is completely symmetrical in the first direction and the second direction.

10. The MEMS sensor of claim 9 , wherein the layout of the plurality of movable fingers is also completely symmetrical in the first direction and the second direction.

11. The MEMS sensor of claim 9 , wherein the plurality of fixed fingers and the plurality of movable fingers form a capacitive sensing structure.

12. The MEMS sensor of claim 11 , wherein the capacitive sensing structure detects a Coriolis effect in the second direction resulting from movement of the proof mass in the first direction.

13. The MEMS sensor of claim 11 , wherein the capacitive sensing structure detects deflection of the proof mass to generate a sensor output having an amplitude proportional to acceleration.

14. The MEMS sensor of claim 1 implemented as a gyroscope.

15. The MEMS sensor of claim 1 implemented as an accelerometer.

16. 1. A method of micro-electromechanical systems (MEMS) sensing, said method comprising: moving a proof mass in a first direction, the proof mass including a plurality of movable fingers that move with the proof mass; sensing movement of the proof mass using the plurality of movable fingers and a plurality of fixed fingers fixed relative to the plurality of movable fingers; Including, A method wherein the layout of the plurality of fixed fingers is perfectly symmetrical in at least the first direction.

17. The method of claim 16 further comprising a substrate, the plurality of fixed fingers being symmetrically secured to the substrate.

18. The method of claim 16 , wherein the layout of the plurality of fixed fingers is completely symmetrical in the first and second directions.

19. 20. The method of claim 18, wherein the layout of the plurality of movable fingers is also completely symmetrical in the first direction and the second direction.

20. The method of claim 16 , wherein each of the plurality of fixation fingers is anchored using at least one dielectric anchor and at least one conductive anchor.

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