MEMS structures for minimizing out-of-plane sensing accelerometer offsets

Abstract

Exemplary embodiments of tilted z-axis out-of-plane sensing MEMS accelerometers and related structures and configurations are described. The disclosed embodiments facilitate improved offset stability. Non-limiting embodiments provide exemplary MEMS structures and devices featuring one or more sensing MEMS structures having symmetry about an axis orthogonal to a spring or elastic coupling axis, a spring or elastic coupling axis aligned with one of the symmetry axes of an electrode pattern, different numbers of reference electrodes and sensing electrodes, a reference MEMS structure having at least two symmetry axes (one of which is along the axis of the spring or elastic coupling), and / or a reference structure below the spring or elastic coupling axis.

Description

[0001] Priority claim

[0002] No. 16 / 673,602, filed on November 4, 2019, and entitled “OFFSET REJECTION ELEMENTS,” which is a continuation-in-part of and claims priority to U.S. patent application Ser. No. 16 / 673,602, filed on March 8, 2018, and entitled “OFFSET REJECTION ELEMENTS,” filed on November 4, 2019. This application claims priority to U.S. non-provisional application Ser. No. 16 / 842,619, filed on April 7, 2020, and entitled “MEMS STRUCTURE FOR OFFSET MINIMIZATION OF OUT-OF-PLANESENSING ACCELEROMETERS,” which is a continuation-in-part of and claims priority to U.S. patent application Ser. No. 16 / 673,602, filed on March 8, 2018, and entitled “OFFSET REJECTION ELEMENTS,” filed on March 4, 2019. No. 15 / 916,105, entitled “OFFSET REJECTION ELECTRODES,” filed on May 15, 2015 (now U.S. Patent No. 9,952,252), is a continuation of U.S. patent application serial number 15 / 916,105, entitled “OFFSET REJECTION ELECTRODES,” which is a divisional application of U.S. patent application serial number 14 / 714,149, entitled “OFFSET REJECTION ELECTRODES,” filed on May 15, 2015 (now U.S. Patent No. 9,952,252). In addition, this patent application claims priority to U.S. non-provisional application serial number 16 / 842,619, filed on April 7, 2020, entitled “MEMS STRUCTURE FOR OFFSET MINIMIZATION OF OUT-OF-PLANE SENSING ACCELEROMETERS,” and U.S. provisional patent application serial number 62 / 898,887, filed on September 11, 2019, entitled “MEMS STRUCTURE FOR OFFSET MINIMIZATION OF OUT-OF-PLANE SENSING ACCELEROMETERS.” This application is also related to U.S. Patent Application Serial No. 15 / 609,757 filed on May 31, 2017 (now U.S. Patent No. 10,295,558), which is a continuation-in-part of U.S. Patent Application Serial No. 14 / 714,149 filed on May 15, 2015 (now U.S. Patent No. 9,952,252), entitled “OFFSET REJECTION ELECTRODES”. The entire contents of the above applications are incorporated herein by reference. Technical Field

[0003] The disclosed subject matter relates to microelectromechanical system (MEMS) sensors, and more particularly, to MEMS sensors utilizing offset rejection electrodes. Background Art

[0004] Microelectromechanical systems (MEMS) sensors are subject to a variety of undesirable forces that may arise from the fabrication of the MEMS / complementary metal oxide semiconductor (CMOS) die, packaging of the die, operation at temperature, shock conditions, user assembly, and many other factors. These forces can cause non-ideal conditions such as deviations from parallel alignment between the MEMS sensor and the embedded sensing reference plane.

[0005] The offset minimization and substrate deformation suppression of MEMS accelerometers are usually addressed through MEMS sensor design considerations (e.g., anchor design, anchor placement, electrode placement and patterning, process improvements, etc.). However, the offset stability of MEMS accelerometers is a key challenge as specification limits are tightening across all market segments (e.g., consumer, automotive, industrial, etc.) and stress testing is becoming more aggressive. For example, improved offset stability is required for different types of external loads (e.g., temperature, strain, etc.) to enable new applications in existing markets or to adapt MEMS-based inertial sensors to new market segments.

[0006] It is therefore desirable to provide a MEMS sensor that improves these and other disadvantages. The disadvantages described above are intended only to provide an overview of some of the problems with conventional implementations and are not exhaustive. Other problems with conventional implementations and techniques, as well as the corresponding benefits of the various aspects described herein, will become more apparent after reading the following description. Summary of the invention

[0007] The following is a simplified summary of the specification to provide a basic understanding of the specification. This summary is not an extensive overview of the specification, and its purpose is not to identify the key or important content of the specification, nor is it intended to delineate the specific scope of any embodiment of the specification, or any scope of the claims. Its sole purpose is to present some concepts of the specification in a simplified form as a more detailed description will be presented later.

[0008] The present invention discloses a system and method for reducing offset in a micro-electromechanical system sensor. In a first aspect, the system is a micro-electromechanical system sensor, which includes a sensing reference plane, at least one anchor coupled to the sensing reference plane, at least one proof mass coupled to the at least one anchor, wherein one of the at least one proof mass moves under an external stimulus, a pattern of sensing elements coupled between the sensing reference plane and the at least one proof mass to detect motion perpendicular to the sensing reference plane, wherein the sensing elements of the pattern share at least three polarity antisymmetric axes, and a signal processing circuit to combine the sensing elements of the pattern to provide an output proportional to the external stimulus.

[0009] In a second aspect, the sensing reference plane is divided by two axes to form four quadrants on the sensing reference plane, and the sensing elements of the pattern include at least three sensing elements in each of the four quadrants.

[0010] In a third aspect, a method provides a MEMS sensor as described in the first and second aspects above.

[0011] In another non-limiting aspect, further non-limiting embodiments provide exemplary MEMS structures and devices featuring one or more sensing MEMS structures having symmetry about an axis orthogonal to the spring or elastic coupling axis, a spring or elastic coupling axis aligned with one of the symmetry axes of the electrode pattern, a different number of reference electrodes and sensing electrodes, a reference MEMS structure having at least two axes of symmetry (one of which is along the axis of the spring or elastic coupling), and / or a reference structure below the spring or elastic coupling axis.

[0012] These and other embodiments are described in greater detail below. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Various non-limiting embodiments are further described with reference to the accompanying drawings, in which:

[0014] Figure 1 illustrates a cross-sectional view of ideal and non-ideal MEMS sensor conditions according to an embodiment;

[0015] Figure 2A illustrates a cross-sectional view of a substrate portion of a MEMS sensor having a sensing element having a pattern according to an embodiment;

[0016] Figure 2B shows a top view of a substrate portion of a MEMS sensor having a pattern of sensing elements according to an embodiment;

[0017] Figure 2C A MEMS device of a MEMS sensor according to an embodiment is shown;

[0018] Figure 3A A top view of a MEMS sensor having a pattern of sensing elements and a corresponding MEMS structure according to another embodiment is shown;

[0019] Figure 3B A MEMS accelerometer structure of a MEMS sensor using an electrode pattern according to an embodiment is shown;

[0020] Figure 4 shows a top view of a MEMS sensor having a pattern of sensing elements according to another embodiment;

[0021] Figure 5 shows a top view of a MEMS sensor having a pattern of sensing elements according to another embodiment;

[0022] Figure 6 shows a top view of a MEMS sensor having a pattern of sensing elements according to another embodiment;

[0023] Figure 7 depicts various aspects of another non-limiting embodiment of a reference MEMS structure for an exemplary MEMS device as described herein;

[0024] Figure 8 Describes further non-limiting aspects of a sensing MEMS structure for another exemplary embodiment;

[0025] Fig. 9 depicts further non-limiting aspects for exemplary elastic couplings according to exemplary embodiments described herein;

[0026] Fig.10 depicts various aspects of non-limiting embodiments of sensing electrodes for exemplary devices as described herein;

[0027] Fig.11 Further aspects of non-limiting embodiments of reference electrodes for exemplary devices are shown;

[0028] Fig.12 further non-limiting aspects of exemplary devices as described herein are depicted;

[0029] Fig.13 Further non-limiting aspects of exemplary devices for electrode configurations are shown;

[0030] Fig.14 depicts various aspects of an exemplary reference MEMS structure according to further non-limiting embodiments described herein;

[0031] Fig.15depicts further non-limiting aspects of exemplary MEMS sensing structures according to other non-limiting embodiments; and

[0032] Fig.16 Depicted are exemplary embodiments of tilted Z-axis out-of-plane sensing MEMS accelerometers according to various aspects described herein. DETAILED DESCRIPTION

[0033] Although a brief overview is provided, certain aspects of the disclosure described or depicted herein are intended to be illustrative and not limiting. Therefore, variations of the disclosed embodiments suggested by the disclosed apparatus, systems, and methods are intended to be included within the scope of the subject matter disclosed herein. The following description is presented to enable one of ordinary skill in the art to make and use the various disclosed embodiments, and is provided in the context of patent applications and their requirements. Various modifications to the preferred embodiments and the general principles and features described herein will be readily apparent to one of ordinary skill in the art. Therefore, the disclosed subject matter is not intended to be limited to the embodiments shown, but is intended to conform to the widest scope consistent with the principles and features described herein.

[0034] Microelectromechanical systems (MEMS) refer to a class of microscale devices that are manufactured using semiconductor-like processes and exhibit mechanical properties such as the ability to move or deform. MEMS often (but not always) interact with electrical signals. A MEMS device may refer to a semiconductor device implemented as a MEMS. A MEMS device includes mechanical elements and, optionally, electronic elements for sensing. MEMS devices include, but are not limited to, microscale gyroscopes, accelerometers, magnetometers, and pressure sensors.

[0035] In one embodiment, a MEMS sensor includes a MEMS device, a sensing reference plane, and an anchor connecting the MEMS device to the sensing reference plane. During the manufacturing and operation of the MEMS sensor, the MEMS sensor may be subjected to undesirable forces. These undesirable forces include, but are not limited to, stresses from MEMS / CMOS chip manufacturing and packaging, operation at excessive temperatures, shock conditions, and user assembly, all of which can result in non-ideal conditions, such as deviations from parallel alignment between the MEMS device and the sensing reference plane.

[0036] There are at least two independent undesirable deviations from the parallel alignment between the MEMS device and the sensing reference plane. First, shear forces on the anchor cause the anchor to tilt relative to the sensing reference plane. Second, bending forces cause the sensing reference plane to bend relative to the MEMS device. Therefore, the gap z(x,y) between the sensing reference plane and the MEMS device varies with x and y position and is described from the anchor center as a linear function and a nonlinear curvature component according to the following equation:

[0037] z(x,y)=gap+R(x,y)+Curv(NL(x,y)); where gap=ideal initial parallel gap, R(x,y) is the rotation, and Curv(NL(x,y)) is the mathematical description of the curvature, which can be a polynomial, trigonometric series, power series, or similar nonlinear function or series.

[0038] Figure 1 A cross-sectional view 100 of ideal and non-ideal MEMS sensor conditions according to one embodiment is illustrated. In one embodiment, the MEMS sensor includes at least a MEMS device, a sensing reference plane, and an anchor coupling the MEMS device to the sensing reference plane. In FIG100, an ideal condition 102 shows a parallel alignment between the MEMS device and the sensing reference plane. In FIG100, a first non-ideal condition 104 shows a deviation from the parallel alignment due to an undesirable linear tilt of at least one surface (as shown in the MEMS device and / or the sensing reference plane). In FIG100, a second non-ideal condition 106 shows a deviation from the parallel alignment due to an undesirable curvature of at least one surface (as shown in the sensing reference plane and / or the MEMS device).

[0039] Systems and methods according to the disclosed subject matter provide a MEMS sensor having a sensing reference plane including a pattern of sensing elements (electrodes) to improve offset suppression. The pattern of sensing elements may be a plurality of electrode patterns to reduce offsets caused by deviations from parallel alignment between the MEMS device and the sensing reference plane. The sensing reference plane is connected to the MEMS device via an anchor. The MEMS device includes a spring connected between the anchor and a proof mass. Each electrode of the plurality of electrode patterns is located on the sensing reference plane, such as a complementary metal oxide semiconductor substrate. In a MEMS device / complementary metal oxide semiconductor substrate die configuration, the proof mass and one of the plurality of electrodes located on the complementary metal oxide semiconductor substrate (or sensing reference plane) form a parallel plate capacitor.

[0040] To more fully describe the features of the disclosed subject matter, reference is now made to the following description taken in conjunction with the accompanying drawings.

[0041] Figure 2A Figure 200 shows a cross-sectional view 202 of a substrate portion of a MEMS sensor having a pattern of sensing elements according to an embodiment. The cross-sectional view 202 shows the MEMS sensor including a MEMS device 250 coupled to a sensing reference plane 260 through an anchor 210, thereby creating a gap between the MEMS device 250 and the sensing reference plane 260. In the cross-sectional view 202, AA depicts the height of the sensing reference plane 260. In one embodiment, the MEMS device 250 is any one of a MEMS structure and a MEMS accelerometer.

[0042] Figure 2B FIG. 270 shows a top view 204 of a substrate portion of a MEMS sensor having a pattern of sensing elements according to an embodiment. The top view 204 shows a top view of AA resulting in a top surface of the sensing element of the pattern including positive and negative electrodes. The top view 204 includes an anchor 210 of the MEMS sensor, positive electrodes 220, 222, 224, and 226, negative electrodes 230, 232, 234, and 236, and four polarity antisymmetry axes 240, 242, 244, and 246 represented by dashed lines. Figure 2A and Figure 2B In FIG. 2 , the shape of the anchor 210 is circular to correspond to the shape of the sensing elements of the pattern which are also circular.

[0043] In one embodiment, the MEMS device 250 includes a spring connected between the anchor 210 and the proof mass. The proof mass moves in the Z axis under an external force, which includes but is not limited to acceleration, magnetism, Coriolis, pressure, and many other external forces. The sensing elements of the pattern include alternating positive and negative electrodes 220-226 and 230-236, and are connected between the MEMS device 250 and the sensing reference plane 260. The positive electrode sensing elements 220-226 detect positive motion, and the negative electrode sensing elements 230-236 detect negative motion. In one embodiment, the shape of the electrode sensing elements 220-226 and 230-236 is an annular sector.

[0044] Figure 2C FIG. 2 shows a MEMS device of a MEMS sensor according to an embodiment. Figure 2C In the MEMS device, a device similar to Figure 2AThe MEMS device 250 is a MEMS Z-axis accelerometer. In one embodiment, the MEMS device 250 further includes a first set of springs (260-263) and a second set of springs (270-273), sensing masses 280-283, and a detection mass 290. The sensing masses 280-283 are connected to the anchor 210 through the second set of springs 270-273, respectively. The sensing masses 280-283 are connected to the detection mass 290 through the first set of springs 260-263, respectively. The sensing masses 280-283 are detected by the positive electrodes 220, 222, 224, 226 and the negative electrodes 230, 232, 234, 236, respectively.

[0045] In one embodiment, the MEMS device 250 causes the proof mass 290 to move in the negative (-) Z-axis direction under positive (+) Z-axis out-of-plane acceleration. The deflected proof mass 290 pushes the first set of springs 260-263, thereby causing the sense masses 280-283 to rotate around the second set of springs 270-273, respectively. This causes the gap between the positive electrodes 220, 222, 224, and 226 and each sense mass 280-283 to decrease, and also causes the gap between the negative electrodes 230, 232, 234, and 236 and the sense masses 280-283 to increase.

[0046] In one embodiment, the behavior of the MEMS device 250 under non-ideal conditions is similar to the behavior of the MEMS devices 104 and 106 described above. The electrode pattern 204 has the characteristics of sensing the deflection of the MEMS device 250 under Z-axis acceleration, but also rejecting Figure 1 The non-ideal motion of MEMS device 250 is described in detail with reference to MEMS devices 104 and 106 .

[0047] In the present embodiment, the electrode sensing elements 220-226 and 230-236 form a differential sensing scheme. For example, the differential sensing scheme reduces the gap above the sensing elements 220, 222, 224 and 226 and increases the gap above the sensing elements 230, 232, 234 and 236. Therefore, motion is detected only when the gap between each pair of positive electrode sensing elements 220-226 and negative electrode sensing elements 230-236 and the micro-electromechanical system device 250 changes due to the movement of the detection mass. Therefore, using the differential architecture of the sensing elements (electrodes) of the pattern, the detection mass moves in a path that causes detectable motion. The center of each sensing element 220-226 and 230-236 has a common distance from the center of the anchor 210. As previously described, the sensing elements 220-226 and 230-236 have four polarity anti-symmetric axes 240-246. In another embodiment, the pattern of sensing elements is designed to have three or more axes of symmetry.

[0048] exist Figure 2B In the top view 204 of FIG. 2 , each of the positive sense elements (electrodes) 220-226 has the same distance from the center of the anchor to the center of the electrode as the corresponding negative sense element (electrode) 230-236. Therefore, any equal movement on either side of the axis will result in equal gap movement for the positive and negative electrodes, since no net output is produced when the positive and negative electrodes move together.

[0049] Thus, perpendicular to axis 240, negative sense element 236 has the same distance as positive sense element 222 (thus electrode 236 corresponds to electrode 222 perpendicular to axis 240), negative sense element 230 has the same distance as positive sense element 220 (thus electrode 230 corresponds to electrode 220 perpendicular to axis 240), negative sense element 232 has the same radius as positive sense element 226 (thus electrode 232 corresponds to electrode 226 perpendicular to axis 240), and negative sense element 234 has the same distance as positive sense element 224 (thus electrode 234 corresponds to electrode 224 perpendicular to axis 240). Any motion, rotation, curvature, or any combination thereof centered perpendicular to axis 240 causes positive sense elements 220-226 to move in a manner similar to negative sense elements 230-236, thereby producing no net output and zero offset in a differential sensing architecture.

[0050] exist Figure 2BIn top view 204 of FIG. 2 , each of positive sense elements (electrodes) 220-226 has the same distance from a corresponding negative sense element (electrode) 230-236 perpendicular to axis 242. In other words, each corresponding positive and negative electrode has the same distance from any point to axis 242. Moreover, the distance from the center of each positive sense element 220-226 to the center of anchor 210 is the same as the distance from the center of each corresponding negative sense element 230-236 to the center of anchor 210.

[0051] Thus, perpendicular to axis 242, negative sense element 230 has the same distance as positive sense element 226 (thus electrode 230 corresponds to electrode 226 perpendicular to axis 242), negative sense element 236 has the same distance as positive sense element 220 (thus electrode 236 corresponds to electrode 220 perpendicular to axis 242), negative sense element 232 has the same distance as positive sense element 224 (thus electrode 232 corresponds to electrode 224 perpendicular to axis 242), and negative sense element 234 has the same distance as positive sense element 222 (thus electrode 234 corresponds to electrode 222 perpendicular to axis 242). Any motion, rotation, curvature, or any combination thereof centered about axis 242 causes positive sense elements 220-226 to move in a manner similar to negative sense elements 230-236, thereby producing no net output and zero offset in a differential sensing architecture.

[0052] exist Figure 2B In top view 204 of FIG. 2 , each of positive sense elements (electrodes) 220-226 has the same distance from a corresponding negative sense element (electrode) 230-236 perpendicular to axis 244. In other words, each corresponding positive and negative electrode has the same distance from any point to axis 244. Additionally, the distance from the center of each positive sense element 220-226 to the center of anchor 210 is the same as the distance from the center of each corresponding negative sense element 230-236 to the center of anchor 210.

[0053] Thus, perpendicular to axis 244, negative sense element 230 has the same distance as positive sense element 224 (thus electrode 230 corresponds to electrode 224 perpendicular to axis 244), negative sense element 236 has the same distance as positive sense element 226 (thus electrode 236 corresponds to electrode 226 perpendicular to axis 244), negative sense element 232 has the same distance as positive sense element 222 (thus electrode 232 corresponds to electrode 222 perpendicular to axis 244), and negative sense element 234 has the same distance as positive sense element 220 (thus electrode 234 corresponds to electrode 220 perpendicular to axis 244). Any motion, rotation, curvature, or any combination thereof centered about axis 244 causes positive sense elements 220-226 to move in a manner similar to negative sense elements 230-236, thereby producing no net output and zero offset in a differential sensing architecture.

[0054] exist Figure 2B In top view 204 of FIG. 2 , each of positive sense elements (electrodes) 220-226 has the same distance from a corresponding negative sense element (electrode) 230-236 perpendicular to axis 246. In other words, each corresponding positive and negative electrode has the same distance from any point to axis 246. Furthermore, the distance from the center of each positive sense element 220-226 to the center of anchor 210 is the same as the distance from the center of each corresponding negative sense element 230-236 to the center of anchor 210.

[0055] Thus, perpendicular to axis 246, negative sense element 230 has the same distance as positive sense element 222 (so electrode 230 corresponds to electrode 222 perpendicular to axis 246), negative sense element 236 has the same distance as positive sense element 224 (so electrode 236 corresponds to electrode 224 perpendicular to axis 246), negative sense element 232 has the same distance as positive sense element 220 (so electrode 232 corresponds to electrode 220 perpendicular to axis 246), and negative sense element 234 has the same distance as positive sense element 226 (so electrode 234 corresponds to electrode 226 perpendicular to axis 246). Any motion, rotation, curvature, or any combination thereof centered about axis 246 causes positive sense elements 220-226 to move in a manner similar to negative sense elements 230-236, thereby producing no net output and zero offset in a differential sensing architecture.

[0056] Figure 3AA top view 300 of a MEMS sensor having a pattern of sensing elements and corresponding MEMS structures according to another embodiment is shown. The top view 300 shows the top surface of the patterned sensing element including positive and negative electrodes. The top view 300 includes an anchor 310 of the MEMS sensor, positive electrodes 320, 322, 324, and 326, negative electrodes 330, 332, 334, and 336, and four polarity antisymmetric axes 340, 342, 344, and 346 represented by dashed lines. Figure 3A In FIG. 3 , the shape of anchor 310 is square to correspond to the shape of the sensing elements of the pattern which are also square.

[0057] In one embodiment, Figure 3A The MEMS sensor includes a MEMS device coupled to a sensing reference plane via an anchor 310, thereby creating a gap between the MEMS device and the sensing reference plane. The MEMS device includes a spring connected between the anchor 310 and the proof mass. The proof mass moves in the Z axis in response to an external force, including but not limited to an external force of acceleration, magnetic field, Coriolis force or pressure. The sensing element of the pattern includes alternating positive and negative electrodes 320-326 and 330-336 on the sensing reference plane.

[0058] In the present embodiment, sensing elements 320-326 and 330-336 form a differential sensing architecture. Therefore, motion is detected only when the gap between each pair of positive electrode sensing elements 320-326 and negative electrode sensing elements 330-336 and the micro-electromechanical system device changes due to the movement of the detection mass. When sensing acceleration, for each electrode pair (e.g., for positive sensing electrode 320 and negative sensing electrode 330), the detection mass moves the same amount in the same direction. Therefore, using the differential sensing architecture of the sensing elements (electrodes) of the pattern, the detection mass moves in a shape that causes detectable motion. The center of each of the sensing elements 320-326 and 330-336 has a common distance from the center of the anchor 310. As previously described, the sensing elements 320-326 and 330-336 have four axes 340-346 of anti-polarity symmetry. In another embodiment, the sensing elements of the pattern are designed to have three or less and five or more axes of symmetry.

[0059] exist Figure 3AIn top view 300 of FIG. 3 , each of positive sense elements (electrodes) 320-326 has the same distance from a corresponding negative sense element (electrode) 330-336 perpendicular to axis 340. In other words, each corresponding positive and negative electrode has the same distance from any point to axis 340. Moreover, the distance from the center of each positive sense element 320-326 to the center of anchor 310 is the same as the distance from the center of each corresponding negative sense element 330-336 to the center of anchor 310.

[0060] Thus, perpendicular to axis 340, negative sense element 336 has the same distance as positive sense element 326 (thus electrode 336 corresponds to electrode 326 perpendicular to axis 340), negative sense element 330 has the same distance as positive sense element 324 (thus electrode 330 corresponds to electrode 324 perpendicular to axis 340), negative sense element 332 has the same distance as positive sense element 322 (thus electrode 332 corresponds to electrode 322 perpendicular to axis 340), and negative sense element 334 has the same distance as positive sense element 320 (thus electrode 334 corresponds to electrode 320 perpendicular to axis 3440). Any anchor rotation, curvature, or any combination thereof centered perpendicular to axis 340 causes positive sense elements 320-326 to move in a similar manner as negative sense elements 330-336, thereby producing no net output and zero offset in a differential sensing architecture.

[0061] exist Figure 3A In top view 300 of FIG. 3 , each of positive sense elements (electrodes) 320-326 has the same distance from a corresponding negative sense element (electrode) 330-336 perpendicular to axis 342. In other words, each corresponding positive and negative electrode has the same distance from any point to axis 342. Additionally, the distance from the center of each positive sense element 320-326 to the center of anchor 310 is the same as the distance from the center of each corresponding negative sense element 330-336 to the center of anchor 310.

[0062] Thus, perpendicular to axis 342, negative sense element 330 has the same distance as positive sense element 326 (so electrode 330 corresponds to electrode 326 perpendicular to axis 342), negative sense element 336 has the same distance as positive sense element 320 (so electrode 336 corresponds to electrode 320 perpendicular to axis 342), negative sense element 332 has the same distance as positive sense element 324 (so electrode 332 corresponds to electrode 324 perpendicular to axis 342), and negative sense element 334 has the same distance as positive sense element 322 (so electrode 334 corresponds to electrode 322 perpendicular to axis 342). Any motion, rotation, curvature, or any combination thereof centered about axis 342 causes positive sense elements 320-326 to move in a manner similar to negative sense elements 330-336, resulting in no net output and zero offset in a differential sensing architecture.

[0063] exist Figure 3A In top view 300 of FIG. 3 , each of positive sense elements (electrodes) 320-326 has the same distance from a corresponding negative sense element (electrode) 330-336 perpendicular to axis 344. In other words, each corresponding positive and negative electrode has the same distance from any point to axis 344. Additionally, the distance from the center of each positive sense element 320-326 to the center of anchor 310 is the same as the distance from the center of each corresponding negative sense element 330-336 to the center of anchor 310.

[0064] Thus, perpendicular to axis 344, negative sense element 330 has the same distance as positive sense element 324 (so electrode 330 corresponds to electrode 320 perpendicular to axis 344), negative sense element 336 has the same distance as positive sense element 326 (so electrode 336 corresponds to electrode 326 perpendicular to axis 344), negative sense element 332 has the same distance as positive sense element 322 (so electrode 332 corresponds to electrode 322 perpendicular to axis 344), and negative sense element 334 has the same distance as positive sense element 320 (so electrode 334 corresponds to electrode 320 perpendicular to axis 344). Any motion, rotation, curvature, or any combination thereof centered about axis 344 causes positive sense elements 320-326 to move in a manner similar to negative sense elements 330-336, thereby producing no net output and zero offset in a differential sensing architecture.

[0065] exist Figure 3AIn top view 300 of FIG. 346 , each of positive sense elements (electrodes) 320-326 has the same distance from a corresponding negative sense element (electrode) 330-336 perpendicular to axis 346. In other words, each corresponding positive and negative electrode has the same distance from any point to axis 346. Moreover, the distance from the center of each positive sense element 320-326 to the center of anchor 310 is the same as the distance from the center of each corresponding negative sense element 330-336 to the center of anchor 310.

[0066] Thus, perpendicular to axis 346, negative sense element 330 has the same distance as positive sense element 322 (so electrode 330 corresponds to electrode 322 perpendicular to axis 346), negative sense element 336 has the same distance as positive sense element 324 (so electrode 336 corresponds to electrode 324 perpendicular to axis 346), negative sense element 332 has the same distance as positive sense element 320 (so electrode 332 corresponds to electrode 320 perpendicular to axis 346), and negative sense element 334 has the same distance as positive sense element 326 (so electrode 334 corresponds to electrode 326 perpendicular to axis 346). Any motion, rotation, curvature, or any combination thereof centered about axis 346 causes positive sense elements 320-326 to move in a manner similar to negative sense elements 330-336, thereby producing no net output and zero offset in a differential sensing architecture.

[0067] Figure 3B FIG. 3 shows a MEMS accelerometer structure 350 of a MEMS sensor using an electrode pattern according to an embodiment. The MEMS accelerometer structure 350 is similar to Figure 2A FIG. 2 is a schematic diagram of a MEMS device 250 in FIG. 2. Under out-of-plane acceleration of the MEMS sensor, proof mass 360 rotates in the negative RX direction about torsion springs 370 and 375. This causes the gap between positive sense electrodes 320 and 322 to decrease and the gap between negative sense electrodes 334 and 332 to increase relative to the sensing plane. In one embodiment, electrodes 324, 326, 330, and 336 are rigidly connected to the anchor and do not experience gap changes due to acceleration of the MEMS sensor. A signal processor combines electrodes 320-326 and 330-336 to output a signal proportional to the sensor acceleration.

[0068] exist Figure 3B In the case of a MEMS sensor anchor rotation, Figure 1 In the first non-ideal condition 104, all electrodes 320-326 and 330-336 are connected to the anchor and are connected in a manner similar to Figure 3AThe group of plates described in FIG. 1 moves about axes 340, 344, and 346. The signal processor combines electrodes 320-326 and 330-336 and produces no net output if the anchor rotation or the sense reference plane curvature is centered about axes 340-346. In this embodiment, electrodes 320, 322, 332, and 334 are used to detect the acceleration of the MEMS sensor, while electrodes 320-326, 330-336 are used to suppress the offset caused by the anchor rotation or the sense reference plane curvature.

[0069] Figure 4 A top view 400 of a MEMS sensor having a pattern of sensing elements according to another embodiment is shown. The top view 400 shows the top surface of the sensing element of the pattern including positive and negative electrodes. The top view 400 includes an anchor 410 of the MEMS sensor, positive electrodes 420, 422, and 424, negative electrodes 430, 432, and 434, and three axes of anti-polarity symmetry 440, 442, and 444 represented by dashed lines. Figure 4 , the shape of anchor 410 is circular to correspond to the shape of the sensing elements of the pattern, which are also circular.

[0070] In one embodiment, Figure 4 The MEMS sensor includes a MEMS device coupled to a sensing reference plane via an anchor 410, thereby creating a gap between the MEMS device and the sensing reference plane. The MEMS device includes a spring connected between the anchor 410 and the detection mass. The detection mass moves in the Z axis under the action of an external force, which includes but is not limited to acceleration, magnetic field, Coriolis force, pressure and many other external forces. The sensing elements of the pattern include alternating positive and negative electrodes 420-424 and 430-434, and are connected between the MEMS device and the sensing reference plane. The positive electrode sensing elements 420-424 sense positive motion and the negative electrode sensing elements 430-434 sense negative motion.

[0071] In this embodiment, the sensing elements 420-424 and 430-434 form a differential sensing architecture. Therefore, motion is detected only when the positive electrode sensing element 420-424 moves relative to the negative electrode sensing element 430-434. Using the differential sensing architecture of the sensing elements (electrodes) of this pattern, the proof mass moves in a shape that causes detectable motion. The center of each sensing element 420-424 and 430-434 has a common radius with the center of the anchor 410. As previously described, the sensing elements 420-424 and 430-434 have three axes 440-444 of anti-polarity symmetry.

[0072] exist Figure 4In top view 400 of FIG. 4 , each of positive sense elements (electrodes) 420-424 has the same distance from a corresponding negative sense element (electrode) 430-434 perpendicular to axis 440. In other words, each corresponding positive and negative electrode has the same distance from any point to axis 440. Additionally, the distance from the center of each positive sense element 420-424 to the center of anchor 410 is the same as the distance from the center of each corresponding negative sense element 430-434 to the center of anchor 410.

[0073] Thus, perpendicular to axis 440, negative sense element 430 has the same distance as positive sense element 420 (thus electrode 430 corresponds to electrode 420 perpendicular to axis 440), negative sense element 432 has the same distance as positive sense element 424 (thus electrode 432 corresponds to electrode 424 perpendicular to axis 440), and negative sense element 434 has the same distance as positive sense element 422 (thus electrode 434 corresponds to electrode 422 perpendicular to axis 440). Any motion, rotation, curvature, or any combination thereof centered about axis 440 causes positive sense elements 420-424 to move in a manner similar to negative sense elements 430-434, thereby producing no net output and zero offset in a differential sensing architecture.

[0074] exist Figure 4 In top view 400 of FIG. 4 , each of positive sense elements (electrodes) 420-424 has the same distance from a corresponding negative sense element (electrode) 430-434 perpendicular to axis 442. In other words, each corresponding positive and negative electrode has the same distance from any point to axis 442. Moreover, the distance from the center of each positive sense element 420-424 to the center of anchor 410 is the same as the distance from the center of each corresponding negative sense element 430-434 to the center of anchor 410.

[0075] Thus, perpendicular to axis 442, negative sense element 434 has the same distance as positive sense element 420 (thus electrode 434 corresponds to electrode 420 perpendicular to axis 442), negative sense element 432 has the same distance as positive sense element 422 (thus electrode 432 corresponds to electrode 422 perpendicular to axis 442), and negative sense element 430 has the same distance as positive sense element 424 (thus electrode 430 corresponds to electrode 424 perpendicular to axis 442). Any motion, rotation, curvature, or any combination thereof centered about axis 442 causes positive sense elements 420-424 to move in a manner similar to negative sense elements 430-434, resulting in no net output and zero offset in a differential sensing architecture.

[0076] exist Figure 4In top view 400 of FIG. 4 , each of positive sense elements (electrodes) 420-424 has the same distance from a corresponding negative sense element (electrode) 430-434 perpendicular to axis 444. In other words, each corresponding positive and negative electrode is the same distance from any point to axis 444. Moreover, the distance from the center of each positive sense element 420-424 to the center of anchor 410 is the same as the distance from the center of each corresponding negative sense element 430-434 to the center of anchor 410.

[0077] Thus, perpendicular to axis 444, negative sense element 434 has the same distance as positive sense element 424 (thus electrode 434 corresponds to electrode 424 perpendicular to axis 444), negative sense element 430 has the same distance as positive sense element 422 (thus electrode 430 corresponds to electrode 422 perpendicular to axis 444), and negative sense element 432 has the same distance as positive sense element 420 (thus electrode 432 corresponds to electrode 420 perpendicular to axis 444). Any motion, rotation, curvature, or any combination thereof centered about axis 444 causes positive sense elements 420-424 to move in a manner similar to negative sense elements 430-434, resulting in no net output and zero offset in a differential sensing architecture.

[0078] Figure 5 A top view 500 of a MEMS sensor having a pattern of sensing elements according to another embodiment is shown. The top view 500 shows the top surface of the sensing element including two independent patterns of positive and negative electrodes. The top view 500 includes an anchor 510 of the MEMS sensor, positive electrodes 520, 522, 524, and 526 in a first pattern, negative electrodes 530, 532, 534, and 536 in a first pattern, positive electrodes 570, 572, 574, and 576 in a second pattern, negative electrodes 560, 562, 564, and 566 in a second pattern, and four axes of anti-polarity symmetry 540, 542, 544, and 546 represented by dashed lines. Figure 5 In the embodiment, the shape of anchor 510 is circular to correspond to the shape of the sensing elements of the two independent patterns, which are also circular. In another embodiment, the sensing elements of the two patterns work in conjunction with each other and are therefore interdependent.

[0079] exist Figure 5 In the first pattern, the sensing elements include alternating positive electrodes 520-526 and negative electrodes 530-536, similar to Figure 2B The sensing elements (220-226 and 230-236) of the pattern in the top view 204 of FIG. 2 work in the same manner. In addition, the sensing elements of the second pattern include alternating positive electrodes 570-576 and negative electrodes 560-566, which work in the same manner as Figure 2BThe pattern of sensing elements (220-226 and 230-236) in top view 204 is similar, but with additional sensitivity levels added to further reduce offset using a dual differential sensing scheme. One of ordinary skill in the art will readily appreciate that the electrodes of the sensing elements of the first and / or second patterns may be reorganized and remain within the scope of the disclosed subject matter.

[0080] Figure 6 A top view 600 of a MEMS sensor having a pattern of sensing elements according to another embodiment is shown. The top view 600 shows the top surface of a pattern of sensing elements including positive and negative electrodes in four quadrants divided by two axes 640 (y-axis) and 642 (x-axis) represented by dashed lines. The top view 600 includes an anchor 610 of the MEMS sensor, positive electrodes 620-621 and negative electrodes 630-631 in the first quadrant (upper left), positive electrodes 622-623 and negative electrodes 632-633 in the second quadrant (upper right), positive electrodes 624-625 and negative electrodes 634-635 in the third quadrant (lower left), and positive electrodes 626-627 and negative electrodes 636-637 in the fourth quadrant (lower right).

[0081] exist Figure 6 6, positive electrodes 620-627 have a "W" shape centered at the center of anchor 610, and negative electrodes 630-637 have an "M" shape centered at the center of anchor 610. Negative electrodes 630-637 are interwoven with positive electrodes 620-627 to form the sensing element of the pattern, thereby reducing offset caused by adverse conditions.

[0082] because Figure 6For the sensing elements of this pattern, any rotation about axis 642 produces no net output and zero offset because the positive electrodes 620-623 share the same distance (distance defined as the perpendicular distance between the center of the electrode and the axis) as the negative electrodes 630-633, and the positive electrodes 624-627 share the same distance as the negative electrodes 634-637. Any curvature along axis 642 produces no net output and zero offset because the distances from the positive electrodes 620-623 are the same as the distances from the negative electrodes 630-633, and the distances from the positive electrodes 624-627 are the same as the distances from the negative electrodes 634-637. Similarly, any curvature along axis 640 will not produce a net output and zero offset because the positive electrodes 620-621 and 624-625 are the same distance from the negative electrodes 630-631 and 634-635, and the positive electrodes 622-623 and 626-627 are the same distance from the negative electrodes 632-633 and 636-637; and any rotation perpendicular to axis 640 will not produce a net output and zero offset because the positive electrodes 620-621 and 624-625 share the same distance with the negative electrodes 630-631 and 634-635, and the positive electrodes 622-623 and 626-627 share the same distance with the negative electrodes 632-633 and 636-637.

[0083] In one embodiment, electrodes 630 and 631 are combined into one electrode, electrodes 624 and 625 are combined into one electrode, electrodes 632 and 633 are combined into one electrode, and electrodes 626 and 627 are combined into one electrode.

[0084] In a first embodiment, a MEMS sensor includes a sensing reference plane, at least one anchor coupled to the sensing reference plane, and at least one proof mass coupled to the at least one anchor, wherein one of the at least one proof mass moves under an external excitation. The MEMS sensor further includes a pattern of sensing elements (or sensing electrodes) located on the sensing reference plane or coupled between the sensing reference plane and the at least one proof mass to detect the movement of the at least one proof mass on a normal to the sensing reference plane, wherein the sensing elements of the pattern share at least three axes of polarity antisymmetry. The MEMS sensor also includes a signal processing circuit to combine the sensing elements of the pattern to provide an output proportional to the external excitation. In one embodiment, the output is the difference between a positive sensing element and a negative sensing element of the sensing elements of the pattern.

[0085] In one embodiment, at least one proof mass is coupled to at least one anchor via at least one spring. In one embodiment, the sensing elements of the pattern share any of one, two, three, four, and five or more polarity-antisymmetric axes. In one embodiment, the center of mass of each sensing element has a common distance from the center of at least one anchor. In one embodiment, the sensing elements of the pattern include sensing electrodes, forming a variable capacitor between each electrode and at least one proof mass.

[0086] In one embodiment, the sensing electrodes of the pattern include alternating positive electrodes and negative electrodes, and in another embodiment, the positive electrodes and negative electrodes are not alternating, but may include two or more positive electrodes and / or two or more negative electrodes adjacent to each other. In one embodiment, the sensing electrodes of the pattern include alternating at least three positive sensing electrodes and at least three negative sensing electrodes.

[0087] In one embodiment, each negative sensing element / electrode has the same area as each positive sensing element / electrode, and in another embodiment, each negative sensing element / electrode has substantially the same electrode area as each positive sensing element / electrode. In one embodiment, the sensing electrodes are any one of capacitive sensing, piezoresistive sensing, and magnetic sensing electrodes. In one embodiment, the center of each sensing electrode is located on the perimeter of any one of a circle, rectangle, square, hexagon, octagon, and other polygons, and the sensing electrode itself is any one of a circle, rectangle, square, hexagon, octagon, annular sector, and polygon.

[0088] In one embodiment, the MEMS sensor further includes a second pattern of sensing elements on the sensing reference plane to detect motion of at least one proof mass relative to the sensing reference plane, wherein each sensing element of the second pattern of sensing elements shares at least three polarity-antisymmetric axes, and further wherein the centroid of each sensing element of the second pattern of sensing elements shares a second common distance with the center of at least one anchor. In another embodiment, the MEMS sensor includes a plurality of sensing element patterns coupled on top of or adjacent to each other to further reduce offset.

[0089] In a second embodiment, a sensing reference plane of the MEMS sensor is divided by two axes (a first axis and a second axis), forming four quadrants on the sensing reference plane, and the sensing elements of the pattern include at least three sensing elements in each of the four quadrants to detect the movement of at least one detection mass relative to the sensing reference plane. In this embodiment, the MEMS sensor includes at least one anchor coupled to the sensing reference plane and at least one detection mass coupled to the at least one anchor, wherein one of the at least one detection mass moves under external excitation. Each of the four quadrants includes two external sensing electrodes having a first polarity and two internal sensing electrodes having a second polarity. The first polarity is opposite to the second polarity, and there is polarity antisymmetry in at least three sensing elements in each of the four quadrants.

[0090] In one embodiment, in each of the four quadrants, the closest sensing element and the farthest sensing element relative to one of the first axis or the second axis are of a first polarity, and between the closest sensing element and the farthest sensing element, there is at least one sensing element of a second polarity. In one embodiment, the first polarity is opposite to the second polarity, and there is polarity antisymmetry in the four quadrants about at least one of the first axis or the second axis. In one embodiment, the center of at least one anchor coincides with the intersection of the first axis and the second axis. In one embodiment, the center of mass of at least three sensing elements in each of the four quadrants have a common distance from at least one of the first axis or the second axis. In one embodiment, the sensing element area between the first and second polarities is substantially the same.

[0091] In one embodiment, the pattern of sensing elements includes a first pattern and a second pattern, wherein the first pattern is an M-shaped polarity pattern centered on at least one anchor, and the second pattern is a W-shaped polarity pattern centered on at least one anchor. In one embodiment, at least a portion of at least four sensing elements in each of the four quadrants are in a straight line, and in another embodiment, at least a portion of at least four sensing elements in each of the four quadrants are in a non-straight line and / or direction.

[0092] Sensing elements with opposite polarities among the at least four sensing elements share a common distance from one of the symmetry lines. In one embodiment, the shape of the at least four sensing elements is any one of a circle, a rectangle, a square, a hexagon, an octagon, and a polygon. In another embodiment, the sensing reference plane is not divided into any quadrants, and the sensing elements of the pattern include two groups of at least four sensing elements, which are located on the same axis and on opposite sides of at least one anchor.

[0093] As described above, the system (MEMS sensor) and method according to the disclosed subject matter utilizes multiple patterns of sensing elements (electrodes) on a sensing reference plane to reduce the adverse effects of deviations in parallel alignment between the MEMS device of the MEMS sensor and the sensing reference plane that occur due to various undesirable forces. Deviations in parallel alignment result in offsets, and each of the multiple patterns does not produce a net output, and offset suppression is improved (providing zero or reduced offsets) by utilizing multiple sensing architectures that counteract detected rotational and / or curvature type forces.

[0094] Additionally, according to other described embodiments, the subject disclosure provides MEMS accelerometer structures and apparatus configured to reduce undesired signals generated by deformation of a surface or substrate to which the MEMS structure is anchored, which can improve the offset stability of out-of-plane sensing MEMS accelerometers. For example, as described above, in MEMS inertial sensors, such as capacitive MEMS accelerometers, offsets (undesired output signals in the absence of applied external acceleration) are primarily generated by deformation of the substrate that constitutes the MEMS device. In the exemplary case of a MEMS accelerometer that is sensitive to acceleration in an out-of-plane direction, the goal of not generating any signal when substrate deformation occurs can be addressed in a variety of ways. The disclosed subject matter provides further non-limiting embodiments that employ exemplary aspects of suppressing such undesired signals.

[0095] The disclosed subject matter provides a planar MEMS structure that can be suspended above a planar surface associated with a MEMS substrate via anchor points, as described above with respect to Figure 2A-2B Description. In a non-limiting aspect, the exemplary MEMS structures and devices may include a reference MEMS structure to measure anchor deformation of the sensing MEMS structure, as further described below. In a further non-limiting aspect, the reference MEMS structure and the sensing MEMS structure may be connected via one or more springs (e.g., sensing springs), which may be collectively referred to as elastic coupling, as further described herein. In another non-limiting aspect, the exemplary sensing MEMS structure as described herein may move with the exemplary reference MEMS structure in the presence of device deformation, and the exemplary sensing MEMS structure further undergoes movement relative to the exemplary reference MEMS structure in response to external forces on the exemplary MEMS structure and device, as further described herein.

[0096] In the exemplary MEMS accelerometers described herein, the exemplary sensing MEMS structures can be configured to generate a desired signal in response to an external acceleration along a sensing axis. In a further non-limiting embodiment of a tilted Z-axis accelerometer, the further motion is a tilt motion about an axis where the sensing spring or elastic coupling is located.

[0097] In further non-limiting aspects, the described embodiments may be characterized by a capacitive sensing architecture, wherein a first plate of a capacitor may be configured to be located on a surface of a respective MEMS planar structure, and wherein an opposing plate of the capacitor may be configured to be located on a plane parallel to the surface of the first plate (e.g., on or adjacent to a MEMS substrate). Thus, as further described herein, electrodes on each MEMS planar structure may be configured to convert an external load applied to an exemplary MEMS structure and device into capacitive information, wherein electrodes on an exemplary reference MEMS structure may be configured to compensate for undesired signals that would otherwise be generated. According to various non-limiting embodiments, the exemplary electrodes may be arranged in a circular manner, as further described herein.

[0098] In the embodiment, according to various non-limiting embodiments, all electrodes can have the same area and the same radius from the anchor center, which is located at the center of the electrode pattern. According to further non-limiting aspects, the center of the electrode pattern corresponds to the center at which the exemplary reference MEMS structure is anchored.

[0099] In other exemplary embodiments, the exemplary reference MEMS structure and the exemplary sensing MEMS structure may have alternating interdigitated arms or annular sectors in other non-limiting aspects. In exemplary embodiments, the number of arms or annular sectors of the exemplary reference MEMS structure and the exemplary sensing MEMS structure are different, wherein, in further non-limiting aspects, one of the exemplary reference MEMS structure and the exemplary sensing MEMS structure has at least two or more arms or annular sectors, and the number of arms or annular sectors of the exemplary reference MEMS structure may be independent of the number of electrodes.

[0100] According to various embodiments described herein, the minimum number of electrodes may be 6, but may be increased in increments of only 4, where the number (6, 10, 14, 18 ...) may allow the exemplary MEMS structure or device to be completely symmetrical about an axis orthogonal to the sensing spring or elastic coupling axis. In a further non-limiting embodiment, the exemplary reference MEMS structure may be symmetrical about the axis where the sensing spring (or elastic coupling) is located. As further described below, depending on the number of electrodes (n), the reference structure may be symmetrical about up to ((n+2) / 4) axes.

[0101] According to further non-limiting embodiments, the exemplary sensing MEMS structure can be completely symmetrical about an axis orthogonal to the spring or elastic coupling axis, and in a further non-limiting aspect, can further be composed of a balanced sensing structure, which can be symmetrical about the spring or elastic coupling axis, and an unbalanced sensing structure, which can have a unique symmetry axis orthogonal to the spring or elastic coupling axis. According to various non-limiting embodiments described herein, the exemplary MEMS structure or device including a circular arrangement of electrodes can completely suppress the rigid anchor tilt along the n / 2 axis.

[0102] therefore, Figure 7 Various aspects of another non-limiting embodiment of a reference MEMS structure for an exemplary MEMS device 700 described herein are depicted. In non-limiting aspects, the exemplary MEMS device may include an exemplary reference MEMS structure 702 located in a plane above a MEMS substrate (not shown), as described above with respect to Figure 2A-2B In another non-limiting aspect, the exemplary reference MEMS structure 702 can be anchored (eg, via anchors 704) to a MEMS substrate.

[0103] Figure 8 Further non-limiting aspects of a sensing MEMS structure 802 for another exemplary embodiment are depicted. For example, the exemplary MEMS device 700 may further include an exemplary sensing MEMS structure 802 that may be substantially located in a plane above a MEMS substrate (not shown), as described above with respect to Figure 2A-2B Description of . In another non-limiting aspect, the exemplary sensing MEMS structure 802 can be configured to move in response to an external load (e.g., acceleration) applied to the exemplary MEMS device 700. In a further non-limiting aspect, the exemplary reference MEMS structure 702 and the exemplary sensing MEMS structure 802 can each be configured as respective arm sets (e.g., an arm set of the reference MEMS structure 702 and an arm set of the sensing MEMS structure 802) arranged as interdigitated arm sets extending radially around a center 804 of the reference MEMS structure 702 (e.g., an alternating arrangement of the arm sets of the reference MEMS structure 702 and the sensing MEMS structure 802), for example, with respect to Fig. 9 In another non-limiting aspect of the exemplary MEMS device 700, the sensing MEMS structure 802 includes a balanced sensing mass and an unbalanced sensing mass, for example, as described below with respect to Fig.15 Further description of .

[0104] Fig. 9Further non-limiting aspects of an exemplary elastic coupling 902 according to exemplary embodiments described herein are depicted. For example, the exemplary MEMS device 700 may further include an elastic coupling 902 configured to suspend the sensing MEMS structure 802 above a MEMS substrate (not shown), as described above with respect to Figure 2A-2B Description. Fig. 9 A portion of an exemplary set of interdigitated arms 904 (eg, alternating arrangements of sets of arms of reference MEMS structure 702 and sensing MEMS structure 802 ) extending radially about center 804 of reference MEMS structure 702 is further highlighted.

[0105] Fig. 9 Another non-limiting aspect of the exemplary MEMS device 700 is depicted, wherein the interdigitated arm groups 904 (e.g., alternating arrangements of arm groups of the reference MEMS structure 702 and the sensing MEMS structure 802) can be configured in a circular arrangement around a center 804 of the reference MEMS structure 702. In another non-limiting aspect of the exemplary MEMS device 700, the number of interdigitated arm groups 904 associated with the reference MEMS structure 702 can be different from the number of interdigitated arm groups 904 associated with the sensing MEMS structure 802. For example, according to another non-limiting aspect, the number of interdigitated arm groups 904 associated with the reference MEMS structure 702 can differ from the number of interdigitated arm groups 904 associated with the sensing MEMS structure 802 by two interdigitated arms. In a further non-limiting aspect of the MEMS device 700, the elastic coupling 902 can be oriented substantially along a first symmetry axis of the reference MEMS structure 702 that substantially intersects the center 804 of the reference MEMS structure 702 in a plane above the MEMS substrate, such as described above with respect to Figure 2A-2B described below, and Fig.14 Further description of .

[0106] Fig.10 Various aspects of non-limiting embodiments of sensing electrodes for exemplary devices as described herein are depicted. For example, the exemplary MEMS device 700 can further include a plurality of sensing electrodes 1002 that can be positioned parallel to the sensing MEMS structure 802 (e.g., located on the surface of the respective MEMS planar structure), and which can be configured to sense the position of the sensing MEMS structure 802, as further described herein.

[0107] Fig.11Further aspects of non-limiting embodiments of reference electrodes for the exemplary apparatus are shown. For example, the exemplary MEMS device 700 can further include a plurality of reference electrodes 1102, which can be positioned parallel to the reference MEMS structure 702 (e.g., located on the surface of each MEMS planar structure) and can be configured to sense deformation of the MEMS substrate, the MEMS substrate (not shown), as described above with respect to Figure 1 , 2A - Description of 2B, etc.

[0108] Fig.12 Describes further non-limiting aspects of the exemplary devices described herein. For example, as described above, Fig. 9 A portion of an exemplary interdigitated arm set 904 extending radially around a center 804 of the reference MEMS structure 702 is further highlighted (e.g., an alternating arrangement of arm sets of the reference MEMS structure 702 and the sensing MEMS structure 802). In another non-limiting aspect of the exemplary MEMS device 700, each of the plurality of reference electrodes 1102 and each of the plurality of sensing electrodes 1002 can be associated with a corresponding arm (e.g., one arm of the arm set of the reference MEMS structure 702 or the sensing MEMS structure 802) within the interdigitated arm set 904 (e.g., an alternating arrangement of arm sets of the reference MEMS structure 702 and the sensing MEMS structure 802). Fig.12 As shown, each sense electrode 1002 is associated with a respective arm or annular sector of sense microelectromechanical system structure 802 , while each reference electrode 1102 is associated with a respective arm or annular sector of sense reference structure 702 .

[0109] In another non-limiting aspect of exemplary MEMS device 700, the number of the plurality of reference electrodes 1102 can be different from the number of the plurality of sensing electrodes 1002. In one non-limiting example, in another non-limiting aspect of MEMS device 700, the sum of the plurality of reference electrodes 1102 and the plurality of sensing electrodes 1002 can be at least six. In yet another non-limiting example, the sum is defined by the number of electrodes n, where n is equal to 6+4x, and where x is equal to a selection of zero or a positive integer (e.g., 6, 10, 14, 18, ...).

[0110] According to further non-limiting aspects of exemplary MEMS device 700, one or more of sensing electrode 1002 and reference electrode 1102 can be located below a plane above the MEMS substrate, such as described above with respect to Figure 2A-2B Description, such as Fig.12 As shown, hidden is indicated by dotted lines.

[0111] Fig.13Further non-limiting aspects of exemplary devices for electrode configurations are shown. For example, in another non-limiting aspect of the exemplary MEMS device 700, the reference MEMS structure 702 can be anchored (e.g., through the anchor 704) to a MEMS substrate (not shown) substantially at a center 804 of the reference MEMS structure 702 in a plane above the MEMS substrate, as described above with respect to Figure 2A-2B As described above, Figure 2A-2B Furthermore, in another non-limiting aspect of exemplary MEMS device 700, each of the plurality of sensing electrodes 1002 and each of the plurality of reference electrodes 1102 can be characterized by at least one of having substantially the same area or extending an equivalent radial distance from a center of anchor 704, which can be substantially located near center 804 of reference MEMS structure 702.

[0112] like Fig.13 As depicted, each sensing electrode 1002 associated with a corresponding arm or annular sector of sensing MEMS structure 802 is configured as a corresponding annular sector, while each reference electrode 1102 associated with a corresponding arm or annular sector of sensing reference structure 702 is configured as a corresponding annular sector. Thus, in one non-limiting aspect, the area associated with an annular sector of sensing electrode 1002 can be substantially the same as the area associated with annular sector of reference electrode 1102, without limitation. Fig.13 In another non-limiting aspect depicted in FIG. 1 , each sensing electrode 1002 and each reference electrode 1102 may extend an equivalent radial distance (eg, R ) from the center of the anchor 704. reference 1302 is approximately equal to R sense 1304 ), the center of the anchor 704 can be substantially located near the center 804 of the exemplary reference MEMS structure 702 .

[0113] Fig.14 Various aspects of an exemplary reference MEMS structure 702 are depicted according to further non-limiting embodiments herein. For example, the exemplary MEMS device 700 can further include an exemplary elastic coupling 902 (e.g., an arrangement of one or more springs) that can be oriented substantially along a first symmetry axis 1402 of the reference MEMS structure 702 that substantially intersects a center 804 of the reference MEMS structure 702 in a plane above the MEMS substrate, such as described above with respect to Figure 2A-2B In another non-limiting aspect of the exemplary MEMS device 700, the exemplary reference MEMS structure 702 can be symmetric about a second symmetry axis in a plane above the MEMS substrate, as described above with respect to Figure 2A-2BAs a non-limiting example, the exemplary reference MEMS structure 702 may be symmetric about a second symmetry axis in a plane above the MEMS substrate, as described above with respect to Figure 2A-2B As described, the second symmetry axis is orthogonal to the first symmetry axis 1402 (eg, symmetry axis 1404 ).

[0114] As mentioned above about Fig.12 As described, the sum of the plurality of reference electrodes 1102 and the plurality of sensing electrodes 1002 can be defined by the number of electrodes n, where n is equal to 6+4x, and where x is equal to a selection of zero or a positive integer (e.g., 6, 10, 14, 18, ...). In another non-limiting aspect, the exemplary reference MEMS structure 702 can be configured to have a number of symmetry axes given by ((n+2) / 4). In another non-limiting aspect, the exemplary reference MEMS structure 702 can be configured to have a reference arm or annular sector of a finger arm group 904 located on an axis of symmetry of the reference MEMS structure 702 in a plane above a MEMS substrate (not shown), as described above with respect to Figure 2A-2B In another non-limiting aspect of the exemplary MEMS device 700, axes of symmetry associated with the exemplary reference MEMS structure 702 (eg, axes 1402, 1404, 1406, 1408, etc.) may be separated by equal angles.

[0115] Fig.15 Further non-limiting aspects of an exemplary MEMS sensing structure 802 are depicted according to still other non-limiting embodiments. For example, the exemplary MEMS device 700 can further include an exemplary sensing MEMS structure 802, which can include a balanced sensing mass 1502 and an unbalanced sensing mass 1504. In another non-limiting aspect of the exemplary MEMS device 700, the balanced sensing mass 1502 can be symmetrical about at least the first symmetry axis 1402 in a plane above the MEMS substrate (not shown), as described above with respect to Figure 2A-2B In another non-limiting aspect of the MEMS device 700, the unbalanced sense mass 1504 can be symmetrical about at least an axis of symmetry 1404 that is orthogonal to the first axis of symmetry 1402 in a plane above the MEMS substrate (not shown), as described above with respect to Figure 2A-2B Description.

[0116] Fig.16Depicted are exemplary embodiments of tilted Z-axis out-of-plane sensing MEMS accelerometers according to various aspects described herein. What has been described above includes examples of the disclosed embodiments. Of course, it is not possible to describe every possible combination of configurations, components, and / or methods for purposes of describing the claimed subject matter, but it is understood that many further combinations and permutations of the various embodiments are possible. Accordingly, the claimed subject matter is intended to encompass all such changes, modifications, and variations that come within the spirit and scope of the appended claims. Although specific embodiments and examples are described in the subject disclosure for purposes of illustration, it is contemplated that various modifications within the scope of these described embodiments are possible.

[0117] As non-limiting examples, there are other configurations that can be designed for improved offset stability. Figure 7-15 The described exemplary embodiments allow the MEMS structure above the electrode to be symmetric about an axis orthogonal to the spring or elastic coupling axis, and the reference structure to be symmetric about at least two orthogonal axes, one of which is the spring or elastic coupling axis.

[0118] The disclosed subject matter facilitates improved deflection in exemplary MEMS structures and devices employing symmetrical MEMS structures over electrode patterns, having multiple axes of symmetry to suppress substrate deformation, wherein two axes of symmetry are the axis about which the device is tilted (in the case of a tilted MEMS device structure) and its orthogonal axis of symmetry.

[0119] The non-limiting embodiments contemplate further improvements in offset minimization of MEMS devices based on increasing the number of electrodes, but are subject to process limitations, MEMS device robustness, overall structural gain, device footprint, etc., since the compensation or reference electrodes do not contribute to the device gain. Therefore, in order to obtain a device with the same gain (e.g., the same area of ​​sensing electrodes), the device with added compensation or reference electrodes will necessarily be larger.

[0120] As used herein, the terms "inference" or "reasoning" generally refer to the process of reasoning or inferring the state of a system and / or environment from a set of observations captured through events, signals, and / or data. For example, reasoning can be used to identify a specific context or action, or can produce a probability distribution over states. Reasoning can be probabilistic, that is, a probability distribution over states of interest is computed based on a consideration of data and events. Reasoning can also refer to techniques for composing higher-level events from a set of events and / or data. Such reasoning can result in the construction of new events or actions from a set of observed events and / or stored event data, whether or not the events are related to each other in close time, and whether or not the events and data come from one or several event and data sources.

[0121] In addition, the word "example" or "exemplary" as used herein means serving as an example, instance or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as being preferred or advantageous over other aspects or designs. On the contrary, the purpose of using the word "exemplary" is to present the concept in a concrete way. In this application, the term "or" is meant to express an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified or clear from the context, "X employs A or B" refers to any natural inclusive arrangement. That is, if X employs A; X employs B; or X employs both A and B, "X employs A or B" is true in any of the above cases. In addition, the articles "a" and "an" used in this application and the appended claims should generally be interpreted as "one or more" unless otherwise specified or clearly indicated from the context as a singular form.

[0122] In addition, while an aspect may be disclosed with respect to only one of several embodiments, such features may be combined with one or more other features in other embodiments, which may be desirable and advantageous for any given or specific application. In addition, to the extent that the terms "include", "have", "comprises" and their variations and other similar words are used in the detailed description or claims, these terms are intended to be inclusive in a manner similar to the term "comprises" as an open transition word, without excluding any additional or other elements.

Claims

1. A micro-electromechanical system (MEMS) device comprising: A reference MEMS structure is located in a plane above a MEMS substrate, wherein: The reference MEMS structure is anchored to the MEMS substrate; a sensing MEMS structure substantially located in the plane above the MEMS substrate, wherein the sensing MEMS structure is configured to move in response to an external load applied to the MEMS device, wherein the reference MEMS structure is configured as a first set of arms of the reference MEMS structure and the sensing MEMS structure is configured as a second set of arms of the sensing MEMS structure, the first set of arms of the reference MEMS structure and the second set of arms of the sensing MEMS structure being arranged as sets of interdigitated arms extending radially around a center of the reference MEMS structure; an elastic coupling configured to suspend the sensing MEMS structure above the MEMS substrate; a plurality of sensing electrodes positioned parallel to the sensing MEMS structure and configured to sense a position of the sensing MEMS structure; and A plurality of reference electrodes, positioned parallel to the reference MEMS structure, are configured to sense deformation of the MEMS substrate.

2. The device according to claim 1, wherein: The reference MEMS structure is anchored to the MEMS substrate substantially at the center of the reference MEMS structure in the plane above the MEMS substrate.

3. The device according to claim 1, wherein: Each of the plurality of sensing electrodes and each of the plurality of reference electrodes are characterized by at least one of having substantially the same area or extending an equivalent radial distance from a center of an anchor, the center of the anchor being substantially located near the center of the reference MEMS structure.

4. The device according to claim 1, wherein: The elastic coupling is oriented substantially along a first symmetry axis of the reference MEMS structure, the first symmetry axis substantially intersecting the center of the reference MEMS structure in the plane above the MEMS substrate.

5. The device according to claim 4, wherein: The sensing MEMS structure includes a balanced sensing mass and an unbalanced sensing mass.

6. The device according to claim 5, wherein: The balanced sense mass is symmetric about at least the first symmetry axis in the plane above the MEMS substrate.

7. The device according to claim 5, wherein: The unbalanced sense mass is symmetric in the plane above the MEMS substrate at least about an axis of symmetry orthogonal to the first axis of symmetry.

8. The device according to claim 4, wherein: The reference MEMS structure is symmetric about a second symmetry axis in the plane above the MEMS substrate.

9. The device according to claim 8, wherein: The reference MEMS structure is symmetric about the second symmetry axis in the plane above the MEMS substrate, and the second symmetry axis is orthogonal to the first symmetry axis.

10. The device according to claim 1, wherein: The sets of interdigitated arms are configured in a circular arrangement around the center of the reference MEMS structure.

11. The device according to claim 1, wherein: The number of the first arms associated with the reference MEMS structure is different from the number of the second arms associated with the sensing MEMS structure.

12. The device according to claim 11, wherein The number of the first arm set associated with the reference MEMS structure differs from the number of the second arm set associated with the sensing MEMS structure by two interdigitated arms.

13. The apparatus according to claim 1, wherein: Each of the plurality of reference electrodes and each of the plurality of sense electrodes are associated with a respective arm within the set of interdigitated arms.

14. The apparatus according to claim 1, wherein: The number of the plurality of reference electrodes is different from the number of the plurality of sensing electrodes.

15. The apparatus according to claim 1, wherein: A total of the plurality of reference electrodes and the plurality of sensing electrodes is at least six.

16. The device according to claim 15, wherein: The sum is defined by the number of electrodes n, where n is equal to 6+4x, and where x is equal to 0 or a selection of a positive integer.

17. The apparatus according to claim 16, wherein: The reference MEMS structure has a number of symmetry axes given by ((n+2) / 4).

18. The apparatus according to claim 1, wherein: The plurality of sensing electrodes and the plurality of reference electrodes are located below the plane above the MEMS substrate.

19. The apparatus according to claim 1, wherein: The reference arm of the set of interdigitated arms associated with the reference MEMS structure is located on the axis of symmetry of the reference MEMS structure in the plane above the MEMS substrate.

20. The apparatus of claim 19, wherein: The axes of symmetry are separated by equal angles.

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