MEMS sensor

Abstract

To improve the quality of an MEMS sensor.SOLUTION: The MEMS sensor includes: a substrate; and MEMS electrodes disposed on the substrate. The MEMS electrodes include: two sensor elements each having a fixed electrode fixed to the substrate and a movable electrode connected to the substrate so as to be movable relative to the fixed electrode in a predetermined detection direction; and a coupling unit having elasticity for mechanically connecting the movable electrodes of the two sensor elements.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to MEMS sensors. [Background technology]

[0002] Patent Document 1 discloses a capacitance-type acceleration sensor. The acceleration sensor in Patent Document 1 includes a semiconductor substrate and two Z-axis sensors formed on the semiconductor substrate. Each Z-axis sensor has a fixed electrode and a movable electrode that can vibrate relative to the fixed electrode, and acceleration in the Z-axis direction is detected by detecting a change in capacitance between the fixed electrode and the movable electrode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-088083

[0004] [overview] In the acceleration sensor of Patent Document 1, if the two movable electrodes have different resonant frequencies, the difference in the resonant frequencies of the two movable electrodes may cause the two movable electrodes to vibrate in different ways when acceleration is applied to the acceleration sensor. The difference in the behavior of the two movable electrodes when acceleration is applied to the acceleration sensor may reduce the detection accuracy and quality of the acceleration sensor.

[0005] The present disclosure aims to improve the quality of MEMS sensors.

[0006] One aspect of the present disclosure is A substrate; a MEMS electrode disposed on the substrate; Equipped with The MEMS electrode is two sensor elements each having a fixed electrode fixed to the substrate and a movable electrode connected to the substrate so as to be movable in a predetermined detection direction relative to the fixed electrode; a connecting portion having elasticity that mechanically connects the movable electrodes of the two sensor elements together; The present invention provides a MEMS sensor comprising: [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a plan view of an acceleration sensor according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a plan view of an acceleration sensor according to a modified example of the embodiment of the present disclosure. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 5 is a plan view of an acceleration sensor according to a further modified example of an embodiment of the present disclosure.

[0008] [Detailed explanation] A MEMS (Micro Electro Mechanical System) sensor according to an embodiment of the present disclosure will be described below with reference to the accompanying drawings. Note that the following description is essentially merely exemplary and is not intended to limit the present disclosure, its applications, or its uses. The drawings are schematic, and the dimensional ratios and the like differ from those of the actual devices.

[0009] [First embodiment] FIG. 1 is a plan view schematically illustrating a MEMS sensor 1 according to a first embodiment of the present disclosure. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. The MEMS sensor 1 according to this embodiment is a capacitance-type acceleration sensor manufactured using semiconductor microfabrication technology.

[0010] In the following description, for convenience, among the directions along each side of the MEMS sensor 1 in the plan view shown in FIG. 1, the left-right direction in FIG. 1 will be referred to as the X direction, the up-down direction in FIG. 1 will be referred to as the Y direction, and the thickness direction of the MEMS sensor 1 in the cross-sectional view shown in FIG. 2 (the up-down direction in FIG. 2) will be referred to as the Z direction. In particular, in FIG. 1, the right side may be referred to as the +X direction, the left side as the -X direction, the upper side as the +Y direction, and the lower side as the -Y direction. In FIG. 2, the upper side may be referred to as the +Z direction and the lower side as the -Z direction. In this embodiment, the X direction, the Y direction, and the Z direction are perpendicular to one another.

[0011] The MEMS sensor 1 of this embodiment is a Z-axis sensor that detects acceleration in the Z direction applied to the MEMS sensor 1. That is, the Z direction of this embodiment is an example of a detection direction according to the present disclosure. Referring to Figures 1 and 2, the MEMS sensor 1 has a substrate 10 and a MEMS electrode 20 provided in the substrate 10.

[0012] The substrate 10 has a rectangular shape in a planar view. The thickness direction of the substrate 10 coincides with the Z direction. The substrate 10 has a first main surface 10a located on the +Z side and a second main surface 10b located on the -Z side and facing the first main surface 10a. The substrate 10 is a conductive silicon (Si) substrate. The first main surface 10a and the second main surface 10b are planar and extend in the X and Y directions. The first main surface 10a and the second main surface 10b extend parallel to each other. An insulating layer 11 is disposed on the first main surface 10a of the substrate 10. The substrate 10 has a cavity 12 that is rectangular in a planar view and recessed from the first main surface 10a toward the -Z side. The substrate 10 has a bottom wall 13 that is rectangular in a planar view and defines the -Z side of the cavity 12. Although the surface located on the +Z side of the bottom wall 13 is shown as flat in FIG. 2, in the actual MEMS sensor 1 it is not flat.

[0013] The MEMS electrode 20 has two sensor elements 30A and 30B. In the following description, when there is no need to particularly distinguish between the two sensor elements 30A and 30B, one of the two sensor elements 30A and 30B may be simply referred to as the sensor element 30.

[0014] The sensor element 30 includes a pair of anchors 31 and 32 fixed to the bottom wall 13 of the substrate 10, and a fixed electrode 40 and a movable electrode 50 supported by the pair of anchors 31 and 32. The fixed electrode 40 and the movable electrode 50 are made of conductive silicon. In this embodiment, the movable electrode 50 is disposed so as to surround the fixed electrode 40. Note that although the pair of anchors 31 and 32 are disposed at a predetermined distance in the Y direction in FIG. 1, they may be disposed closer together than shown in FIG. 1. For example, the pair of anchors 31 and 32 may be disposed so close together that the distance between them in the Y direction is less than 40 μm. In this case, the pair of anchors 31 and 32 can be mechanically regarded as a single anchor.

[0015] The fixed electrode 40 is spaced from the bottom wall 13 of the substrate 10 on the +Z side. The fixed electrode 40 includes a comb-shaped fixed electrode portion 41 and a fixed frame 42 that supports the fixed electrode portion 41. In the following description, the fixed electrode 40, fixed electrode portion 41, and fixed frame 42 included in the sensor element 30A may be referred to as the fixed electrode 40A, fixed electrode portion 41A, and fixed frame 42A, respectively. Furthermore, the fixed electrode 40, fixed electrode portion 41, and fixed frame 42 included in the sensor element 30B may be referred to as the fixed electrode 40B, fixed electrode portion 41B, and fixed frame 42B, respectively.

[0016] The fixed electrode portion 41 has a comb-like shape. Specifically, the fixed electrode portion 41 has a plurality of electrode fingers that extend in the X direction and are spaced apart from one another in the Y direction. The fixed electrode portion 41 is mechanically connected to the substrate 10 by a fixed frame 42 so that it cannot move relative to the substrate 10.

[0017] The fixed frame 42 includes first to fifth fixed beams 43 to 47. One end of the fixed frame 42 is supported by the anchor 31, and the other end of the fixed frame 42 is supported by the anchor 32. In other words, the fixed frame 42 is supported at both ends by the pair of anchors 31, 32.

[0018] The first fixed beam 43 extends linearly in the Y direction. The first fixed beam 43 is disposed on the +Y side of the anchor 31. The -Y side end of the first fixed beam 43 is mechanically connected to the anchor 31 via the isolation joint 33. The first fixed beam 43 and the anchor 31 are electrically insulated and mechanically connected by the isolation joint 33.

[0019] The second fixing beam 44 extends linearly in the Y direction. The second fixing beam 44 is disposed on the -Y side of the anchor 32. The +Y side end of the second fixing beam 44 is mechanically connected to the anchor 32 via the isolation joint 34. The second fixing beam 44 and the anchor 32 are electrically insulated and mechanically connected by the isolation joint 34.

[0020] The third fixed beam 45 extends linearly in the X direction. In the fixed frame 42A, the third fixed beam 45 is disposed on the -X side relative to the first fixed beam 43. In the fixed frame 42B, the third fixed beam 45 is disposed on the +X side relative to the first fixed beam 43. The third fixed beam 45 is mechanically connected to the +Y side end of the first fixed beam 43.

[0021] The fourth fixed beam 46 extends linearly in the X direction. In the fixed frame 42A, the fourth fixed beam 46 is disposed on the +X side relative to the second fixed beam 44. In the fixed frame 42B, the fourth fixed beam 46 is disposed on the -X side relative to the second fixed beam 44. The fourth fixed beam 46 is mechanically connected to the -Y side end of the second fixed beam 44.

[0022] An oxide film 42a is laminated on the +Z side of the third and fourth fixing beams 45, 46 of fixing frame 42A. In this embodiment, oxide film 42a is made of silicon oxide (SiO2) formed by thermally oxidizing substrate 10. Oxide film 42a has a thermal expansion coefficient smaller than that of fixing frame 42. The third and fourth fixing beams 45, 46 of fixing frame 42A are deformed due to the difference between the thermal stress generated in the third and fourth fixing beams 45, 46 and the thermal stress generated in oxide film 42a, and extend while curving toward the -Z side as they approach the -X side.

[0023] Fifth fixed beam 47 extends linearly in the Y direction. In fixed frame 42A, fifth fixed beam 47 connects the -X side ends of third fixed beam 45 and fourth fixed beam 46 to each other. In fixed frame 42B, fifth fixed beam 47 connects the +X side ends of third fixed beam 45 and fourth fixed beam 46 to each other. Furthermore, in fixed frame 42A, fifth fixed beam 47 is arranged on the +X side of the multiple electrode fingers of fixed electrode unit 41 and is mechanically connected to the +X side ends of the multiple electrode fingers. In fixed frame 42B, fifth fixed beam 47 is arranged on the -X side of the multiple electrode fingers of fixed electrode unit 41 and is mechanically connected to the -X side ends of the multiple electrode fingers.

[0024] The movable electrode 50 is spaced from the bottom wall 13 of the substrate 10 on the +Z side. The movable electrode 50 includes a comb-shaped movable electrode portion 51 and a movable frame 52 that supports the movable electrode portion 51. In the following description, the movable electrode 50, movable electrode portion 51, and movable frame 52 included in the sensor element 30A may be referred to as the movable electrode 50A, movable electrode portion 51A, and movable frame 52A, respectively. Furthermore, the movable electrode 50, movable electrode portion 51, and movable frame 52 included in the sensor element 30B may be referred to as the movable electrode 50B, movable electrode portion 51B, and movable frame 52B, respectively.

[0025] The movable electrode portion 51 has a comb-like shape. Specifically, the movable electrode portion 51 extends in the X direction and has a plurality of electrode fingers spaced apart from one another in the Y direction. The movable electrode portion 51 is mechanically connected to the substrate 10 by a movable frame 52 so as to be movable in the Z direction relative to the substrate 10. The movable electrode portion 51 is arranged to mesh with the fixed electrode portion 41. Specifically, the plurality of electrode fingers of the movable electrode portion 51 and the plurality of electrode fingers of the fixed electrode portion 41 are arranged alternately in the Y direction.

[0026] The movable frame 52 includes first to fifth movable beams 53 to 57 and two movable springs 58, 59. One end of the movable frame 52 is supported by the anchor 31, and the other end of the movable frame 52 is supported by the anchor 32. In other words, the movable frame 52 is supported at both ends by the pair of anchors 31, 32.

[0027] The first movable beam 53 extends linearly in the Y direction. The first movable beam 53 is disposed on the +Y side of the anchor 31. The -Y side end of the first movable beam 53 is mechanically connected to the anchor 31 via the isolation joint 35. The first movable beam 53 and the anchor 31 are electrically insulated and mechanically connected by the isolation joint 35.

[0028] The second movable beam 54 extends linearly in the Y direction. The second movable beam 54 is disposed on the -Y side of the anchor 32. The +Y side end of the second movable beam 54 is mechanically connected to the anchor 32 via the isolation joint 36. The second movable beam 54B and the anchor 32 are electrically insulated and mechanically connected by the isolation joint 36.

[0029] The third movable beam 55 extends linearly in the X direction. In the movable frame 52A, the third movable beam 55 is disposed on the -X side relative to the first movable beam 53. In the movable frame 52B, the third movable beam 55 is disposed on the +X side relative to the first movable beam 53. The third movable beam 55 is mechanically connected to the +Y side end of the first movable beam 53 via a movable spring 58.

[0030] The fourth movable beam 56 extends linearly in the X direction. In the movable frame 52A, the fourth movable beam 56 is disposed on the -X side relative to the second movable beam 54. In the movable frame 52B, the fourth movable beam 56 is disposed on the +X side relative to the second movable beam 54. The fourth movable beam 56 is mechanically connected to the -Y side end of the second movable beam 54 via a movable spring 59.

[0031] An oxide film 52a is laminated on the +Z side of the third and fourth movable beams 55, 56 of the movable frame 52B. In this embodiment, the oxide film 52a is made of silicon oxide (SiO2) formed by thermally oxidizing the substrate 10. The oxide film 52a has a thermal expansion coefficient smaller than that of the movable frame 52. The third and fourth movable beams 55, 56 of the movable frame 52B are deformed due to the difference between the thermal stress generated in the third and fourth movable beams 55, 56 and the thermal stress generated in the oxide film 52a, and extend while curving toward the -Z side as they approach the +X side.

[0032] The fifth movable beam 57 extends linearly in the Y direction. In the movable frame 52A, the fifth movable beam 57 connects the -X side ends of the third movable beam 55 and the fourth movable beam 56 to each other. In the movable frame 52B, the fifth movable beam 57 connects the +X side ends of the third movable beam 55 and the fourth movable beam 56 to each other. Furthermore, in the movable frame 52A, the fifth movable beam 57 is disposed on the -X side of the multiple electrode fingers of the movable electrode unit 51 and is mechanically connected to the -X side ends of the multiple electrode fingers. In the movable frame 52B, the fifth movable beam 57 is disposed on the +X side of the multiple electrode fingers of the movable electrode unit 51 and is mechanically connected to the +X side ends of the multiple electrode fingers.

[0033] The movable springs 58 and 59 extend in the Y direction. The movable spring 58 connects the first movable beam 53 and the third movable beam 55 to each other. The movable spring 59 connects the second movable beam 54 and the fourth movable beam 56 to each other. The movable springs 58 and 59 have a rectangular cross section in the extension direction, i.e., in a cross section perpendicular to the Y direction. The movable spring 58 has a width narrower than the width of the first movable beam 53, i.e., the dimension in the X direction. Similarly, the movable spring 59 has a width narrower than the width of the second movable beam 54.

[0034] The movable springs 58, 59 can elastically torsionally deform around a central axis extending along the Y direction. As a result, the movable spring 58 allows the third movable beam 55 to rotate around the central axis extending along the Y direction. Similarly, the movable spring 59 allows the fourth movable beam 56 to rotate around the central axis extending along the Y direction. In other words, the movable springs 58, 59 of this embodiment function as torsion bars.

[0035] The movable springs 58, 59 of this embodiment can be elastically bent and deformed in the Z direction along the Y direction. That is, the movable springs 58, 59 can be elastically deflected in the Z direction along the Y direction. This allows the movable spring 58 to move the third movable beam 55 in the Z direction. Similarly, the movable spring 59 allows the fourth movable beam 56 to move in the Z direction.

[0036] The movable springs 58 and 59 are elastically twisted and bent, thereby allowing the movable electrode portion 51 to move relatively to the fixed electrode portion 41 in the Z direction.

[0037] The MEMS electrode 20 includes an elastic connecting portion 60 that connects the movable electrodes 50A, 50B of the two sensor elements 30A, 30B. Specifically, the connecting portion 60 in this embodiment connects the fifth movable beams 57 of the movable electrodes 50A, 50B. The connecting portion 60 is made of conductive silicon.

[0038] The connecting portion 60 is elastically deformable so as to absorb the difference in relative position between the movable electrodes 50A and 50B in the detection direction (the Z direction in this embodiment). Specifically, the connecting portion 60 has two connecting springs 61 and 62 that are elastically deformable in the Z direction. The two connecting springs 61 and 62 have a rectangular cross section in a cross section perpendicular to the extension direction. The connecting springs 61 and 62 are elastically bendable and deformable in the Z direction along the extension direction. The two connecting springs 61 and 62 elastically bend and deform in the Z direction along the extension direction, allowing the connecting portion 60 as a whole to expand and contract in the Z direction. The expansion and contraction of the connecting portion 60 as a whole in the Z direction makes it possible to absorb the difference in relative position between the movable electrodes 50A and 50B in the detection direction.

[0039] The connecting springs 61, 62 are formed with lower rigidity than the movable springs 58, 59, and are easily deformed in the Z direction. This makes it difficult for stress to be transmitted between the movable electrodes 50A, 50B. In this embodiment, the bending rigidity of the two connecting springs 61, 62 is lower than the bending rigidity of the movable springs 58, 59. In this embodiment, the thickness of the two connecting springs 61, 62, i.e., the dimension in the Z direction, is thinner than the thickness of the movable springs 58, 59.

[0040] The sensor element 30 includes fixed electrode wiring 37 electrically connected to the fixed electrode 40. The fixed electrode wiring 37 is laminated on the +Z side of the insulating layer 11. The fixed electrode wiring 37 has a fixed electrode contact 37a that penetrates the insulating layer 11 in the Z direction and is electrically connected to the fixed electrode 40, a fixed electrode joint 37b located on the anchor 31, and a wiring portion 37c that extends from the fixed electrode contact 37a across the isolation joint 33 in the Y direction to the fixed electrode joint 37b. Here, the portion of the insulating layer 11 that is laminated on the +Z side of the fixed electrode 40 is located only in the vicinity of the fixed electrode contact 37a.

[0041] The sensor element 30A of this embodiment includes a movable electrode wiring 38 electrically connected to the movable electrode 50. The movable electrode wiring 38 is laminated on the +Z side of the insulating layer 11. The movable electrode wiring 38 has a movable electrode contact 38a that penetrates the insulating layer 11 in the Z direction and is electrically connected to the movable electrode 50, a movable electrode joint 38b located on the anchor 32, and a wiring portion 38c that extends from the movable electrode contact 38a across the isolation joint 36 in the Y direction to the movable electrode joint 38b.

[0042] A first input voltage, which is an AC voltage, is applied to the fixed electrode 40A via fixed electrode wiring 37 electrically connected to the fixed electrode 40A. A second input voltage, which is in opposite phase to the first input voltage, is applied to the fixed electrode 40B via fixed electrode wiring 37 electrically connected to the fixed electrode 40B. In addition, the movable electrodes 50A and 50B are electrically connected to each other by a connecting portion 60. As a result, the movable electrodes 50A and 50B and the connecting portion 60 are at the same potential.

[0043] In this embodiment, in the sensor element 30A, the fixed electrode portion 41 of the fixed electrode 40A and the movable electrode portion 51 of the movable electrode 50A form a first capacitor C1. Similarly, in the sensor element 30B, the fixed electrode portion 41 of the fixed electrode 40B and the movable electrode portion 51 of the movable electrode 50B form a second capacitor C2. The MEMS sensor 1 detects a change in voltage accompanying a change in the capacitance of the first and second capacitors C1 and C2 via the movable electrode wiring 38, thereby detecting acceleration in the Z direction.

[0044] In this embodiment, in sensor element 30A, the third and fourth fixed beams 45, 46 of fixed frame 42A extend while curving toward the -Z side toward the -X side, so that the fixed electrode portion 41 of fixed electrode 40A is disposed on the -Z side relative to the movable electrode portion 51 of movable electrode 50A. On the other hand, in sensor element 30B, the third and fourth movable beams 55, 56 of movable frame 52B extend while curving toward the -Z side toward the +X side, so that the movable electrode portion 51 of movable electrode 50B is disposed on the -Z side relative to the fixed electrode portion 41 of fixed electrode 40B.

[0045] When acceleration on the +Z side is applied to the MEMS sensor 1, in both sensor elements 30A and 30B, the movable electrode portion 51 is displaced toward the -Z side due to inertial force. At this time, in sensor element 30A, the opposing area between the fixed electrode portion 41 and the movable electrode portion 51 increases, so the capacitance of the first capacitor C1 increases. On the other hand, in sensor element 30B, the opposing area between the fixed electrode portion 41 and the movable electrode portion 51 decreases, so the capacitance of the second capacitor C2 decreases. Furthermore, when acceleration on the -Z side is applied to the MEMS sensor 1, in both sensor elements 30A and 30B, the movable electrode portion 51 is displaced toward the +Z side due to inertial force. At this time, in sensor element 30A, the opposing area between the fixed electrode portion 41 and the movable electrode portion 51 decreases, so the capacitance of the first capacitor C1 decreases. On the other hand, in the sensor element 30B, the capacitance of the second capacitor C2 increases because the opposing area between the fixed electrode portion 41 and the movable electrode portion 51 increases. In the MEMS sensor 1 of this embodiment, the direction of acceleration applied to the MEMS sensor can be detected by detecting an increase or decrease in the capacitance of the first and second capacitors C1 and C2.

[0046] The MEMS sensor 1 according to this embodiment has the following advantages.

[0047] (1) MEMS sensor 1 is a substrate 10; MEMS electrodes 20 disposed on a substrate 10; Equipped with The MEMS electrode 20 is two sensor elements 30A and 30B each having a fixed electrode 40 fixed to a substrate 10 and a movable electrode 50 connected to the substrate 10 so as to be movable in a predetermined detection direction relative to the fixed electrode 40; a connecting portion having elasticity for mechanically connecting the movable electrodes 50A and 50B of the two sensor elements 30A and 30B to each other; Equipped with.

[0048] According to this configuration, the movable electrodes 50A, 50B of the two sensor elements 30A, 30B are mechanically connected to each other by the elastic connecting portion 60, so that the movable electrodes 50 of the two sensor elements 30A, 30B have a common resonance frequency. This allows the movable electrodes 50A, 50B to vibrate in the same manner when acceleration is applied to the MEMS sensor 1. As a result, it is possible to suppress a decrease in the detection accuracy of the MEMS sensor 1, and to improve the quality of the MEMS sensor 1.

[0049] (2) The connecting portion 60 is elastically deformable so as to absorb the difference in relative position between the movable electrode 50 of one sensor element 30 and the movable electrode 50 of the other sensor element 30 in the detection direction.

[0050] This configuration can reduce the influence that the movement of the movable electrode 50 of one sensor element 30 has on the movement of the other sensor element 30. As a result, the quality of the MEMS sensor 1 can be improved.

[0051] (3) The movable electrode 50 has elastically deformable movable springs 58 and 59 that can be elastically bent and deformed in the detection direction, The connecting portion 60 has connecting springs 61 and 62 that can be elastically bent and deformed in the detection direction. The bending stiffness of the connecting springs 61 and 62 is smaller than the bending stiffness of the movable springs 58 and 59 .

[0052] In this configuration, the bending rigidity of the connecting springs 61, 62 is smaller than the bending rigidity of the movable springs 58, 59, and therefore the connecting springs 61, 62 can bend and deform more easily than the movable springs 58, 59. As a result, when acceleration is applied to the movable electrode 50 of one sensor element 30, the movement of the movable electrode 50 of one sensor element 30 is absorbed by the elastic deformation of the connecting springs 61, 62, and elastic deformation of the movable springs 58, 59 of the movable electrode 50 of the other sensor element 30 can be suppressed. As a result, the effect of the movement of the movable electrode 50 of one sensor element 30 on the movement of the other sensor element 30 can be reduced, and the quality of the MEMS sensor 1 can be improved.

[0053] (4) The connecting portion 60 and the movable electrodes 50A and 50B of the two sensor elements 30A and 30B are at the same potential.

[0054] According to this configuration, the connecting portion 60 and the movable electrodes 50A, 50B of the two sensor elements 30A, 30B are at the same potential, so there is no need to electrically insulate the movable electrodes 50A, 50B of the two sensor elements 30A, 30B. There is no need to arrange an element such as an isolation joint for electrically insulating the movable electrodes 50 of the two sensor elements 30A, 30B in the connecting portion 60 that mechanically connects the movable electrodes 50 of the two sensor elements 30A, 30B, and the structure of the MEMS sensor 1 can be simplified.

[0055] (5) The detection direction is the thickness direction of the substrate 10. In one sensor element 30B, when no acceleration is applied, the movable electrode 50 is bent to one side in the thickness direction relative to the fixed electrode 40, In the other sensor element 30A, the fixed electrode 40 is bent to one side in the thickness direction relative to the movable electrode 50 when no acceleration is applied.

[0056] In this configuration, the movable electrode 50 of the sensor element 30B is bent toward one side in the thickness direction (the −Z side in this embodiment) relative to the fixed electrode 40, while in the sensor element 30A, the fixed electrode 40 is bent toward one side in the thickness direction relative to the movable electrode 50. In this configuration, when the movable electrode 50 moves to one side in the thickness direction, the capacitance of the second capacitor C2 formed by the movable electrode 50 and fixed electrode 40 of one sensor element 30B decreases, and the capacitance of the first capacitor C1 formed by the movable electrode 50 and fixed electrode 40 of the other sensor element 30A increases. Furthermore, when the movable electrode 50 moves to the other side in the thickness direction, the capacitance of the second capacitor C2 formed by the movable electrode 50 and fixed electrode 40 of one sensor element 30B increases, and the capacitance of the first capacitor C1 formed by the movable electrode 50 and fixed electrode 40 of the other sensor element 30B decreases. As a result, by detecting an increase or decrease in the capacitance of the first and second capacitors C1 and C2, it is possible to detect the direction of acceleration applied to the MEMS sensor 1. In this way, even if the movable electrode 50 of one sensor element 30B and the movable electrode 50 of the other sensor element 30A have different shapes, the movable electrodes 50 of the two sensor elements 30A and 30B are mechanically connected to each other by the connecting portion 60, so that the movable electrodes 50A and 50B of the two sensor elements 30A and 30B have a common resonant frequency, thereby suppressing a decrease in the detection accuracy of the MEMS sensor 1. As a result, the quality of the MEMS sensor 1 can be improved.

[0057] [Variations] The present disclosure is not limited to the configurations described in the above embodiments, and various modifications are possible.

[0058] Fig. 3 is a plan view of a MEMS sensor 101 according to a modification of the embodiment. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 3. In this modification, components corresponding to those in the MEMS sensor 1 according to the embodiment are denoted by the same reference numerals in the 100s, and detailed descriptions thereof will be omitted.

[0059] 3 and 4, the MEMS sensor 101 of this modification differs from the embodiment in that the fixed electrode 140 is disposed so as to surround the movable electrode 150, in that the movable electrode 50 is disposed so as to surround the fixed electrode 40. Furthermore, the MEMS electrode 120 of this modification divides the connecting portion 160 into a first portion 160a connected to the movable electrode 150A of the sensor element 130A and a second portion 160b connected to the movable electrode 150B of the sensor element 130B, and includes an isolation joint 139 that mechanically connects the first portion 160a and the second portion 160b while electrically insulating them. In this modification, the sensor element 30B also has a movable electrode wiring 138. In this modification, a connecting spring 161 is disposed in the first portion 160a, and a connecting spring 162 is disposed in the second portion 160b. In addition, in this modified example, a first detection voltage, which is an AC voltage, is applied to the movable electrode 150A via the movable electrode wiring 138, and a second detection voltage, which is an AC voltage of opposite phase to the first detection voltage, is applied to the movable electrode 150B via the movable electrode wiring 138.

[0060] 3 and 4, the first portion 160a of the connecting portion 160 connected to the movable electrode 150A of the sensor element 130A and the second portion 160b connected to the movable electrode 50B of the other sensor element 30B are electrically insulated by the isolation joint 139. That is, the two movable electrodes 150A and 150B are electrically insulated by the isolation joint 139. This configuration allows different voltages to be applied to the two movable electrodes 150A and 150B. As a result, the degree of freedom in designing the MEMS sensor 1 can be improved.

[0061] 5 is a plan view of a MEMS sensor 201 according to another modification of the embodiment. In this modification, components corresponding to those in the MEMS sensor 201 according to the embodiment are assigned the same reference numerals in the 200s, and detailed descriptions thereof will be omitted.

[0062] 5, MEMS sensor 201 of this modified example differs from the embodiment in which movable electrode 50 is arranged to surround fixed electrode 40 in that fixed electrode 240 is arranged to surround movable electrode 250. MEMS sensor 201 of this modified example also differs from the modified examples shown in FIGS. 3 and 4 only in that movable electrodes 250A, 250B and connecting portion 260 are at the same potential and no isolation joint 139 is provided.

[0063] For example, in the above embodiment, the connecting portion 60 has the connecting springs 61 and 62 that are expandable and contractible in the Z direction, but the connecting portion according to the present disclosure is not limited to this. The connecting portion according to the present disclosure may not have the connecting springs, and may have another element that mechanically connects the two movable electrodes together and functions to absorb differences in the relative positions of the two movable electrodes in the detection direction.

[0064] In the above embodiment, a Z-axis acceleration sensor has been described as an example of a MEMS sensor according to the present disclosure, but the MEMS sensor according to the present disclosure may also be an X-axis acceleration sensor or a Y-axis acceleration sensor, or may be another sensor such as a gyro sensor.

[0065] [Note] The MEMS sensor according to the present disclosure provides the following aspects.

[0066] [Aspect 1] A substrate; a MEMS electrode disposed on the substrate; Equipped with The MEMS electrode is two sensor elements each having a fixed electrode fixed to the substrate and a movable electrode connected to the substrate so as to be movable in a predetermined detection direction relative to the fixed electrode; a connecting portion having elasticity that mechanically connects the movable electrodes of the two sensor elements together; A MEMS sensor comprising:

[0067] [Aspect 2] 2. The MEMS sensor of claim 1, wherein the connecting portion is elastically deformable to absorb a difference in relative position in the detection direction between the movable electrode of one sensor element and the movable electrode of the other sensor element.

[0068] [Aspect 3] the movable electrode has an elastically deformable movable spring that can be elastically bent and deformed in the detection direction, the connecting portion has a connecting spring that is elastically bendable and deformable in the detection direction, 3. The MEMS sensor of claim 1 or 2, wherein the connecting spring has a bending stiffness less than the bending stiffness of the movable spring.

[0069] [Aspect 4] 4. The MEMS sensor according to any one of aspects 1 to 3, wherein the connecting portion and the movable electrodes of the two sensor elements are at the same potential.

[0070] [Aspect 5] 5. The MEMS sensor of any one of aspects 1 to 4, further comprising an isolation joint that divides the connecting portion into a first portion connected to the movable electrode of one sensor element and a second portion connected to the movable electrode of the other sensor element, and that mechanically connects the first portion and the second portion while electrically insulating them.

[0071] [Aspect 6] the detection direction is a thickness direction of the substrate, In one of the sensor elements, when no acceleration is applied, the movable electrode is bent toward one side in the thickness direction relative to the fixed electrode, Aspect 6. The MEMS sensor according to any one of aspects 1 to 5, wherein in the other sensor element, when no acceleration is applied, the fixed electrode is bent toward one side in the thickness direction relative to the movable electrode. [Explanation of symbols]

[0072] 1 MEMS sensor 10 Substrate 10a First principal surface 10b Second principal surface 11 Insulating layer 12 cavities 13 Bottom wall 20 MEMS electrodes 30 sensor element 31 Anchor 32 Anchor 33 Isolation joint 34 Isolation joint 35 Isolation joint 36 Isolation joint 37 Fixed electrode wiring 37a Fixed electrode contact 37b Fixed electrode junction 37c Wiring section 38 Movable electrode wiring 38a Movable electrode contact 38b Movable electrode joint 38c wiring section 40 Fixed electrode 41 Fixed electrode section 42 Fixed Frame 43 First fixed beam 44 Second fixed beam 45 Third Fixed Beam 46 4th fixed beam 47 5th Fixed Beam 50 Movable electrode 51 Movable electrode part 52 Movable Frame 53 First Movable Beam 54 Second movable beam 55 Third Movable Beam 56 4th Movable Beam 57 5th Movable Beam 58 Movable spring 59 Movable spring 60 Connection part 61 Connecting spring 62 Connecting spring

Claims

1. A substrate; a MEMS electrode disposed on the substrate; Equipped with The MEMS electrode is two sensor elements each having a fixed electrode fixed to the substrate and a movable electrode connected to the substrate so as to be movable in a predetermined detection direction relative to the fixed electrode; a connecting portion having elasticity that mechanically connects the movable electrodes of the two sensor elements together; A MEMS sensor comprising:

2. The MEMS sensor according to claim 1 , wherein the connecting portion is elastically deformable so as to absorb a difference in relative position in the detection direction between the movable electrode of one sensor element and the movable electrode of the other sensor element.

3. the movable electrode has an elastically deformable movable spring that can be elastically bent and deformed in the detection direction, the connecting portion has a connecting spring that is elastically bendable and deformable in the detection direction, The MEMS sensor of claim 1 , wherein the connecting spring has a bending stiffness less than the bending stiffness of the movable spring.

4. The MEMS sensor according to claim 1 , wherein the connecting portion and the movable electrodes of the two sensor elements are at the same potential.

5. 2. The MEMS sensor according to claim 1, further comprising an isolation joint that divides the connecting portion into a first portion connected to the movable electrode of one sensor element and a second portion connected to the movable electrode of the other sensor element, and that mechanically connects the first portion and the second portion while electrically insulating them.

6. the detection direction is a thickness direction of the substrate, In one of the sensor elements, when no acceleration is applied, the movable electrode is bent toward one side in the thickness direction relative to the fixed electrode, 2. The MEMS sensor according to claim 1, wherein in the other sensor element, when no acceleration is applied, the fixed electrode is bent to one side in the thickness direction relative to the movable electrode.

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