Inertial Sensors and Inertial Measurement Units

Abstract

The present invention provides an inertial sensor and an inertial measurement device, which prevent the attachment of a movable body to excessive impact. An inertial sensor (1) detects a physical quantity based on the displacement of the Z axis when three mutually orthogonal axes are set as the X axis, the Y axis and the Z axis, wherein the inertial sensor comprises: a substrate (10); a movable body (21), which is fixed to the substrate (10) and swings around a swing axis (P) along the X axis and has two mutually opposing planes (21a, 21b) and side surfaces (21c, 21d) connecting them; and a limiting portion (19), which is fixed to the substrate (10) and faces the side surfaces (21c, 21d) of the movable body (21), and the movable body (21) has an elastic portion (25) at the portion facing the limiting portion (19).

Description

Technical Field

[0001] The invention relates to an inertial sensor and an inertial measurement device. Background Art

[0002] In recent years, inertial sensors manufactured using MEMS (Micro Electro Mechanical Systems) technology have been developed. As such an inertial sensor, for example, Patent Document 1 describes a MEMS device, which includes: a base having a support portion and a fixed electrode; a movable body supported on the support portion in a manner such that the main surface and the fixed electrode are opposed to each other; and an abutment portion, which is opposed to at least a portion of the outer edge of the movable body and limits the rotational displacement of the main surface in the in-plane direction, and the MEMS device can detect acceleration in the vertical direction.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-39804

[0004] However, the MEMS device described in Patent Document 1 as an inertial sensor has the following concerns: when the movable body produces excessive rotational displacement in the in-plane direction of the main surface due to a strong external impact, etc., the movable body collides with the abutment portion. When the movable body repeatedly collides with a certain energy as a rigid body, an adhesion phenomenon called adhesion occurs between the movable body and the abutment portion. Summary of the invention

[0005] An inertial sensor detects a physical quantity based on displacement of the Z axis when three mutually orthogonal axes are set as an X axis, a Y axis, and a Z axis, the inertial sensor comprising: a substrate; a movable body fixed to the substrate, swinging around a swing axis along the X axis, and having two mutually opposing planes and a side surface connecting the two planes; and a limiting portion fixed to the substrate and opposing the side surface of the movable body, the movable body having an elastic portion at a portion opposing the limiting portion.

[0006] An inertial measurement device includes: the inertial sensor described above; and a control unit that performs control based on a detection signal output from the inertial sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a plan view schematically showing the structure of the inertial sensor according to the first embodiment.

[0008] Figure 2 yes Figure 1 Cross-section view at line AA in .

[0009] Figure 3 Yes Figure 1 The enlarged top view of part E in FIG.

[0010] Figure 4 This explains the operation of the inertial sensor. Figure 1 Cross-sectional view at line BB in .

[0011] Figure 5 It is a plan view schematically showing the structure of an inertial sensor according to a second embodiment.

[0012] Figure 6 Yes Figure 5 The enlarged top view of part F in FIG.

[0013] Figure 7 It is a plan view schematically showing the structure of an inertial sensor according to a third embodiment.

[0014] Figure 8 yes Figure 7 Cross-sectional view at line CC in .

[0015] Fig. 9 It is a cross-sectional view schematically showing the structure of an inertial sensor according to a fourth embodiment.

[0016] Fig.10 It is a cross-sectional view showing a method of manufacturing an inertial sensor.

[0017] Fig.11 It is a cross-sectional view showing a method of manufacturing an inertial sensor.

[0018] Fig.12 It is a cross-sectional view showing a method of manufacturing an inertial sensor.

[0019] Fig.13 It is a cross-sectional view showing a method of manufacturing an inertial sensor.

[0020] Fig.14 It is a cross-sectional view showing a method of manufacturing an inertial sensor.

[0021] Fig.15 It is a cross-sectional view showing a method of manufacturing an inertial sensor.

[0022] Fig.16 It is a cross-sectional view showing a method of manufacturing an inertial sensor.

[0023] Fig.17 It is a cross-sectional view showing a method of manufacturing an inertial sensor.

[0024] Fig.18 It is a plan view schematically showing the structure of an inertial sensor according to a fifth embodiment.

[0025] Fig.19 It is an exploded perspective view schematically showing the structure of an inertial measurement device including an inertial sensor according to a sixth embodiment.

[0026] Fig. 20 yes Fig.19 A three-dimensional view of the substrate.

[0027] Description of Reference Numerals

[0028] 1, 1a, 1b, 1c: inertial sensor; 10: substrate; 10a: upper surface; 11: first recess; 12: first bottom surface; 13: second recess; 14: second bottom surface; 15: support; 16: first fixed electrode; 17: second fixed electrode; 18: third fixed electrode; 19: restriction; 20: sensor element; 21: movable body; 21a, 21b: plane; 21c, 21d: side surface; 22: first movable electrode; 23: second movable Electrode; 24: third movable electrode; 25, 26: elastic portion; 27: fixed portion; 28: supporting beam portion; 29: suspension portion; 30: first connecting portion; 31: second connecting portion; 32: third connecting portion; 33: fourth connecting portion; 34: opening portion; 35: through hole; 36: protrusion; 36c: abutment surface; 41, 42, 43: connecting terminals; 50: cover body; 50a: lower surface; 51: recessed portion; G: arrow; P: swing axis; S: internal space. DETAILED DESCRIPTION

[0029] 1. First Implementation

[0030] First, regarding the inertial sensor 1 according to the first embodiment, an acceleration sensor that detects acceleration in the vertical direction is taken as an example. Figure 1 , Figure 2 , Figure 3 as well as Figure 4 Provide explanation.

[0031] It should be noted that in Figure 1 In order to facilitate the description of the internal structure of the inertial sensor 1, the state in which the cover 50 is removed is shown. Figure 1 , Figure 2 and Figure 3 The wiring provided on the substrate 10 is omitted in the figure.

[0032] In addition, for the sake of convenience of explanation, the X-axis, Y-axis and Z-axis are illustrated as three axes that are orthogonal to each other in the subsequent top view, cross-sectional view and stereoscopic view. In addition, the direction along the X-axis is referred to as the "X direction", the direction along the Y-axis is referred to as the "Y direction", and the direction along the Z-axis is referred to as the "Z direction". In addition, the front end side of the arrow in each axis direction is also referred to as the "positive side", the base end side is also referred to as the "negative side", the positive side of the Z direction is also referred to as "up", and the negative side of the Z direction is also referred to as "down". In addition, the Z direction is along the vertical direction, and the XY plane is along the horizontal plane. In addition, in this specification, the positive Z direction and the negative Z direction are collectively referred to as the Z direction.

[0033] Figure 1 as well as Figure 2 The inertial sensor 1 shown can detect the acceleration in the Z direction, which is the vertical direction, of the sensor element 20 as a physical quantity. Such an inertial sensor 1 includes: a substrate 10; a sensor element 20 disposed on the substrate 10; a restriction portion 19 disposed on the substrate 10; and a cover 50 bonded to the substrate 10 and covering the sensor element 20 and the restriction portion 19.

[0034] like Figure 1 As shown, the substrate 10 has extensions in the X direction and the Y direction, and the Z direction is set as the thickness. Figure 2 As shown, the substrate 10 is formed with a first recessed portion 11 recessed downward from the upper surface 10a of the substrate 10 and a second recessed portion 13 recessed downward from the first bottom surface 12 of the first recessed portion 11. When viewed from above in the Z direction, the first recessed portion 11 and the second recessed portion 13 enclose the sensor element 20 inside and are formed larger than the sensor element 20. The first recessed portion 11 and the second recessed portion 13 function as a retreat portion for swinging the sensor element 20. In addition, the substrate 10 has a support portion 15 protruding from the first bottom surface 12 of the first recessed portion 11 toward the sensor element 20 side, and the sensor element 20 is bonded and fixed to the support portion 15. As a result, the sensor element 20 can be fixed to the substrate 10 in a state separated from the first bottom surface 12 of the first recessed portion 11 and the second bottom surface 14 of the second recessed portion 13.

[0035] In addition, a first fixed electrode 16 and a second fixed electrode 17 are arranged on the first bottom surface 12 of the first recess 11, and a third fixed electrode 18 as a virtual electrode is arranged on the second bottom surface 14 of the second recess 13. The first fixed electrode 16 and the second fixed electrode 17 have substantially equal areas. In addition, the first fixed electrode 16 and the second fixed electrode 17 are respectively connected to a QV amplifier of an external device not shown in the figure, and the electrostatic capacitance difference thereof is detected as an electrical signal by a differential detection method. Therefore, it is preferred that the first fixed electrode 16 and the second fixed electrode 17 have equal areas.

[0036] In addition, connection terminals 41, 42, and 43 for electrically connecting an external device to the first to third fixed electrodes 16, 17, and 18 are provided on the upper surface 10a of the substrate 10 in a region where the first recess 11 and the second recess 13 are not provided. The connection terminal 41 is electrically connected to the first fixed electrode 16 via a wiring not shown, the connection terminal 42 is electrically connected to the second fixed electrode 17 via a wiring not shown, and the connection terminal 43 is electrically connected to the third fixed electrode 18 and the movable body 21 via a wiring not shown.

[0037] As the substrate 10, a substrate made of, for example, Na + The glass material containing alkali metal ions as movable ions is a glass substrate made of borosilicate glass such as Pyrex (registered trademark) glass and Tempax (registered trademark) glass. However, the substrate 10 is not particularly limited, and a silicon substrate or a quartz substrate may be used.

[0038] In addition, as the first to third fixed electrodes 16 , 17 , and 18 , metals such as Au, Pt, Ag, Cu, and Al can be used.

[0039] like Figure 2 As shown in FIG. 1 , the recessed portion 51 of the cover 50 is formed at a position overlapping with the first recessed portion 11 and the second recessed portion 13 of the substrate 10. The cover 50 accommodates the sensor element 20 in the recessed portion 51 and is bonded to the substrate 10. Furthermore, an internal space S for accommodating the sensor element 20 is formed inside the cover 50 by the cover 50 and the substrate 10.

[0040] The internal space S is an airtight space, sealed with an inert gas such as nitrogen, helium, or argon, preferably at a temperature of about -40°C to 125°C, and substantially at atmospheric pressure. However, the atmosphere of the internal space S is not particularly limited, and may be, for example, a decompressed state or a pressurized state.

[0041] As the cover 50, for example, a silicon substrate can be used. However, it is not particularly limited thereto, and for example, a glass substrate or a quartz substrate can also be used. In addition, as a method for bonding the substrate 10 and the cover 50, there is no particular limitation, and it can be appropriately selected according to the materials of the substrate 10 and the cover 50. For example, anodic bonding, activation bonding in which bonding surfaces activated by plasma irradiation are bonded to each other, bonding using bonding materials such as glass frit, metal eutectic bonding in which metal films formed on the upper surface 10a of the substrate 10 and the lower surface 50a of the cover 50 are bonded to each other, etc. can be used.

[0042] The sensor element 20 is formed by etching a conductive silicon substrate doped with impurities such as phosphorus (P), boron (B), arsenic (As), and particularly vertically processing using the Bosch process which is a deep etching technique.

[0043] like Figure 1 As shown in FIG. 1 , the sensor element 20 includes two fixed portions 27 joined and fixed to the support portion 15, two support beam portions 28 connecting the two fixed portions 27, a suspension portion 29 extending from one support beam portion 28 in the positive X direction, a suspension portion 29 extending from the other support beam portion 28 in the negative X direction, and a movable body 21 connected to the two suspension portions 29 via a first connection portion 30. The movable body 21 can be displaced in a predetermined direction relative to the fixed portion 27, and when an acceleration in the Z direction acts, the movable body 21 uses the suspension portion 29 as a swing axis P along the X axis, and torsional deforms the suspension portion 29 while swinging around the swing axis P. In other words, the movable body 21 is configured to be able to seesaw-like swing relative to the fixed portion 27 with the swing axis P as the center axis.

[0044] The movable body 21 has two planes 21a and 21b facing each other and side surfaces 21c and 21d connecting the planes 21a and 21b, and is in a rectangular shape with the long side in the Y direction when viewed from above in the Z direction. Furthermore, the movable body 21 has a first movable electrode 22 located on the positive side in the Y direction relative to the swing axis P, a second movable electrode 23 located on the negative side in the Y direction relative to the swing axis P, and a third movable electrode 24 connected to the second movable electrode 23. The first movable electrode 22, the second movable electrode 23, and the third movable electrode 24 are arranged so as to overlap with the first fixed electrode 16, the second fixed electrode 17, and the third fixed electrode 18 provided on the first bottom surface 12 of the substrate 10, respectively, when viewed from above in the Z direction.

[0045] In addition, since the second movable electrode 23 is connected to the third movable electrode 24, the movable body 21 located on the negative side of the Y direction with respect to the swing axis P is configured to be longer in the Y direction than the first movable electrode 22, which is the movable body 21 located on the positive side of the Y direction with respect to the swing axis P. Therefore, when viewed from above in the Z direction, the area of ​​the movable body 21 located on the negative side of the Y direction with respect to the swing axis P is larger than the area of ​​the movable body 21 located on the positive side of the Y direction with respect to the swing axis P, and the mass becomes larger, so the rotational moment when acceleration is applied is larger than that of the movable body 21 located on the positive side of the Y direction. When acceleration in the Z direction is applied due to the difference in rotational moment, the movable body 21 performs seesaw swinging around the swing axis P. It should be noted that the seesaw swinging means that when the first movable electrode 22 is displaced in the positive Z direction, the second movable electrode 23 is displaced in the negative Z direction, and conversely, when the first movable electrode 22 is displaced in the negative Z direction, the second movable electrode 23 is displaced in the positive Z direction.

[0046] When the inertial sensor 1 is driven, a driving signal is applied to the sensor element 20, thereby forming an electrostatic capacitance Ca between the first movable electrode 22 and the first fixed electrode 16. Similarly, an electrostatic capacitance Cb is formed between the second movable electrode 23 and the second fixed electrode 17. In a natural state where no acceleration is applied, the electrostatic capacitances Ca and Cb are substantially equal to each other.

[0047] When an acceleration in the Z direction is applied to the inertial sensor 1, the movable body 21 seesaws about the swing axis P. Due to the seesaw swing of the movable body 21, the gap between the first movable electrode 22 and the first fixed electrode 16 and the gap between the second movable electrode 23 and the second fixed electrode 17 change in opposite phases, and accordingly, the electrostatic capacitances Ca and Cb change in opposite phases to each other. Therefore, the inertial sensor 1 can detect the acceleration in the Z direction based on the difference in the capacitance values ​​of the electrostatic capacitances Ca and Cb.

[0048] In addition, the movable body 21 has an opening 34 between the first movable electrode 22 and the second movable electrode 23, and the fixing portion 27, the supporting beam portion 28, and the suspension portion 29 are arranged in the opening 34. By setting it as such a shape, the sensor element 20 can be miniaturized. In addition, a plurality of through holes 35 penetrating the two planes 21a and 21b are provided in the first to third movable electrodes 22, 23, 24 and the elastic portions 25 and 26 of the movable body 21. Therefore, the air resistance generated when the movable body 21 is displaced in the Z direction can be reduced.

[0049] The first movable electrode 22 has a second connecting portion 31 extending from the center of the end portion on the positive side in the Y direction relative to the swing axis P toward the positive Y direction. The elastic portion 25 is connected to the front end portion of the second connecting portion 31 via the third connecting portion 32 on the positive side and the negative side in the X direction of the second connecting portion 31. The elastic portion 25 is provided at a portion facing the restricting portion 19, and is configured to be rotationally displaced in the in-plane direction of the planes 21a and 21b of the movable body 21 about the third connecting portion 32 as an axis. Therefore, even if excessive rotational displacement in the in-plane direction occurs due to a strong impact from the outside, and the side surface 21c of the elastic portion 25 facing the restricting portion 19 and orthogonal to the X direction collides with the restricting portion 19, the impact caused by the collision can be reduced by the elastic function of the elastic portion 25 being deformed, and the sticking phenomenon called sticking between the movable body 21 and the restricting portion 19 can be suppressed.

[0050] In addition, if Figure 3As shown, a protrusion 36 protruding in the Y direction is provided on the side surface 21d of the elastic portion 25 that is opposite to the limiting portion 19 and is orthogonal to the Y direction. The protrusion 36 is provided on the side surface 21d at the positive X-direction end of the elastic portion 25 connected to the positive side of the second connecting portion 31 in the X direction and at the negative X-direction end of the elastic portion 25 connected to the negative side of the second connecting portion 31 in the X direction, and is configured to be rotationally displaced in the Z direction, which is a direction orthogonal to the planes 21a and 21b of the movable body 21, about the third connecting portion 32 as an axis. Therefore, when excessive acceleration in the Z direction is applied, as shown in FIG. Figure 4 As shown, even if the protrusion 36 is rotated and displaced around the swing axis P indicated by the arrow G and the abutment surface 36c of the protrusion 36 opposite to the limiting portion 19 collides with the limiting portion 19, the impact caused by the collision can be weakened by the elastic function of the deformation of the elastic portion 25, and the adhesion phenomenon between the movable body 21 and the limiting portion 19 can be suppressed.

[0051] The second movable electrode 23 has a second connecting portion 31 extending in the negative Y direction from the center of the end portion on the negative side in the Y direction relative to the swing axis P, and the elastic portion 26 is connected to the second connecting portion 31 via the third connecting portion 32 at the positive side and the negative side in the X direction of the second connecting portion 31. The third movable electrode 24 is connected to the positive X direction end of the elastic portion 26 connected to the positive side in the X direction of the second connecting portion 31 and the negative X direction end of the elastic portion 26 connected to the negative side in the X direction of the second connecting portion 31 via the fourth connecting portion 33.

[0052] The limiting portion 19 is provided to limit the rotational displacement of the planes 21a and 21b of the movable body 21 in the in-plane direction and the rotational displacement around the swing axis P. It is opposed to the side surfaces 21c and 21d of the movable body 21 and is joined and fixed to the upper surface 10a of the substrate 10.

[0053] The limiting portion 19 is formed, similarly to the sensor element 20, by simultaneously etching a conductive silicon substrate doped with impurities such as phosphorus (P), boron (B), and arsenic (As) together with the sensor element 20, in particular by vertically processing using the Bosch process, which is a deep etching technique.

[0054] In the inertial sensor 1 of the present embodiment, since the movable body 21 has the elastic portion 25 at the portion opposite to the limiting portion 19, even if an excessive rotational displacement in the in-plane direction occurs due to a strong external impact or the like and the side surface 21c of the elastic portion 25 collides with the limiting portion 19, the impact caused by the collision can be weakened by the elastic function of the deformation of the elastic portion 25, and the adhesion between the movable body 21 and the limiting portion 19 can be suppressed.

[0055] In addition, since the elastic portion 25 has a protrusion 36 protruding in the Y direction, when excessive acceleration is applied in the Z direction, even if the abutment surface 36c of the protrusion 36 opposite to the limiting portion 19 collides with the limiting portion 19, the impact caused by the collision can be weakened by the elastic function of the deformation of the elastic portion 25, and the adhesion phenomenon between the movable body 21 and the limiting portion 19 can be suppressed.

[0056] Furthermore, since the elastic portion 25 includes the through hole 35 penetrating the two flat surfaces 21 a and 21 b , the air resistance generated when the movable body 21 is displaced in the Z direction can also be reduced in the elastic portion 25 , thereby obtaining a highly sensitive inertial sensor 1 .

[0057] 2. Second Implementation

[0058] Next, refer to Figure 5 as well as Figure 6 The inertial sensor 1a according to the second embodiment will be described. Figure 5 For the sake of convenience, the diagram shows a state where the cover 50 is removed. Figure 5 In the figure, the wiring provided on the substrate 10 is omitted.

[0059] The inertial sensor 1a of this embodiment is the same as the inertial sensor 1 of the first embodiment except that the structure of the elastic portion 25a of the sensor element 20a is different from that of the inertial sensor 1 of the first embodiment. It should be noted that the description will focus on the differences from the first embodiment described above, and the description of the same matters will be omitted.

[0060] like Figure 5 and Figure 6 As shown in FIG. 1 , the inertial sensor 1a is provided with a protrusion 37 protruding in the X direction on a side surface 21c of the elastic portion 25a of the movable body 211a that is opposite to the restriction portion 19 and is orthogonal to the X direction. In addition, the protrusion 37 is provided on the side surface 21c of the elastic portion 25a connected to the positive side of the second connection portion 31 in the X direction that is opposite to the restriction portion 19, and on the side surface 21c of the elastic portion 25a connected to the negative side of the second connection portion 31 in the X direction that is opposite to the restriction portion 19.

[0061] The protrusion 37 makes the contact surface 37 c of the protrusion 37 facing the restriction portion 19 contact the restriction portion 19 , thereby improving the impact resistance due to the elastic function of the elastic portion 25 a even against an impact in the X direction.

[0062] With such a configuration, the impact resistance can be improved even against excessive impact in the X direction, and the same effects as those of the inertial sensor 1 according to the first embodiment can be obtained.

[0063] 3. Third Implementation

[0064] Next, refer to Figure 7 as well as Figure 8 The inertial sensor 1b according to the third embodiment will be described. Figure 7 For the sake of convenience, the diagram shows a state where the cover 50 is removed. Figure 7 and Figure 8 In the figure, the wiring provided on the substrate 10 is omitted.

[0065] The inertial sensor 1b of this embodiment is the same as the inertial sensor 1 of the first embodiment except that the structure of the elastic parts 25b and 26b of the sensor element 20b is different from that of the inertial sensor 1 of the first embodiment. It should be noted that the description will focus on the differences from the first embodiment described above, and the description of the same matters will be omitted.

[0066] like Figure 7 and Figure 8 As shown in FIG. 1 , the inertial sensor 1b is provided with a protrusion 38 protruding in the Z direction on the plane 21b of the elastic portion 25b of the movable body 211b facing the first fixed electrode 16. In addition, the protrusion 38 is provided at the through hole 35 closest to the restriction portion 19 and the position along the Y direction of the elastic portion 25b connected to the positive side of the second connection portion 31 in the X direction, and at the through hole 35 closest to the restriction portion 19 and the position along the Y direction of the elastic portion 25b connected to the negative side of the second connection portion 31 in the X direction. In addition, the protrusion 38 is also provided on the plane 21b of the elastic portion 26b facing the second fixed electrode 17.

[0067] An insulating film 40 is formed on the first fixed electrode 16 at a position facing the protrusion 38 of the elastic portion 25b to prevent the first fixed electrode 16 and the first movable electrode 22 from short-circuiting. In addition, an insulating film 40 is formed on the second fixed electrode 17 at a position facing the protrusion 38 of the elastic portion 26b to prevent the second fixed electrode 17 and the second movable electrode 23 from short-circuiting.

[0068] Since the contact surface 38 c of the protrusion 38 provided on the elastic parts 25 b and 26 b is in contact with the insulating film 40 , the impact resistance due to the elastic function of the elastic parts 25 b and 26 b can be improved even against an impact in the Z direction.

[0069] With such a configuration, even against excessive impact in the Z direction, the impact resistance can be further improved together with the protrusion 36 provided on the elastic portion 25 b , and the same effects as those of the inertial sensor 1 according to the first embodiment can be obtained.

[0070] 4. Fourth Implementation

[0071] Next, refer to Fig. 9 The inertial sensor 1c according to the fourth embodiment will be described. Fig. 9 is equivalent to Figure 1 This is a partial cross-sectional view taken along line AA, and illustration of wiring provided on the substrate 100 is omitted.

[0072] The inertial sensor 1c of this embodiment is the same as the inertial sensor 1 of the first embodiment except for the different structures of the substrate 100 for fixing the sensor element 20, the limiting portion 19, and the cover 50. It should be noted that the description will focus on the differences from the first embodiment described above, and the description of the same matters will be omitted.

[0073] like Fig. 9 As shown, the inertial sensor 1c has a substrate 100 that is warped concavely toward the sensor element 20. The substrate 100 is composed of a silicon substrate and has an oxide film 101 generated by thermally oxidizing the silicon substrate. The oxide film 101, which is silicon oxide (SiO2), is arranged on the surface of the substrate 100 opposite to the upper surface 100a facing the movable body 21. It should be noted that the warping of the substrate 100 is caused by the residual stress of the oxide film 101 formed only on one surface of the silicon substrate.

[0074] Due to the warping of the substrate 100, the restricting portion 19 fixed by joining to the frame portion 112 formed on the upper surface 100a of the substrate 100 is inclined toward the side surface 21d of the movable body 21, and the interval between the side surface 21d and the restricting portion 19 can be narrowed. Therefore, by warping the substrate 100, the inertial sensor 1c having a narrow interval between the movable body 21 and the restricting portion 19 can be easily manufactured.

[0075] By adopting such a configuration, it is possible to obtain an inertial sensor 1 c in which the interval between the movable body 21 and the restriction portion 19 is narrow, and it is possible to obtain the same effects as those of the inertial sensor 1 of the first embodiment.

[0076] Next, refer to Figure 10 to Figure 17 A method for manufacturing the inertial sensor 1 c according to the fourth embodiment will be described.

[0077] First, the substrate 100 composed of a silicon substrate is thermally oxidized. Fig.10 As shown, silicon oxide (SiO 2 ), namely, oxide film 101 is formed on the upper and lower surfaces of substrate 100 .

[0078] Next, if Fig.11 As shown, the oxide film 101 formed on either the upper surface or the lower surface of the substrate 100 is removed by etching or the like.

[0079] Next, the upper surface 100a from which the oxide film 101 has been removed is photolithographically processed as shown in FIG. Fig.12 As shown, the first to third fixed electrodes 16 , 17 , and 18 and wirings (not shown) are formed.

[0080] Then, if Fig.13 As shown, an oxide film 111 of silicon oxide (SiO 2 ) is formed as a sacrificial layer on the upper surface 100 a of the substrate 100 on which the first to third fixed electrodes 16 , 17 , 18 are formed by a CVD device or the like.

[0081] Next, if Fig.14 As shown, a silicon (Si) structure film 200 for forming the movable body 21 and the restricting portion 19 is formed on the oxide film 111 by a CVD device or the like. Then, the structure film 200 is doped with impurities such as phosphorus (P), boron (B), and arsenic (As) to make it conductive.

[0082] Next, the structure film 200 is processed using photolithography technology, such as Fig.15 As shown in FIG. 1 , a movable body 21 including first to third movable electrodes 22 , 23 , and 24 , a fixed portion 27 , and the like, and a restricting portion 19 are formed.

[0083] Next, if Fig.16 As shown, the oxide film 111 is etched and removed using photolithography technology except for the support portion 115 to which the fixing portion 27 is bonded and fixed, and the frame portion 112 to which the restriction portion 19 is bonded and fixed, and the frame portion 112 that includes the sensor element 20 inside.

[0084] Next, a portion of the oxide film 111 is removed from the substrate 100 on which the movable body 21 and the restricting portion 19 are formed. As a result, the residual stress of the oxide film 101 formed on the surface of the substrate 100 opposite to the upper surface 100a is reduced. Fig.17 As shown, the sensor element 20 is warped in a concave shape toward the sensor element 20 .

[0085] Then, the cover 50 is bonded to the frame 112 formed on the substrate 100 using the bonding member 60, thereby Fig. 9 As shown, it is possible to manufacture an inertial sensor 1 c in which the substrate 100 is warped concavely toward the sensor element 20 and the interval between the movable body 21 and the restricting portion 19 is narrow.

[0086] It should be noted that the manufacturing method is not limited to the above method, and a method can also be considered in which the oxide film 101 formed on either the upper or lower surface of the substrate 100 is partially removed by etching or the like, so that the film thickness of the oxide film 101 on the upper and lower surfaces is different. In addition, the film formed on the substrate 100 is not limited to the oxide film, and a method of forming a silicon nitride film (Si3N4) using a CVD device or the like can also be considered.

[0087] 5. Fifth Implementation

[0088] Next, refer to Fig.18 The inertial sensor 1d according to the fifth embodiment will be described. Fig.18 For the sake of convenience, the diagram shows a state where the cover 50 is removed. Fig.18 In the figure, the wiring provided on the substrate 10 is omitted.

[0089] The inertial sensor 1d of this embodiment is the same as the inertial sensor 1 of the first embodiment except that the structures of the first movable electrode 22d, the second movable electrode 23d and the elastic portion 25d of the sensor element 20d are different from those of the inertial sensor 1 of the first embodiment. It should be noted that the description will focus on the differences from the first embodiment described above, and the description of the same matters will be omitted.

[0090] like Fig.18 As shown in FIG. 1 , the inertial sensor 1d is provided with an elastic portion 25d extending in the positive X direction and the negative X direction on the first movable electrode 22d of the movable body 211d, and a protrusion 36d protruding in the Y direction is provided on the side surface 21d of the elastic portion 25d which is opposite to the restriction portion 19 and is orthogonal to the Y direction. It should be noted that the elastic portion 25d is connected to the front end portion of the second connecting portion 31d, and the second connecting portion 31d extends in the positive Y direction from the center of the end portion of the first movable electrode 22d on the positive side of the Y direction relative to the swing axis P. Therefore, the structure is such that the movable body 211d can be rotationally displaced in the in-plane direction of the planes 21a and 21b of the movable body 211d with the front end portion of the second connecting portion 31d as an axis, and can be rotationally displaced in the Z direction which is the orthogonal direction to the planes 21a and 21b of the movable body 211d.

[0091] In addition, the end portion of the second movable electrode 23 d in the negative Y direction is connected to the third movable electrode 24 via the fourth connecting portion 33 .

[0092] It should be noted that the elastic part 25d has a cantilever beam structure, so the resonance frequency of the elastic function part is high. Therefore, in a durability test for periodic vibrations such as a vibration test, the sensor element 20d is less likely to be damaged due to resonance, and a more reliable inertial sensor 1d can be obtained.

[0093] By adopting such a configuration, the reliability can be further improved, and the same effects as those of the inertial sensor 1 according to the first embodiment can be obtained.

[0094] 6. Sixth Implementation

[0095] Next, refer to Fig.19 as well as Fig. 20An inertial measurement device 2000 including the inertial sensors 1 to 1 d according to the sixth embodiment will be described. In the following description, the configuration of the inertial sensor 1 is used as an example.

[0096] Fig.19 The inertial measurement unit 2000 (IMU) shown is a device that detects the inertial motion amount such as the posture and behavior of a moving body such as a car or a robot. The inertial measurement unit 2000 functions as a so-called six-axis motion sensor, which includes an acceleration sensor that detects accelerations Ax, Ay, and Az along three axes and an angular velocity sensor that detects angular velocities ωx, ωy, and ωz around the three axes.

[0097] The inertial measurement device 2000 is a rectangular parallelepiped having a substantially square planar shape. In addition, screw holes 2110 as fixing portions are formed near two vertices located in the diagonal direction of the square. By passing two screws through the two screw holes 2110, the inertial measurement device 2000 can be fixed to the mounting surface of the mounting body such as a car. It should be noted that, by selecting parts and changing the design, it can also be miniaturized to a size that can be mounted on, for example, a smartphone or a digital camera.

[0098] Inertial measurement device 2000 includes housing 2100 , bonding member 2200 , and sensor module 2300 , and is configured such that sensor module 2300 is inserted into housing 2100 via bonding member 2200 . Sensor module 2300 also includes inner case 2310 and substrate 2320 .

[0099] The outer shape of housing 2100 is a rectangular parallelepiped having a substantially square planar shape similar to the overall shape of inertial measurement device 2000, and screw holes 2110 are formed near two vertices located in the diagonal direction of the square. Housing 2100 is box-shaped and contains sensor module 2300 therein.

[0100] The inner shell 2310 is a member that supports the substrate 2320 and is shaped to be accommodated inside the outer shell 2100. In addition, the inner shell 2310 is formed with a recess 2311 for preventing contact with the substrate 2320 and an opening 2312 for exposing the connector 2330 described later. Such an inner shell 2310 is joined to the outer shell 2100 via the joining member 2200. In addition, the substrate 2320 is joined to the lower surface of the inner shell 2310 by an adhesive.

[0101] like Fig. 20As shown, a connector 2330, an angular velocity sensor 2340z for detecting the angular velocity around the Z axis, an acceleration sensor unit 2350 for detecting the acceleration in the directions of the X axis, the Y axis, and the Z axis, etc. are mounted on the substrate 2320. In addition, an angular velocity sensor 2340x for detecting the angular velocity around the X axis and an angular velocity sensor 2340y for detecting the angular velocity around the Y axis are mounted on the side of the substrate 2320.

[0102] The acceleration sensor unit 2350 includes at least the above-mentioned inertial sensor 1 for measuring the acceleration in the Z direction, and can detect the acceleration in one axis direction, or detect the acceleration in two axes directions or three axes directions as needed. It should be noted that the angular velocity sensors 2340x, 2340y, and 2340z are not particularly limited, and for example, a vibration gyro sensor using the Coriolis force can be used.

[0103] In addition, a control IC 2360 is mounted on the lower surface of the substrate 2320. The control IC 2360, which is a control unit that performs control based on the detection signal output from the inertial sensor 1, is an MCU (Micro Controller Unit), which has a built-in storage unit including a non-volatile memory, an A / D converter, etc., and controls various parts of the inertial measurement device 2000. The storage unit stores a program that specifies the order and content for detecting acceleration and angular velocity, a program that digitizes the detection data and compiles it into packet data, and accompanying data. It should be noted that, in addition to this, a plurality of electronic components are also mounted on the substrate 2320.

[0104] Such an inertial measurement device 2000 uses the acceleration sensor unit 2350 including the inertial sensor 1 , and therefore it is possible to obtain an inertial measurement device 2000 that is excellent in shock resistance and has high reliability.

Claims

1. An inertial sensor, characterized in that: have: A substrate, when three mutually orthogonal axes are set as an X-axis, a Y-axis, and a Z-axis, is orthogonal to the Z-axis and is provided with a fixed electrode; a movable body, which is opposed to the fixed electrode in the Z-axis direction along the Z-axis, includes two planes orthogonal to the Z-axis and side surfaces connecting the two planes, and is arranged to be able to swing relative to the substrate around a swing axis along the X-axis; as well as a limiting portion, which is opposite to the side surface of the movable body and is fixed to the substrate, The movable body includes, at a portion opposite to the limiting portion, a pair of elastic portions; a movable electrode separated from the limiting portion by the pair of elastic portions; and a connecting portion extending from the movable electrode toward the limiting portion, the pair of elastic portions being separated from the movable electrode and connected to a front end portion of the connecting portion, and the connecting portion being arranged between the pair of elastic portions.

2. The inertial sensor according to claim 1, characterized in that: The pair of elastic portions each include a protrusion protruding in a direction along the Y-axis.

3. The inertial sensor according to claim 1, characterized in that: The pair of elastic portions each include a protrusion protruding in a direction along the X-axis.

4. The inertial sensor according to claim 1, characterized in that: The pair of elastic portions each include a protrusion protruding in a direction along the Z axis.

5. The inertial sensor according to claim 1, characterized in that: The pair of elastic parts are respectively provided with through holes penetrating the two planes.

6. The inertial sensor according to claim 1, characterized in that: The substrate includes an oxide film provided on a surface opposite to a surface facing the movable body.

7. An inertial measurement device, characterized in that: include: The inertial sensor of claim 1; as well as The control unit performs control based on the detection signal output from the inertial sensor.

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