Physical quantity sensor and inertial measurement device

Abstract

To provide a physical quantity sensor which has high robustness to strong impact.SOLUTION: A physical quantity sensor includes: a support substrate 2 having a protrusion 24a; a fixed body 4 which is fixed to the support substrate 2 and which has a first fixed electrode 412 as a first electrode; a fixed part 52 fixed to the support substrate 2; a spring 53 connected to the fixed part 52; and a first movable electrode 561 as a second electrode, which is connected to the spring 53 and which faces the first fixed electrode 412. A movable body 5 includes a plurality of slits s1, s2, s3, s4 which are superimposed on the protrusion 24a in planar view.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a physical quantity sensor and an inertial measurement unit including the physical quantity sensor. [Background technology]

[0002] 2. Description of the Related Art As a physical quantity sensor using MEMS (Micro Electro Mechanical Systems) technology, for example, the one described in Patent Document 1 is known. Patent Document 1 describes a physical quantity sensor having a movable part that is displaceable in the X-axis direction relative to a substrate, and a convex part provided on the substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-100723 A Summary of the Invention [Problem to be solved by the invention]

[0004] For such physical quantity sensors, further improvement is desired in terms of robustness against strong shocks. [Means for solving the problem]

[0005] A physical quantity sensor according to one embodiment of the present application comprises a supporting substrate having a convex portion, a fixed body fixed to the supporting substrate and having a first electrode, a fixed portion fixed to the supporting substrate, a spring connected to the fixed portion, and a second electrode connected to the spring and facing the first electrode, and a movable body displaceable along a first direction parallel to a main surface of the supporting substrate, wherein the movable body includes a plurality of slits that overlap with the convex portion in a planar view.

[0006] An inertial measurement unit according to one aspect of the present application includes the above-described physical quantity sensor. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a plan view of a physical quantity sensor according to a first embodiment. [Diagram 2] Cross-sectional view of the physical quantity sensor taken along line II-II in Figure 1. [Diagram 3] FIG. 3 is a cross-sectional view of the physical quantity sensor taken along line III-III in FIG. [Figure 4A] FIG. [Figure 4B] FIG. [Diagram 5] FIG. 2 is an enlarged plan view of region V in FIG. 1 . [Figure 6] FIG. 13 is a plan view of a modified example of the protrusion. [Figure 7] FIG. 11 is a plan view of a physical quantity sensor according to a second embodiment. [Figure 8] FIG. 8 is a cross-sectional view of the physical quantity sensor taken along line VIII-VIII in FIG. 7 . [Figure 9] FIG. 8 is a cross-sectional view of the physical quantity sensor taken along line IX-IX in FIG. 7 . [Figure 10A] FIG. 13 is a plan view of a modified example of the protrusion. [Figure 10B] 13 is a cross-sectional view of a modified example of the protrusion. FIG. [Figure 11] FIG. 1 is an exploded perspective view showing a schematic configuration of an inertial measurement unit. [Figure 12] FIG. 2 is a perspective view of a substrate on which a physical quantity sensor is mounted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the dimensions of the components may be shown on different scales in order to make the components easier to see. For ease of explanation, the three mutually orthogonal axes are referred to as the X-axis, Y-axis, and Z-axis, and the direction parallel to the X-axis is also referred to as the "X-axis direction," the direction parallel to the Y-axis is also referred to as the "Y-axis direction," and the direction parallel to the Z-axis is also referred to as the "Z-axis direction." The tip side of the arrow direction of each axis is also referred to as the "plus side," and the opposite side is also referred to as the "negative side." In addition, hereinafter, viewing in the Z-axis direction is also referred to as the "planar view," and viewing from the X-axis or Y-axis direction of a cross section including the Z-axis is also referred to as the "cross-sectional view."

[0009] Furthermore, in the following description, for example, the term "on the substrate" refers to a substrate that is disposed in contact with the substrate, that is disposed on the substrate via another structure, or that is disposed partially in contact with the substrate and partially disposed via another structure. The term "upper surface" refers to the surface of the substrate on the positive side in the Z-axis direction, for example, "upper surface of the lid" refers to the surface of the lid on the positive side in the Z-axis direction. The term "lower surface" refers to the surface of the lid on the negative side in the Z-axis direction.

[0010] 1. Embodiment 1 A physical quantity sensor 1 according to a first embodiment will be described with reference to FIGS. FIG. 1 is a plan view of the physical quantity sensor 1. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. FIG. 4A is an enlarged plan view of the slit portion 33a, and FIG. 4B is an enlarged cross-sectional view of the slit portion 33a. FIG. 5 is an enlarged plan view of an area V in FIG. 1. FIG. 6 is an enlarged plan view of a protrusion 24a according to a modified example. For ease of explanation, the cover 8 is made transparent in FIG. 1.

[0011] 1 is an acceleration sensor used to detect acceleration Ax in the X-axis direction. Such physical quantity sensor 1 has a support substrate 2, a cover 8, and an element substrate 3 that is disposed between the support substrate 2 and the cover 8 and has a sensor element 31, which is the acceleration sensor main body, provided thereon.

[0012] The physical quantity sensor 1 may include a detection circuit and an output circuit. The detection circuit performs detection processing on the signal output from the sensor element 31, and the output circuit outputs the signal obtained by the detection processing as a detection signal.

[0013] The physical quantity sensor 1 of the first embodiment will be described in detail below in the following sections: 1.1. Support Substrate 1.2. Lid 1.3. Element substrate 1. Movable body 2. Fixed body 3. Slit section 1. Length a < Length b 2. Length G1 < Length G2 1.4. Variations

[0014] 1.1. Support Substrate As shown in FIG. 1, the support substrate 2 has a rectangular shape in a plan view. 2 or 3, the support substrate 2 has a cavity 21 formed as a recess on the upper surface side. The planar shape of the cavity 21 is larger than the sensor element 31 so as to enclose the sensor element 31 inside, as shown in Fig. 1. This cavity 21 functions as a relief portion for preventing contact between the sensor element 31 and the support substrate 2.

[0015] In this embodiment, the support substrate 2 is a glass substrate. As the glass substrate, a glass substrate made of a glass material containing alkali metal ions, which are mobile ions, for example, borosilicate glass such as Pyrex (registered trademark) glass, can be used. Since the glass substrate is optically transparent, the state of the sensor element 31 can be visually confirmed from the outside of the physical quantity sensor 1.

[0016] The support substrate 2 is not limited to a glass substrate. For example, a silicon substrate or a ceramic substrate may be used as the support substrate 2. When using a silicon substrate, it is preferable to use a high-resistance silicon substrate or a silicon substrate on which a silicon oxide film, which is an insulating oxide, is formed on the surface by thermal oxidation or the like, from the viewpoint of preventing short circuits. A high-resistance silicon substrate is a silicon substrate having a resistivity of approximately 10 Ωcm or more. The conductive carrier concentration of such a silicon substrate is 1×10 15 cm -3 This is preferable from the viewpoint of preventing short circuits since the thickness is as follows: Furthermore, if a thermal oxide film of about 0.5 to 3 μm is formed on the surface, the insulation property is improved and the parasitic capacitance of the sensor element 31 is reduced, which is even more preferable.

[0017] As shown in FIG. 2 or 3, the support substrate 2 has a mount portion 22 made up of large and small protrusions provided on the bottom surface of a cavity 21, and protrusions 24a, 24b, 24c, and 24d. A sensor element 31 is joined to the mount portion 22 .

[0018] The protrusions 24a, 24b, 24c, and 24d are stoppers for suppressing large displacement of the sensor element 31 in the Z-axis direction. Note that a large displacement in the Z-axis direction is a displacement in which the sensor element 31 would collide with the bottom surface of the cavity 21 if the protrusions 24a, 24b, 24c, and 24d were not present. In addition, when a direction parallel to the main surface 32 of the element substrate 3 is defined as an in-plane direction, the Z-axis direction can be rephrased as an out-of-plane direction.

[0019] The protrusions 24a, 24b, 24c, and 24d are shorter than the mount portion 22 and are provided so as to have a predetermined distance between them and the sensor element 31 when stationary. When the sensor element 31 is displaced in the Z-axis direction due to unexpected vibration or impact including an external force in the out-of-plane direction or an inertial force, the convex portions 24a, 24b, 24c, and 24d are the first to come into contact with the movable body 5 of the sensor element 31, thereby suppressing further displacement. Therefore, by suppressing large displacement of the movable body 5 of the sensor element 31, the occurrence of defects such as cracks and fractures in the movable body 5 of the sensor element 31 is suppressed.

[0020] 1, grooves 23a, 23b, and 23c are provided on the upper surface of the support substrate 2. One end of the grooves 23a, 23b, and 23c is provided on the outside of the lid 8, and the other end is provided on the upper surface of the mount portion 22 with the cavity 21 in between.

[0021] Wires 71, 72, and 73 are provided in the grooves 23a, 23b, and 23c. One ends of the wires 71, 72, and 73 are connected to external connection terminals 75, 76, and 77 provided on the outside of the lid 8, respectively.

[0022] The other ends of the wirings 71, 72, and 73 are routed through the cavity 21 to the grooves 23a, 23b, and 23c on the upper surface of the mount portion 22. The wirings 71, 72, and 73 are electrically connected to the sensor element 31 at contact portions c1, c2, and c3, respectively.

[0023] The material of the wirings 71, 72, and 73 is not particularly limited. For example, metal materials such as gold (Au), silver (Ag), platinum (Pt), palladium (Pd), iridium (Ir), copper (Cu), aluminum (Al), nickel (Ni), titanium (Ti), and tungsten (W), alloys containing these metal materials, and oxide-based transparent conductive materials such as ITO (indium tin oxide), IZO (indium zinc oxide), ZnO (zinc oxide), and IGZO can be used. In addition, one or more of these materials can be combined to form a laminate of, for example, two or more layers.

[0024] 1.2. Lid As shown in FIG. 1, the cover 8 has a rectangular shape in a plan view. 2 or 3, the lid 8 has a cavity 81 consisting of a recess on the underside. The lid 8 is bonded to the periphery of the support substrate 2 using a bonding material 35 described below. The cavity 81 of the lid 8 and the cavity 21 of the support substrate 2 form a storage space S. The sensor element 31 is stored in the storage space S.

[0025] As shown in FIG. 2, the cover 8 has a communication hole 82 that communicates between the inside and outside of the storage space S, and this communication hole 82 can be used to create a desired atmosphere in the storage space S.

[0026] The storage space S is preferably filled with an inert gas such as nitrogen, helium, or argon, and is at approximately atmospheric pressure at the operating temperature (approximately -40°C to 80°C). By keeping the storage space S at atmospheric pressure, viscous resistance increases, a damping effect is exhibited, and the vibration of the movable body 5 of the sensor element 31 can be quickly converged or stopped.

[0027] A sealing member 83 is disposed in the communication hole 82. The sealing member 83 is not particularly limited as long as it can seal the communication hole 82, and examples of the sealing member 83 that can be used include various alloys such as gold (Au) / tin (Sn) alloys, gold (Au) / germanium (Ge) alloys, and gold (Au) / aluminum (Al) alloys, and glass materials such as low-melting glass. Instead of using the sealing member 83, the material of the lid 8 may be directly melted by laser light or the like.

[0028] In this embodiment, the lid 8 is made of a silicon substrate. However, the lid 8 is not limited to a silicon substrate. For example, a glass substrate or a ceramic substrate may be used for the lid 8.

[0029] The method of bonding the lid body 8 and the support substrate 2 is not particularly limited. The method of bonding the lid body 8 and the support substrate 2 may be appropriately selected from, for example, anodic bonding, activation bonding in which bonding surfaces activated by plasma irradiation are bonded together, bonding using a bonding material such as glass frit, diffusion bonding or eutectic bonding in which metal films formed on the bonding surfaces are bonded together, etc. In this embodiment, the lid body 8 and the support substrate 2 are bonded by heat treatment at 300° C. or more using a bonding material 35 made of glass frit. This allows the storage space S to be sealed well.

[0030] In addition, when a bonding material such as glass frit is not used to bond the lid body 8 and the element substrate 3, in order to prevent the inside and outside of the storage space S from becoming connected through the grooves 23a, 23b, and 23c, it is advisable to adopt a method of sealing the grooves 23a, 23b, and 23c with a SiO2 film formed by a CVD method using TEOS (tetraethoxysilane), for example.

[0031] 1.3. Element substrate As shown in FIG. 1, the element substrate 3 includes a sensor element 31 provided inside the cavity 21 in a plan view.

[0032] The sensor element 31 has a fixed body 4 and a movable body 5. The fixed body 4 is provided so that its position does not change in the sensor element 31. The movable body 5 is provided so that its position relative to the fixed body 4 can be changed along the X-axis direction, which is the detection axis direction.

[0033] The element substrate 3 is a silicon substrate doped with impurities such as phosphorus (P) and boron (B). The resistivity of the element substrate 3 is preferably 0.01 to 0.02 Ωcm. In this case, when the doped impurity is boron (B), the conductive carriers are 3 to 5×10 18 cm ―3 This makes it easier to transmit the applied potential, and therefore it is possible to efficiently extract an electrical signal from the sensor element 31. The sensor element 31 is formed by patterning the element substrate 3 made of a silicon substrate.

[0034] A part of the sensor element 31 formed from the element substrate 3 is bonded to the mount portion 22 of the support substrate 2. Note that the method of bonding the element substrate 3 to the support substrate 2 and the method of bonding the sensor element 31 to the mount portion 22 are not particularly limited. Note that the sensor element 31 is bonded to the support substrate 2 in an electrically insulated state.

[0035] In this embodiment, the thickness of the element substrate 3 is 20 μm or more and 50 μm or less. This allows the element substrate 3 to be thinned while adequately maintaining the mechanical strength of the sensor element 31. This allows the physical quantity sensor 1 to be made smaller and thinner.

[0036] 1.3.1. Movable objects The movable body 5 has a suspension bar 51, a fixed portion 52, springs 53 and 54, and a movable portion 55. The suspension bar 51, the fixed portion 52, the springs 53 and 54, and the movable portion 55 are integrally formed and electrically connected to each other.

[0037] 2, the lower surface side of the fixed portion 52 is joined to the mount portion 22. The fixed portion 52 is electrically connected to the wiring 71 via the contact portion c1. As shown in FIG. 1, the suspension bar 51 connects between a fixed part 52 and a spring 53 . The spring 53 connects the positive side of the movable part 55 in the X-axis direction and the suspension bar 51 . The spring 54 connects the negative side of the X-axis direction of the movable part 55 and the fixed part 52 .

[0038] The movable portion 55 is provided by the springs 53 and 54 so as to be displaceable along the X-axis direction, which is the direction of the detection axis, in the in-plane direction of the main surface 32 of the element substrate 3. In other words, the movable portion 55 is provided so as to be displaceable in the X-axis direction, which is parallel to the main surface 32 of the element substrate 3, to the positive side in the X-axis direction and the negative side in the X-axis direction. In this way, since movable part 55 is supported on both sides in the X-axis direction by springs 53 and 54, the posture and behavior of movable part 55 are stable, and acceleration can be detected with higher accuracy.

[0039] In this embodiment, the X-axis direction is an example of a first direction, and the Y-axis direction is an example of a second direction. The physical quantity sensor 1 is an inertial sensor having a detection axis in an in-plane direction of the main surface 32 of the element substrate 3. When the physical quantity sensor 1 is an acceleration sensor used to detect acceleration Ay in the Y-axis direction, the Y-axis direction corresponds to the first direction, and the X-axis direction corresponds to the second direction.

[0040] The width of the suspension bar 51, in other words, the length in the Y-axis direction, is smaller than the width of the fixed part 52, in other words, the length in the Y-axis direction. This allows the suspension bar 51 to be made smaller, and the mass of the movable part 55 to be increased without increasing the size of the movable body 5. Therefore, the physical quantity can be detected with higher accuracy while preventing the sensor element 31 from becoming larger. In the following description, a virtual axis that bisects the suspension bar 51 in the Y-axis direction in a plan view is defined as a central axis L. As shown in Fig. 1, the movable body 5 is provided with a shape that is line-symmetrical with respect to the central axis L.

[0041] The movable portion 55 has a frame-like shape in a plan view, and is provided so as to surround the suspension bar 51, the fixed portion 52, the springs 53, 54, and the fixed body 4. In this way, by forming the movable part 55 in a frame shape, it is possible to increase the mass of the movable part 55 while reducing the size of the movable part 55. Therefore, it is possible to detect the physical quantity with higher accuracy while preventing the sensor element 31 from becoming large.

[0042] The movable portion 55 has a frame portion 551, a first Y-axis extending portion 552, a first X-axis extending portion 553, a second Y-axis extending portion 554, a second X-axis extending portion 555, a first protruding portion 556, a second protruding portion 557, and a movable electrode 56. In this embodiment, the movable electrode 56 is an example of a second electrode.

[0043] The movable electrode 56 has a first movable electrode 561 and a second movable electrode 562 . The first movable electrode 561 is made up of a first movable electrode 561a and a first movable electrode 561b, and the second movable electrode 562 is made up of a second movable electrode 562a and a second movable electrode 562b.

[0044] The frame portion 551 is a portion of the four sides of the outer periphery of the movable portion 55. The first Y-axis extending portion 552 is a portion extending from a side of the central axis L of the frame portion 551 on the positive side in the Y-axis direction to the negative side in the Y-axis direction. A slit portion 33a is provided at a portion where the first Y-axis extending portion 552 and the frame portion 551 intersect. The slit portion 33a is provided at a position overlapping with the protrusion 24a in a plan view. The details of the slit portion 33a will be described later. The first X-axis extending portion 553 is a portion that extends from the tip end of the first Y-axis extending portion 552 towards the negative side in the X-axis direction.

[0045] The first protrusion 556 is a portion that protrudes from the side on the positive side of the Y axis direction of the central axis L of the frame portion 551 toward the negative side in the Y axis direction. A slit portion 33d is provided at a portion where the first protrusion 556 and the frame portion 551 intersect. The slit portion 33d is provided at a position that overlaps with the convex portion 24d in a plan view. The details of the slit portion 33d will be described later. The side of frame portion 551 on the positive side in the Y-axis direction of center axis L, first Y-axis extension portion 552 , first X-axis extension portion 553 , and first protrusion portion 556 are provided to surround first opening portion 558 .

[0046] The second Y-axis extending portion 554 is a portion extending from a side on the negative side of the Y-axis direction of the central axis L of the frame portion 551 to the positive side of the Y-axis direction. A slit portion 33b is provided at a portion where the second Y-axis extending portion 554 and the frame portion 551 intersect. The slit portion 33b is provided at a position overlapping with the protrusion 24b in a plan view. The details of the slit portion 33b will be described later. The second X-axis extending portion 555 is a portion that extends from the tip end of the second Y-axis extending portion 554 towards the negative side in the X-axis direction.

[0047] The second protruding portion 557 is a portion protruding from a side on the negative side of the central axis L of the frame portion 551 in the Y-axis direction toward the positive side of the Y-axis direction. A slit portion 33c is provided at a portion where the second protruding portion 557 and the frame portion 551 intersect. The slit portion 33c is provided at a position overlapping with the convex portion 24c in a plan view. The details of the slit portion 33c will be described later. The side of frame portion 551 on the negative Y-axis direction side of central axis L, second Y-axis extension portion 554 , second X-axis extension portion 555 , and second protrusion portion 557 are provided to surround second opening portion 559 .

[0048] A plurality of first movable electrodes 561a are provided on the side on the positive side in the Y axis direction of the central axis L of the frame portion 551. Each of the plurality of first movable electrodes 561a is provided such that the longitudinal direction extends to the negative side in the Y axis direction from the side on the positive side in the Y axis direction of the frame portion 551. The length of the plurality of first movable electrodes 561a in the Y axis direction gradually decreases toward the positive side in the X axis direction.

[0049] A plurality of first movable electrodes 561b are provided on the first X-axis extending portion 553. Each of the plurality of first movable electrodes 561b is provided such that the longitudinal direction extends from the first X-axis extending portion 553 to the Y-axis direction positive side. The length of the plurality of first movable electrodes 561b in the Y-axis direction gradually increases toward the X-axis direction positive side.

[0050] A plurality of second movable electrodes 562b are provided on the second X-axis extending portion 555. Each of the plurality of second movable electrodes 562b is provided such that the longitudinal direction extends from the second X-axis extending portion 555 to the negative Y-axis direction. The length of the plurality of second movable electrodes 562b in the Y-axis direction gradually increases toward the positive X-axis direction.

[0051] A plurality of second movable electrodes 562a are provided on a side on the negative Y-axis direction of the central axis L of the frame portion 551. Each of the plurality of second movable electrodes 562a is provided such that the longitudinal direction extends from the side on the negative Y-axis direction of the frame portion 551 to the positive Y-axis direction. The length of the plurality of second movable electrodes 562a in the Y-axis direction gradually decreases toward the positive X-axis direction. As described above, in this embodiment, the slit portions 33a, 33b, 33c, and 33d are arranged at four locations in the movable portion 55. More specifically, the slit portions 33a, 33b, 33c, and 33d are arranged so as to surround the first opening 558 and the second opening 559. In the first opening 558 and the second opening 559, a plurality of first movable electrodes 561a, a plurality of first movable electrodes 561b, a plurality of second movable electrodes 562a, and a plurality of second movable electrodes 562b are arranged.

[0052] 1.3.2. Fixed body The fixed body 4 has a first fixed body 41 and a second fixed body 42. The first fixed body 41 is located within the first opening 558 , and the second fixed body 42 is located within the second opening 559 .

[0053] The first fixed body 41 has a fixed portion 413 joined to the mounting portion 22, a first stator bar 411 supported by the fixed portion 413, and a first fixed electrode 412 extending from the first stator bar 411 on both sides in the Y-axis direction.

[0054] The fixed portion 413, the first stator bar 411, and the first fixed electrode 412 are integrally formed and electrically connected to each other. The fixed portion 413 is electrically connected to the wiring 72 via the contact portion c2.

[0055] The first stator bar 411 has a long and thin rod shape, and is provided between the plurality of first movable electrodes 561a and the plurality of first movable electrodes 561b. First stator bar 411 extends in a direction inclined with respect to each of the X-axis and Y-axis in a plan view. Specifically, first stator bar 411 is inclined so that the distance from central axis L increases toward the tip side of first stator bar 411. By arranging in this manner, fixing portion 413 can be easily arranged close to fixing portion 52.

[0056] The inclination of the first stator bar 411 with respect to the X-axis is not particularly limited, but is preferably 10° to 45°, and more preferably 10° to 30°. This makes it possible to suppress the spread of the first fixed body 41 in the Y-axis direction, and to reduce the size of the sensor element 31.

[0057] The first fixed electrode 412 includes a plurality of first fixed electrodes 412a and a plurality of first fixed electrodes 412b. In this embodiment, the first fixed electrode 412 is an example of a first electrode.

[0058] Each of the multiple first fixed electrodes 412a is provided such that the longitudinal direction extends from the first stator bar 411 toward the positive side in the Y-axis direction. The first fixed electrode 412a is provided so as to face the first movable electrode 561a on the positive side in the X-axis direction with a length G1 therebetween, which is a gap length between the electrodes, which will be described later.

[0059] Each of the multiple first fixed electrodes 412b is provided such that its longitudinal direction extends from the first stator bar 411 toward the negative side in the Y-axis direction. The first fixed electrode 412b is provided so as to face the first movable electrode 561b on the positive side in the X-axis direction with a distance G1 therebetween, which will be described later.

[0060] The length of each of the multiple first fixed electrodes 412a, that is, the length in the Y-axis direction, gradually decreases toward the positive side in the X-axis direction. The length of each of the multiple first fixed electrodes 412b, that is, the length in the Y-axis direction, gradually increases toward the positive side in the X-axis direction.

[0061] The second fixed body 42 has a fixed portion 423 joined to the mounting portion 22, a second stator bar 421 supported by the fixed portion 423, and a second fixed electrode 422 extending from the second stator bar 421 on both sides in the Y-axis direction.

[0062] The fixed portion 423, the second stator bar 421, and each of the second fixed electrodes 422 are integrally formed and electrically connected to each other. The fixed portion 423 is electrically connected to the wiring 73 via the contact portion c3.

[0063] The second stator bar 421 has a long, rod-like shape, and is provided between the plurality of second movable electrodes 562a and the plurality of second movable electrodes 562b. The second stator bar 421 extends in a direction inclined with respect to both the X-axis and the Y-axis in a plan view.

[0064] The second fixed electrode 422 includes a plurality of second fixed electrodes 422a and a plurality of second fixed electrodes 422b. In this embodiment, the second fixed electrode 422 is an example of a first electrode. Each of the multiple second fixed electrodes 422a is provided so that the longitudinal direction extends toward the negative Y-axis direction from the second stator bar 421. The multiple second fixed electrodes 422a are provided so as to face the second movable electrode 562a on the negative X-axis direction side with a length G1 (described later) between them.

[0065] Each of the multiple second fixed electrodes 422b is provided such that the longitudinal direction extends toward the positive side in the Y axis direction from the second stator bar 421. The multiple second fixed electrodes 422b are provided such that they face the second movable electrode 562b on the negative side in the X axis direction with a length G1 (described later) between them.

[0066] The length of the multiple second fixed electrodes 422a, that is, the length in the Y-axis direction, gradually decreases toward the positive side in the X-axis direction. The length of the multiple second fixed electrodes 422b, that is, the length in the Y-axis direction, gradually increases toward the positive side in the X-axis direction.

[0067] When acceleration in the positive X-axis direction is applied to such sensor element 31, the movable portion 55 is displaced in the negative X-axis direction while elastically deforming the springs 53 and 54 based on the magnitude of the acceleration.

[0068] As a result of this displacement, the length G1 between the first movable electrode 561a and the first fixed electrode 412a, between the first movable electrode 561b and the first fixed electrode 412b, between the second movable electrode 562a and the second fixed electrode 422a, and between the second movable electrode 562b and the second fixed electrode 422b changes.

[0069] This change in length G1 changes the magnitude of each of the electrostatic capacitances between first movable electrode 561a and first fixed electrode 412a, between first movable electrode 561b and first fixed electrode 412b, between second movable electrode 562a and second fixed electrode 422a, and between second movable electrode 562b and second fixed electrode 422b.

[0070] The physical quantity sensor 1 of this embodiment is provided so as to be able to detect these changes in capacitance. The detection circuit and the output circuit output detection signals based on these changes in capacitance. Thus, the acceleration Ax in the X-axis direction can be detected.

[0071] 1.3.3. Slit section 4A and 4B, the slit portion 33a is a general term for a configuration including a plurality of slits s1, s2, s3, and s4, an inter-slit extending portion b1 between the slits s1 and s2, an inter-slit extending portion b2 between the slits s2 and s3, and an inter-slit extending portion b3 between the slits s3 and s4. Since the slit portions 33b, 33c, and 33d are configured similarly to the slit portion 33a, the configuration of the slit portion 33a will be described as a representative thereof.

[0072] As shown in Fig. 4A, each of the slits s1, s2, s3, and s4 is a slit whose longitudinal direction extends in the X-axis direction. Also, as shown in Fig. 4B, each of the slits s1, s2, s3, and s4 is a through hole that penetrates between the upper and lower surfaces of the element substrate 3 in the Z-axis direction.

[0073] The portion with the slits 33a has higher flexibility than the other portion, in other words, the portion where the slits 33a are not provided. Therefore, when the sensor element 31 is displaced in the Z-axis direction due to unexpected vibration or impact including an external force in an out-of-plane direction or an inertial force, the convex portion 24a collides with the highly flexible slit portion 33a in the movable portion 55, and the impact is absorbed by the slit portion 33a, thereby preventing the occurrence of cracks or breaks in the movable portion 55. In other words, the robustness against strong impacts can be improved. In addition, when the contact between the sensor element 31 and the protruding portion 24a is repeated many times due to long-term vibration, a sliding portion is formed between the sensor element 31 and the protruding portion 24a. In general, sticking between the two substances can occur when the contact and sliding between the two substances is repeated. This occurs when the surface energy of the sliding portion increases and the adhesive force becomes greater than the restoring force. In general, the adhesive force is affected by the surface energy, surface roughness, area, etc. of the two surfaces that are adhesive. The portion with the slit portion 33a can reduce the contact area or sliding area with the protruding portion 24a compared to when the slit portion 33a is not provided. In other words, in-use sticking of the sensor element 31 can be reduced.

[0074] The longitudinal direction of the slits s1, s2, s3, and s4 may be the Y-axis direction. However, it is more preferable that the longitudinal direction of the slits s1, s2, s3, and s4 is the same as the detection axis direction of the physical quantity sensor 1. Therefore, when the physical quantity sensor 1 is an acceleration sensor used to detect acceleration Ax in the X-axis direction, it is preferable that the longitudinal direction of the slits s1, s2, s3, and s4 be in the X-axis direction rather than in the Y-axis direction. Similarly, when the physical quantity sensor 1 is an acceleration sensor used to detect acceleration Ay in the Y-axis direction, it is preferable that the longitudinal direction of the slits s1, s2, s3, and s4 be in the Y-axis direction rather than in the X-axis direction. The reason for this will be explained in the next section.

[0075] 1.3.3.1. Length a < Length b In this embodiment, the relationship between length a and length b is length a<length b. The effects of this will be described below. The length a is the width of each of the inter-slit extending portions b1, b2, and b3, i.e., the length of each of the inter-slit extending portions b1, b2, and b3 along the Y-axis direction. In other words, the length a is the length between adjacent slits s1 and s2, between adjacent slits s2 and s3, and between adjacent slits s3 and s4. The length b is the length of the protrusion 24a along the Y-axis direction.

[0076] In this embodiment, the length a is configured to be smaller than the length b. Furthermore, the total length 3a (length a×3) of the inter-slit extending portions b1, b2, and b3 is configured to be smaller than the length b. The relationship of length a<length a×3<length b is realized by arranging the longitudinal directions of the slits s1, s2, s3, and s4 in the X-axis direction, which is the same as the detection axis direction of the physical quantity sensor 1.

[0077] The protrusion 24a is provided at a position overlapping with the inter-slit extending portions b1, b2, and b3. The length a can be rephrased as the length between adjacent slits s1 and s2, between slits s2 and s3, or between slits s3 and s4.

[0078] When the sensor element 31 is displaced in the Z-axis direction due to unexpected vibration or impact including an external force in the out-of-plane direction or an inertial force and comes into contact with the convex portion 24a, the only part of the sensor element 31 that comes into contact with the convex portion 24a is the portion of length a of the inter-slit extension portions b1, b2, and b3. This reduces the area of ​​contact between the sensor element 31 and the protruding portion 24a, thereby preventing the sensor element 31 from sticking to the protruding portion 24a.

[0079] Similarly, even if the sensor element 31 and the convex portion 24a are displaced in the X-axis direction while remaining in contact with each other and slide against each other, the only part of the sensor element 31 that slides against the convex portion 24a is the part of length a of the inter-slit extension portions b1, b2, and b3. This reduces the area of ​​the sliding portion where the sensor element 31 and the protruding portion 24a come into contact with each other, thereby preventing the sensor element 31 from sticking to the protruding portion 24a.

[0080] Next, we will compare the case where the longitudinal direction of slits s1, s2, s3, and s4 is aligned in the X-axis direction, which is the same as the detection axis direction, with the case where it is aligned in the Y-axis direction, which is an in-plane direction perpendicular to the detection axis direction, to explain why aligning the longitudinal direction of slits s1, s2, s3, and s4 in the same direction as the detection axis direction can better suppress in-use sticking of the sensor element 31.

[0081] The movable part 55 is provided in a structure that is flexible in the X-axis direction, which is the detection axis direction, but is difficult to bend in other axial directions. Therefore, the restoring force in the detection axis direction is weaker than the restoring force when it is bent in an axial direction other than the detection axis.

[0082] As described above, the sensor element 31 sticks to the protrusion 24a when the sensor element 31 repeatedly comes into contact with or slides against the protrusion 24a, and the surface energy of the contact or sliding portion between the sensor element 31 and the protrusion 24a increases, causing the adhesive force to exceed the restoring force. In general, the adhesive force is affected by the surface energy, surface roughness, area, etc. of the two surfaces that are being adhesively attached.

[0083] When the sensor element 31 is tilted in the Z-axis direction due to unexpected vibration or impact including an external force or inertial force in the out-of-plane direction, if the longitudinal direction of the slits s1, s2, s3, and s4 is the X-axis direction, the contact or sliding portion between the sensor element 31 and the protrusion 24a is only the portion of length a of each of the inter-slit extensions b1, b2, and b3. On the other hand, if the longitudinal direction of the slits s1, s2, s3, and s4 is the Y-axis direction, the contact or sliding portion between the sensor element 31 and the protrusion 24a is the portion of length b where the inter-slit extensions b1, b2, and b3 extending in the Y-axis direction overlap with the protrusion 24a.

[0084] Therefore, as described above, since length a<length a×3<length b, the longitudinal direction of the slits s1, s2, s3, and s4 is aligned in the X-axis direction, which is the same as the detection axis direction, in order to reduce the area of ​​the contact or sliding portion between the sensor element 31 and the convex portion 24a. Therefore, the adhesive force can be reduced, and even with a weak restoring force, the adhesion can be released.

[0085] 1.3.3.2. Length G1 < Length G2 In this embodiment, the relationship between length G1 and length G2 is length G1<length G2. The effects of this will be described below. As shown in FIG. 5, the length G1 is the gap length between the second fixed electrode 422b and the adjacent second movable electrode 562b on the negative side in the X-axis direction. As shown in FIG. 4A, the length G2 is the length between the end of the convex portion 24a and the ends of the slits s1, s2, s3, and s4 in the X-axis direction which is the detection axis direction.

[0086] In this embodiment, the length between the ends of the slits s1, s2, s3, and s4 on both sides of the protrusion 24a is set to the length G2, but only one side may be set to the length G2. In this case, it is preferable to set the side farther from the center of gravity of the sensor element 31 to the length G2.

[0087] The maximum displacement range of the sensor element 31 in the X-axis direction is a length G1 which is the gap length between the electrodes. Therefore, as shown in FIG. 5, even if the sensor element 31 is displaced in the X-axis direction, the convex portion 24b does not protrude from the slit portion 33b in a plan view. Therefore, the sensor element 31 can be prevented from sticking to the protrusion 24b.

[0088] 1.4. Variations The above-described embodiment may be modified in various ways. Specific modifications will be described below as examples. 6, the planar shape of the protrusion 24a may be elliptical, or may be circular or polygonal having three or more sides.

[0089] As described above, the physical quantity sensor 1 of this embodiment includes the support substrate 2 having the convex portion 24a, the fixed body 4 fixed to the support substrate 2 and having the first fixed electrode 412 as a first electrode, the fixed portion 52 fixed to the support substrate 2, the spring 53 connected to the fixed portion 52, and the first movable electrode 561 connected to the spring 53 and serving as a second electrode facing the first fixed electrode 412, and the movable body 5 includes a plurality of slits s1, s2, s3, s4 that overlap with the convex portion 24a in a planar view.

[0090] In this way, since the movable body 5 includes the multiple slits s1, s2, s3, and s4 that overlap with the convex portion 24a in a plan view, robustness against strong impact can be improved, and a highly reliable physical quantity sensor 1 having excellent impact resistance can be realized.

[0091] In addition, in the physical quantity sensor 1 of this embodiment, in the Y-axis direction, which is a second direction intersecting the X-axis direction, the length a between adjacent slits s1 and s2 among the multiple slits s1, s2, s3, and s4 is smaller than the length b of the convex portion 24a. Therefore, the contact / sliding area between the sensor element 31 and the protruding portion 24a can be reduced, which makes it possible to prevent the sensor element 31 from sticking during use. In other words, a highly reliable physical quantity sensor 1 without failure can be realized.

[0092] In addition, in the physical quantity sensor 1 of this embodiment, the length G2 between the end of the convex portion 24a and the ends of the slits s1, s2, s3, and s4 in the X-axis direction is greater than the length G1 between the first fixed electrode 412 and the first movable electrode 561. Therefore, even if the sensor element 31 is displaced in the X-axis direction, the convex portion 24a does not protrude from the slit portion 33a in a plan view. Therefore, if the sensor element 31 is tilted in the Z-axis direction due to unexpected vibration or impact including an external force in the out-of-plane direction or an inertial force, the sensor element 31 can be configured to always collide with the convex portion 24a at the slit portion 33a.

[0093] In the physical quantity sensor 1 of this embodiment, each of the multiple slits s1, s2, s3, and s4 extends in the X-axis direction. Therefore, the contact / sliding area between the sensor element 31 and the protruding portion 24a can be reduced, which makes it possible to prevent the sensor element 31 from sticking during use. In other words, a highly reliable physical quantity sensor 1 without failure can be realized.

[0094] In addition, in the physical quantity sensor 1 of this embodiment, the shape of the convex portion 24a is a circle or an ellipse in a plan view. Therefore, the degree of freedom in design can be improved.

[0095] 2. Embodiment 2 A physical quantity sensor 10 according to a second embodiment will be described with reference to FIGS. 7 to 10B. FIG. 7 is a plan view of the physical quantity sensor 10. FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 7. FIG. 10A is a plan view showing a modified example of the convex portion. FIG. 10B is a cross-sectional view showing a modified example of the convex portion. For ease of explanation, the lid 80 is made transparent in FIG. 7. In addition, in the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and explanations thereof may be omitted.

[0096] 7 is an acceleration sensor used to detect acceleration Ay in the Y-axis direction. Such a physical quantity sensor 10 has a support substrate 20, a lid body 80, and an element substrate 30 that is disposed between the support substrate 20 and the lid body 80 and has a sensor element 31, which is an acceleration sensor main body, provided thereon.

[0097] The physical quantity sensor 10 may include a detection circuit and an output circuit. The detection circuit performs detection processing on the signal output from the sensor element 31, and the output circuit outputs the signal obtained by the detection processing as a detection signal.

[0098] The details of the physical quantity sensor 10 of the second embodiment will be described below in the following sections: 2.1. Support Substrate 2.2. Lid 2.3. Element substrate 1. Conductor 2. Movable body 3. Fixed body 4. Slit section 1. Length a < Length b 2. Length G1 < Length G2 2.4. Variations

[0099] 2.1. Support Substrate 7, the support substrate 20 has a rectangular shape in a plan view. The support substrate 20 has a cavity 21 formed as a recess on the upper surface side. The cavity 21 is larger than the sensor element 31 in a plan view so as to include the sensor element 31 therein. The cavity 21 functions as a relief portion for preventing contact between the sensor element 31 and the support substrate 20.

[0100] In this embodiment, the support substrate 20 is a silicon substrate. However, the support substrate 20 may be a glass substrate or a ceramic substrate.

[0101] As shown in FIG. 8, the support substrate 20 has mounting portions 22a, 22b, and 22c, which are made up of large and small protrusions provided on the bottom surface of the cavity 21, and protrusions 24e and 24f along the Y-axis direction.

[0102] A sensor element 31 is joined to the mount portions 22a, 22b, and 22c. The protrusions 24e and 24f are stoppers for suppressing large displacement of the sensor element 31 in the Z-axis direction. Note that a large displacement in the Z-axis direction is a displacement in which the sensor element 31 would collide with the bottom surface of the cavity 21 if the protrusions 24e and 24f were not present. In addition, the Z-axis direction can be rephrased as an out-of-plane direction when a direction parallel to the main surface 32 of the element substrate 30 is defined as an in-plane direction.

[0103] The protrusions 24e, 24f are shorter than the mounts 22a, 22b, 22c, and are provided so as to have a predetermined distance between them and the sensor element 31 when stationary. When the sensor element 31 is displaced in the Z-axis direction due to unexpected vibration or impact including an external force in the out-of-plane direction or an inertial force, the convex portions 24e, 24f are the first to come into contact with the movable body 5 of the sensor element 31, thereby suppressing further displacement. Therefore, the occurrence of defects such as cracks or breaks in the movable body 5 of the sensor element 31 due to a large displacement of the movable body 5 of the sensor element 31 in the Z-axis direction is suppressed.

[0104] An insulating film 9 is provided on the upper surface of the support substrate 20. The element substrate 30 is bonded to the support substrate 20 with the insulating film 9 interposed therebetween.

[0105] 2.2. Lid As shown in FIG. 7, the cover 80 has a rectangular shape in a plan view. 8 and 9, the lid 80 has a cavity 81 formed as a recess on the lower surface side. The lid 80 is joined to the periphery of the element substrate 30. The cavity 81 of the lid 80 and the cavity 21 of the support substrate 20 form a storage space S. The sensor element 31 is stored in the storage space S.

[0106] In this embodiment, a glass substrate is used for the lid 80. The lid 80 may also be a silicon substrate or a ceramic substrate.

[0107] 8, wiring 7a is provided on the lower surface of the lid 80. Terminals 79 for external connection are provided on the upper surface of the lid 80. The terminal 79 is electrically connected to the wiring 7 a via a conductive member 78 that penetrates the lid 80 .

[0108] Although not shown, the wirings 7b and 7c are also provided on the lower surface of the lid body 80. Similarly to the wiring 7a, the wirings 7b and 7c are electrically connected to a terminal for external connection provided on the upper surface of the lid body 80 via a conductive member that penetrates the lid body 80.

[0109] 2.3. Element substrate As shown in FIG. 7, the element substrate 30 includes a sensor element 31 provided inside the cavity 21 in a plan view.

[0110] The sensor element 31 has a movable body 5, a fixed body 4, and a conductor 6. The fixed body 4 is provided in the sensor element 31 so that its position does not change. The movable body 5 is provided so that its position relative to the fixed body 4 can be changed along the Y-axis direction, which is the detection axis direction. The conductor 6 is electrically connected to a terminal for external connection.

[0111] The element substrate 30 is a silicon substrate doped with impurities such as phosphorus (P), boron (B), etc. The element substrate 30 is bonded to a support substrate 20 via an insulating film 9 to form an SOI (Silicon On Insulator) substrate. The sensor element 31 is formed by patterning an element substrate 30 made of a silicon substrate.

[0112] The peripheral portion of the element substrate 30 is joined to the peripheral portion of the support substrate 20 , and parts of the sensor element 31 are joined to the mount portions 22 a , 22 b , and 22 c of the support substrate 20 .

[0113] 2.3.1. Conductors The conductor 6 has conductive portions 61 , 62 , and 63 . As shown in FIG. 8, the conductive portion 61 is joined to the mount portion 22c of the support substrate 20 via an insulating film 9. Moreover, the conductive portion 61 is electrically connected to the wiring 7a of the lid body 80. The conductive portion 61 has a structure that protrudes in the Z-axis direction, and when the lid body 80 is joined, the protruding portion comes into contact with the wiring 7a, thereby being electrically connected to the wiring 7a.

[0114] The conductive portion 62 is electrically connected to the wiring 7b. The conductive portion 63 is electrically connected to the wiring 7c. Although not shown, the conductive portions 62 and 63 also have a structure protruding toward the lid 80 side, similar to the conductive portion 61.

[0115] As shown in FIG. 7, the conductive portion 61 is electrically connected to the fixed portions 52a and 52b of the movable body 5 via wiring 66. The conductive portion 62 is electrically connected to the fixed portion 441 of the first fixed body 44 and the fixed portion 471 of the fourth fixed body 47 via a wiring 67 . The conductive portion 63 is electrically connected to the fixed portion 451 of the second fixed body 45 and the fixed portion 461 of the third fixed body 46 via wiring 68 .

[0116] In this embodiment, the thickness of the conductive portions 61, 62, 63 of the sensor element 31 is increased and they protrude toward the lid body 80 side to come into contact with the wirings 7a, 7b, 7c. However, the present invention is not limited to this. A convex portion protruding toward the conductive portions 61, 62, 63 side may be provided on the underside of the lid body 80 to bring the wirings 7a, 7b, 7c into contact with the conductive portions 61, 62, 63.

[0117] 2.3.2. Movable objects The movable body 5 has fixed portions 52a and 52b, springs 53 and 54, and a movable portion 55. The fixed portions 52a and 52b, the springs 53 and 54, and the movable portion 55 are integrally formed with the conductive portion 61 and the wiring 66 and are electrically connected to each other.

[0118] As shown in FIG. 8, the lower surface of the fixing portion 52a is joined to the mounting portion 22a. As shown in FIG. 7, the spring 53 connects between the fixed portion 52a and the frame portion 551 of the movable portion 55. The spring 54 connects between the fixed portion 52 b and the frame portion 551 of the movable portion 55 .

[0119] The movable portion 55 is provided by the springs 53 and 54 so as to be displaceable along the Y-axis direction, which is the direction of the detection axis, in the in-plane direction of the main surface 32 of the element substrate 30. In other words, the movable portion 55 is provided so as to be displaceable in the Y-axis direction positive side and the Y-axis direction negative side in the Y-axis direction parallel to the main surface 32 of the element substrate 30. In this way, since movable part 55 is supported on both sides in the Y-axis direction by springs 53 and 54, the posture and behavior of movable part 55 are stable, and acceleration can be detected with higher accuracy.

[0120] In the second embodiment, the Y-axis direction is an example of a first direction, and the X-axis direction is an example of a second direction. The physical quantity sensor 10 is an inertial sensor having a detection axis in an in-plane direction of the main surface 32 of the element substrate 30. When the physical quantity sensor 10 is an acceleration sensor used to detect acceleration Ax in the X-axis direction, the X-axis direction corresponds to the first direction, and the Y-axis direction corresponds to the second direction.

[0121] Movable portion 55 has a frame-like shape in a plan view, and is provided so as to surround conductive body 6, fixed portions 52a and 52b, springs 53 and 54, and fixed body 4. The movable portion 55 has a frame portion 551 and a movable electrode 57. In the second embodiment, the movable electrode 57 is an example of a second electrode.

[0122] The movable electrode 57 has a plurality of first movable electrodes 571, a plurality of second movable electrodes 572, a plurality of third movable electrodes 573, and a plurality of fourth movable electrodes 574. Note that, in Fig. 7, an example in which the plurality is two for the plurality of first movable electrodes 571, the plurality of second movable electrodes 572, the plurality of third movable electrodes 573, and the plurality of fourth movable electrodes 574 is shown, but the plurality is not limited to two. Preferably, the plurality is eight.

[0123] Each of the multiple first movable electrodes 571 has multiple electrode fingers 571f. Each of the multiple second movable electrodes 572 has multiple electrode fingers 572f. Each of the multiple third movable electrodes 573 has multiple electrode fingers 573f. Each of the multiple fourth movable electrodes 574 has multiple electrode fingers 574f. 7 shows an example in which the plurality of electrode fingers 571f, the plurality of electrode fingers 572f, the plurality of electrode fingers 573f, and the plurality of electrode fingers 574f is eight, but the plurality of electrode fingers is not limited to eight.

[0124] The frame portion 551 is a portion of the four sides of the outer periphery of the movable portion 55. A slit portion 33e is provided in the center of the side on the positive side in the Y-axis direction of the frame portion 551. The slit portion 33e is provided at a position overlapping with the protrusion portion 24e in a plan view. Details of the slit portion 33e will be described later.

[0125] A slit portion 33f is provided in the center of the side on the negative side in the Y axis direction of the frame portion 551. The slit portion 33f is provided at a position overlapping with the protrusion portion 24f in a plan view. Details of the slit portion 33f will be described later. In this embodiment, the slit portion 33e and the slit portion 33f are disposed at two locations on both sides of the center of the frame portion 551 in the X-axis direction, with the fixed portions 52a and 52b and the springs 53 and 54 interposed therebetween.

[0126] 2.3.3. Fixed body The fixed body 4 has a first fixed body 44 , a second fixed body 45 , a third fixed body 46 , and a fourth fixed body 47 . The first fixed body 44 has a fixed portion 441 and a plurality of first fixed electrodes 442. In the second embodiment, the first fixed electrode 442 is an example of a first electrode.

[0127] The fixing portion 441 is joined to the mounting portion 22a. The multiple first fixed electrodes 442 are provided to extend toward the negative side in the X-axis direction from the fixed portion 441. Each of the multiple first fixed electrodes 442 has multiple electrode fingers 442f. The first fixed electrode 442 is provided to face the first movable electrode 571 on the negative side in the Y axis direction, with a length G1, which is the gap length between the electrodes, spaced therebetween.

[0128] The second fixed body 45 has a fixed portion 451 and a plurality of second fixed electrodes 452. In the second embodiment, the second fixed electrode 452 is an example of a first electrode. The fixing portion 451 is joined to the mounting portion 22a.

[0129] The multiple second fixed electrodes 452 are provided to extend toward the positive side in the X-axis direction from the fixed portion 451. Each of the multiple second fixed electrodes 452 has multiple electrode fingers 452f. The second fixed electrode 452 is provided to face the second movable electrode 572 on the positive side in the Y axis direction with a length G1 therebetween.

[0130] The third fixed body 46 has a fixed portion 461 and a plurality of third fixed electrodes 462. In the second embodiment, the third fixed electrode 462 is an example of a first electrode. The fixing portion 461 is joined to the mounting portion 22b.

[0131] The multiple third fixed electrodes 462 are provided to extend toward the positive side in the X-axis direction from the fixed portion 461. Each of the multiple third fixed electrodes 462 has multiple electrode fingers 462f. The third fixed electrode 462 is provided to face the third movable electrode 573 on the positive side in the Y axis direction with a length G1 therebetween.

[0132] The fourth fixed body 47 has a fixed portion 471 and a plurality of fourth fixed electrodes 472. In the second embodiment, the fourth fixed electrode 472 is an example of a first electrode.

[0133] The fixing portion 471 is joined to the mounting portion 22b. The multiple fourth fixed electrodes 472 are provided to extend toward the negative side in the X-axis direction from the fixed portion 471. Each of the multiple fourth fixed electrodes 472 has multiple electrode fingers 472f. The fourth fixed electrode 472 is provided to face the fourth movable electrode 574 on the negative side in the Y axis direction with a length G1 therebetween.

[0134] When acceleration in the positive Y-axis direction is applied to such sensor element 31, the movable portion 55 is displaced in the negative Y-axis direction while elastically deforming the springs 53 and 54 based on the magnitude of the acceleration.

[0135] As a result of this displacement, the length G1, which is the gap length between the first movable electrode 571 and the first fixed electrode 442, the second movable electrode 572 and the second fixed electrode 452, the third movable electrode 573 and the third fixed electrode 462, and the fourth movable electrode 574 and the fourth fixed electrode 472, changes.

[0136] This change in length G1 changes the magnitude of each of the electrostatic capacitances between the first movable electrode 571 and the first fixed electrode 442, between the second movable electrode 572 and the second fixed electrode 452, between the third movable electrode 573 and the third fixed electrode 462, and between the fourth movable electrode 574 and the fourth fixed electrode 472.

[0137] The physical quantity sensor 10 of the second embodiment is provided so as to be able to detect these changes in capacitance. The detection circuit and the output circuit output detection signals based on these changes in capacitance. Thus, the acceleration Ay in the Y-axis direction can be detected.

[0138] Furthermore, in physical quantity sensor 10 of embodiment 2, the area in which electrode finger 442f and electrode finger 571f, electrode finger 452f and electrode finger 572f, electrode finger 462f and electrode finger 573f, and electrode finger 472f and electrode finger 574f face each other in the X-axis direction changes due to the change in length G1. Then, based on the change in capacitance due to this change in area, acceleration Ay in the Y-axis direction can also be detected.

[0139] 2.3.4. Slit section As shown in FIG. 7, the slits 33e and 33f have the same configuration as the slits 33a, 33b, 33c and 33d of the first embodiment.

[0140] Each of the slits s1, s2, s3, and s4 is a slit whose longitudinal direction extends in the Y-axis direction. Each of the slits s1, s2, s3, and s4 is a through-hole that penetrates between the upper and lower surfaces of the element substrate 30 in the Z-axis direction.

[0141] The portions with the slits 33e and 33f have higher flexibility than the other portions, in other words, the portions where the slits 33e and 33f are not provided. Therefore, when the sensor element 31 is displaced in the Z-axis direction due to unexpected vibration or impact including an external force in the out-of-plane direction or an inertial force, the protrusion 24e collides with the highly flexible slit portion 33e in the movable portion 55, and the impact is absorbed by the slit portion 33e, thereby preventing the movable portion 55 from cracking or breaking. In other words, the robustness against a strong impact can be improved. The same applies to the case where the protrusion 24f collides with the slit portion 33f. Furthermore, when contact between the sensor element 31 and the protruding portion 24e is repeated many times due to long-term vibration, a sliding portion is formed between the sensor element 31 and the protruding portion 24e. Therefore, repeated contact and sliding between the two substances may cause sticking between the substances. In the second embodiment, the contact area or sliding area between the sensor element 31 and the protruding portion 24e can be reduced compared to a case where the slit portions 33a, 33f are not provided. In other words, sticking during use of the sensor element 31 can be reduced.

[0142] The longitudinal direction of the slits s1, s2, s3, and s4 may be the X-axis direction. However, similarly to the first embodiment, the longitudinal direction of the slits s1, s2, s3, and s4 may be the same as the detection axis direction of the physical quantity sensor 10 to further suppress sticking of the sensor element 31. Therefore, when the physical quantity sensor 10 is an acceleration sensor used to detect acceleration Ay in the Y-axis direction, it is preferable that the longitudinal direction of the slits s1, s2, s3, and s4 be in the Y-axis direction rather than in the X-axis direction. Similarly, when the physical quantity sensor 10 is an acceleration sensor used to detect acceleration Ax in the X-axis direction, it is preferable that the longitudinal direction of the slits s1, s2, s3, and s4 be in the X-axis direction rather than in the Y-axis direction.

[0143] 2.3.4.1. Length a < Length b 9, in the second embodiment, the relationship between length a and length b is length a<length b, as in the first embodiment. Furthermore, the total length 3a (length a×3) of the inter-slit extending portions b1, b2, and b3 is configured to be smaller than length b. The definitions of length a and length b are the same as in the first embodiment.

[0144] The protrusion 24f is provided at a position overlapping with the inter-slit extending portions b1, b2, and b3. When the sensor element 31 is displaced in the Z-axis direction due to unexpected vibration or impact including an external force in the out-of-plane direction or an inertial force and comes into contact with the convex portion 24f, the only part of the sensor element 31 that comes into contact with the convex portion 24f is the portion of length a of the inter-slit extension portions b1, b2, and b3. This reduces the area of ​​contact between the sensor element 31 and the protruding portion 24f, thereby preventing the sensor element 31 from sticking to the protruding portion 24f.

[0145] Similarly, even if the sensor element 31 and the convex portion 24f are displaced in the X-axis direction while remaining in contact with each other and slide against each other, the only part of the sensor element 31 that slides against the convex portion 24f is the part of length a of the inter-slit extension portions b1, b2, and b3. This reduces the area of ​​the sliding portion where the sensor element 31 and the protruding portion 24f come into contact with each other, thereby preventing the sensor element 31 from sticking to the protruding portion 24f.

[0146] 2.3.4.2. Length G1 < Length G2 In the second embodiment, similarly to the first embodiment, the relationship between the length G1 and the length G2 is length G1<length G2.

[0147] Length G1 is the gap length between the first fixed electrode 442 and the first movable electrode 571, between the second fixed electrode 452 and the second movable electrode 572, between the third fixed electrode 462 and the third movable electrode 573, and between the fourth fixed electrode 472 and the fourth movable electrode 574, as shown in FIG. 7.

[0148] 7 and 10A, length G1 is the gap length between first fixed electrode 442 and the tips of electrode fingers 571f of first movable electrode 571. Note that length G1 may be the gap length between the tips of electrode fingers 442f of first fixed electrode 442 and first movable electrode 571. When the gap length between first fixed electrode 442 and the tips of electrode fingers 571f of first movable electrode 571 and the gap length between the tips of electrode fingers 442f of first fixed electrode 442 and first movable electrode 571 are different, the shorter of the two is taken as length G1. This also applies to the respective gap lengths between the second fixed electrode 452 and the second movable electrode 572, between the third fixed electrode 462 and the third movable electrode 573, and between the fourth fixed electrode 472 and the fourth movable electrode 574.

[0149] Similarly to the first embodiment, the length G2 is the length between the ends of the convex portions 24e, 24f and the ends of the slits s1, s2, s3, s4 in the Y-axis direction which is the detection axis direction. Although the length between the ends of the slits s1, s2, s3, and s4 on both sides of the protrusions 24e and 24f is set to the length G2, only one side may be set to the length G2. In this case, similarly to the first embodiment, it is preferable to set the length G2 on the side farther from the center of gravity of the sensor element 31.

[0150] The maximum displacement range of the sensor element 31 in the Y-axis direction is a length G1 which is the gap length between the electrodes. Therefore, even if the sensor element 31 is displaced in the Y-axis direction, the protrusions 24e, 24f do not protrude from the slits 33e, 33f in plan view. Therefore, similarly to the first embodiment, it is possible to prevent the sensor element 31 from sticking to the protrusions 24e and 24f.

[0151] The physical quantity sensor 10 may include a detection circuit and an output circuit. The detection circuit performs detection processing on the signal output from the sensor element 31, and the output circuit outputs the signal obtained by the detection processing as a detection signal.

[0152] 2.4. Variations The above-described embodiment may be modified in various ways. Specific modifications will be described below as examples. As shown in FIGS. 10A and 10B, a protrusion 24g provided to overlap with a slit 33g may be connected to the mount 22d.

[0153] In the slit portion 33g, the slits s1, s2, s3, and s4 may be connected on one side. In this case, it is preferable to connect the slits on the center of gravity side of the physical quantity sensor 10.

[0154] As described above, according to the physical quantity sensor 10 of this embodiment, in addition to the effects of the above embodiment, the following effects can be obtained. The physical quantity sensor 10 of this embodiment includes a support substrate 20 having a convex portion 24e, a fixed body 4 fixed to the support substrate 20 and having a first fixed electrode 442 as a first electrode, a fixed portion 52a fixed to the support substrate 20, a spring 53 connected to the fixed portion 52a, and a first movable electrode 571 connected to the spring 53 and serving as a second electrode facing the first fixed electrode 442, and the movable body 5 includes a plurality of slits s1, s2, s3, s4 that overlap with the convex portion 24e in a planar view.

[0155] In this way, since the movable portion 55 includes the multiple slits s1, s2, s3, and s4 that overlap with the protrusion 24e in a plan view, robustness against strong impact can be improved, and a highly reliable physical quantity sensor 10 having excellent impact resistance can be realized.

[0156] In addition, in the physical quantity sensor 10 of this embodiment, in the X-axis direction, which is a second direction intersecting the Y-axis, the length a between adjacent slits s1 and s2 among the multiple slits s1, s2, s3, and s4 is smaller than the length b of the convex portion 24e. Therefore, the sensor element 31 can be prevented from sticking to the protrusion 24e.

[0157] In addition, in the physical quantity sensor 10 of this embodiment, the length G2 between the end of the convex portion 24e and the ends of the slits s1, s2, s3, and s4 in the Y-axis direction is greater than the length G1 between the first fixed electrode 442 and the first movable electrode 571. Therefore, even if the sensor element 31 is displaced in the Y-axis direction, the convex portion 24e does not protrude from the slit portion 33e in a plan view. Therefore, if the sensor element 31 is tilted in the Z-axis direction due to unexpected vibration or impact including an external force in the out-of-plane direction or an inertial force, the sensor element 31 can be configured to always collide with the convex portion 24e at the slit portion 33e.

[0158] Furthermore, in the physical quantity sensor 10 of this embodiment, each of the multiple slits s1, s2, s3, and s4 extends in the Y-axis direction. Therefore, the sensor element 31 can be prevented from sticking to the protrusion 24e.

[0159] 3. Embodiment 3 3.1. Overview of the Inertial Measurement Unit Next, an inertial measurement unit 300 including the physical quantity sensor 1 of the first embodiment or the physical quantity sensor 10 of the second embodiment will be described with reference to FIGS. Fig. 11 is an exploded perspective view showing a schematic configuration of an inertial measurement unit (IMU) 300 according to this embodiment. Fig. 12 is a perspective view of a board mounted with the packaged physical quantity sensor 1 or physical quantity sensor 10, which is mounted on the inertial measurement unit 300.

[0160] The inertial measurement unit 300 is mounted on a wearable device such as an automobile, a robot, a smartphone, or a portable activity monitor, and is used as a device for detecting the attitude, behavior, etc. of the wearable device.

[0161] As shown in FIG. 11, the inertial measurement device 300 includes an outer case 301, a joint member 310, and a sensor module 325, and is configured such that the sensor module 325 is fitted or inserted inside the outer case 301 with the joint member 310 interposed therebetween.

[0162] Outer case 301 is a box-shaped container with a rectangular parallelepiped exterior and no lid, and its interior is an internal space surrounded by walls. The material of outer case 301 is, for example, aluminum. However, other metals such as zinc or stainless steel, resin, or a composite material of metal and resin may also be used.

[0163] A through hole 302 is formed near each of two diagonally opposite vertices on the top surface of the outer case 301. The through hole 302 is used when attaching the inertial measurement unit 300 to the device to which it is attached. The sensor module 325 is composed of an inner case 320 and a circuit board 315 .

[0164] Inner case 320 is a member that supports circuit board 315, and has a shape that fits inside outer case 301. As the material for inner case 320, the same material as that for outer case 301 can be used. The bottom surface of inner case 320 is formed with recess 331 for preventing contact with circuit board 315 and opening 321 for exposing connector 316 .

[0165] The configuration of a circuit board 315 on which the packaged physical quantity sensor 1 or the physical quantity sensor 10 is mounted will be described with reference to FIG. 12, the circuit board 315 is a multi-layer board with multiple through holes formed therein, and is made of a glass epoxy board. However, it is not limited to a glass epoxy board, and a rigid board such as a composite board or a ceramic board may also be used.

[0166] On the top and side surfaces of the circuit board 315, a connector 316, a physical quantity sensor 1, and angular velocity sensors 317x, 317y, and 317z are mounted. The connector 316 is a plug-type connector and has two rows of connection terminals arranged at equal pitch in the X-axis direction. In this embodiment, the connector has two rows of connection terminals with 10 pins per row, for a total of 20 pins, but the number of connection terminals may be changed as appropriate depending on the design specifications.

[0167] The angular velocity sensor 317z is a gyro sensor that detects a one-axis angular velocity in the Z-axis direction. As a suitable example, a vibration gyro sensor is used that uses a quartz crystal as an oscillator and detects the angular velocity from the Coriolis force applied to a vibrating object. Note that the present invention is not limited to a vibration gyro sensor, and a sensor using ceramic or silicon as an oscillator may also be used.

[0168] Furthermore, angular velocity sensor 317x that detects angular velocity along one axis in the X-axis direction is mounted on a side surface of circuit board 315 in the X-axis direction, with the mounting surface perpendicular to the X-axis. Similarly, angular velocity sensor 317y that detects angular velocity along one axis in the Y-axis direction is mounted on a side surface of circuit board 315 in the Y-axis direction, with the mounting surface perpendicular to the Y-axis.

[0169] In this embodiment, each of the angular velocity sensors 317x, 317y, and 317z is configured as a single chip, but the present invention is not limited to this configuration. For example, a single-chip sensor device in which the angular velocity sensors 317x, 317y, and 317z are packaged may be used.

[0170] The physical quantity sensor 1 may be a physical quantity sensor 10. In addition, a plurality of physical quantity sensors 1 or physical quantity sensors 10 may be mounted to detect acceleration in two axial directions, for example, Z-axis and Y-axis directions, or Z-axis and X-axis directions, or three axial directions, for example, X-axis, Y-axis, and Z-axis directions.

[0171] A control IC 319 serving as a control unit is mounted on the lower surface of the circuit board 315. The control IC 319 is an MCU (Micro Controller Unit) and is configured as a one-chip IC.

[0172] The control IC 319 reads and processes the detection signal from the physical quantity sensor 1 or the physical quantity sensor 10, and generates detection data based on the detection signal. The control IC 319 also performs various types of arithmetic processing on the detection signal. The arithmetic processing is, for example, an averaging process. The control IC 319 may also have a function of correcting temperature characteristics, misalignment, and the like.

[0173] Circuit board 315 includes a storage unit such as a non-volatile memory (not shown). The storage unit stores a program that specifies the sequence and content for detecting acceleration and angular velocity, a program that digitizes the detected data and incorporates it into packet data, associated data, etc. Circuit board 315 also has a number of other electronic components mounted thereon.

[0174] According to such an inertial measurement unit 300, since the physical quantity sensor 1 or the physical quantity sensor 10 is used, it is possible to provide an inertial measurement unit 300 that has excellent shock resistance and improved reliability.

[0175] Although the preferred embodiment has been described above, the present invention is not limited to the above embodiment. Furthermore, the configuration of each part of the present invention can be replaced with any configuration that exhibits the same function as the above embodiment, and any configuration can be added. [Explanation of symbols]

[0176] 1,10...Physical quantity sensor, 2,20...Support substrate, 21...Cavity, 22,22a,22b,22c...Mounting portion, 23a,23b,23c...Groove portion, 24a,24b,24c,24d,24e,24f,24g...Convex portion, 3,30...Element substrate, 31...Sensor element, 32...Main surface, 33a,33b,33c,33d,33e,33f,33g...Slit portion, 35...Bonding material, 4...Fixed body, 41...First fixed body, 42...Second fixed body, 44...First fixed body, 45...Second fixed body, 46...Third fixed body, 47...Fourth fixed body, 411...First stator bar, 412, 412a, 412b...first fixed electrode, 413...fixed part, 421...second stator bar, 422,422a,422b...second fixed electrode, 423...fixed part, 441...fixed part, 442...first fixed electrode, 442f...electrode finger, 451...fixed part, 452...second fixed electrode, 452f...electrode Finger, 461...fixed part, 462...third fixed electrode, 462f...electrode finger, 471...fixed part, 472...fourth fixed electrode, 472f...electrode finger, 5...movable body, 51...suspension bar, 52,52a,52b...fixed part, 55...movable part, 56,57...movable electrode, 551...frame part, 552...first Y-axis extension part , 553...first X-axis extending part, 554...second Y-axis extending part, 555...second X-axis extending part, 556...first protruding part, 557...second protruding part, 558... First opening, 559...Second opening, 561,561a,561b...First movable electrode, 562,562a,562b...Second movable electrode, 571 ...first movable electrode, 571f...electrode finger, 572...second movable electrode, 572f...electrode finger, 573...third movable electrode, 573f...electrode finger, 574...fourth movable electrode, 574f...electrode finger, 6...conductor, 61,62,63...conductor, 66,67,68,7,7a,7b,7c,71,72,7 3...wiring, 75, 76, 77...external connection terminal, 78...conductive member, 79...terminal, 8, 80...lid, 81...cavity, 82...communication hole, 83...sealing member, 9...insulating film, 300...inertial measurement device, 301...outer case, 302...through hole, 310...joint member, 315...circuit board, 316...connector, 317x, 317y, 317z...angular velocity sensor, 319...control IC, 320...inner case, 321...opening, 325...sensor module, 331...recess, s1, s2, s3, s4...slit, b1, b2, b3...extension between slits, c1, c2,c3...contact part, G1...length, S...storage space, L...center axis.

Claims

1. A support substrate having a protrusion; a fixed body fixed to the support substrate and having a first electrode; a movable body having a fixed portion fixed to the supporting substrate, a spring connected to the fixed portion, and a second electrode connected to the spring and facing the first electrode, the movable body being displaced along a first direction parallel to a main surface of the supporting substrate; The movable body includes a plurality of slits that overlap with the convex portion in a plan view. Physical quantity sensor.

2. In a second direction intersecting the first direction, a length between adjacent slits among the plurality of slits is shorter than a length of the protrusion. The physical quantity sensor according to claim 1 .

3. In the first direction, a length between an end of the protrusion and an end of the slit is greater than a length between the first electrode and the second electrode. The physical quantity sensor according to claim 1 .

4. Each of the plurality of slits extends in the first direction. The physical quantity sensor according to claim 1 .

5. In a plan view, the shape of the convex portion is a circle or an ellipse. The physical quantity sensor according to claim 1 .

6. An inertial measurement device comprising the physical quantity sensor according to claim 1 .

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