Physical quantity sensor, inertial measurement device, and manufacturing method

Abstract

Disclosed is a physical quantity sensor, an inertial measurement device, and a manufacturing method, which can avoid adverse situations accompanying with mass unevenness of a movable body. The physical quantity sensor detects a physical quantity in a third direction, and includes a fixed portion fixed to a substrate, a support beam having one end connected to the fixed portion, and a movable body. The movable body has a movable electrode portion and a frame portion. A first fixed electrode group and a second fixed electrode group are provided in the fixed electrode portion. A first movable electrode group and a second movable electrode group are provided in the movable electrode portion. Furthermore, a first recessed portion recessed in the third direction is provided in the first movable electrode group, a second recessed portion recessed in the third direction is provided in the second fixed electrode group, and a third recessed portion recessed in the third direction is provided in a region of the frame portion on the side of the second movable electrode group.

Description

Technical Field

[0001] This invention relates to physical quantity sensors, inertial measurement devices, and manufacturing methods. Background Technology

[0002] Patent Document 1 discloses a physical quantity sensor comprising at least one rotor and at least two stators. In this physical quantity sensor, at least a portion of the rotor and stator is recessed from a first surface of the device layer to at least two different depths. Furthermore, at least a portion of the rotor and stator is recessed from a second surface of the device layer to at least two different depths.

[0003] Patent Document 1: Japanese Patent Publication No. 2018-515353

[0004] According to the physical quantity sensor disclosed in Patent Document 1, when there are two or more stators, the thickness of the comb-tooth electrode of the rotor is changed for each rotor corresponding to each stator. Therefore, the balance of the movable body relative to the rotation axis is disrupted, and the sensitivity of the other axis may increase. Summary of the Invention

[0005] One aspect of the present invention relates to a physical quantity sensor that detects a physical quantity in the third direction when mutually orthogonal directions are defined as a first direction, a second direction, and a third direction. The physical quantity sensor includes: a fixing part fixed to a substrate; a support beam connected at one end to the fixing part; a fixed electrode part disposed on the substrate and including a first fixed electrode group and a second fixed electrode group; and a movable body having a movable electrode part and a frame part. The movable electrode part is provided with a first movable electrode group in which each movable electrode faces each fixed electrode of the first fixed electrode group and a second movable electrode group in which each movable electrode faces each fixed electrode of the second fixed electrode group. The frame part connects the movable electrode part and the other end of the support beam. A first recess recessing towards the third direction is provided in the first movable electrode group, a second recess recessing towards the third direction is provided in the second fixed electrode group, and a third recess recessing towards the third direction is provided in the region on the second movable electrode group side of the frame part.

[0006] In addition, other aspects of the present invention relate to an inertial measurement device, which includes the physical quantity sensor described above and a control unit that controls the device based on a detection signal output from the physical quantity sensor.

[0007] In addition, other aspects of the present invention relate to a manufacturing method for a physical quantity sensor. When three mutually orthogonal directions are designated as a first direction, a second direction, and a third direction, the physical quantity sensor detects a physical quantity in the third direction. The manufacturing method includes: a fixed electrode portion forming step on a substrate; and a movable body forming step on a movable body. The physical quantity sensor includes a fixed portion fixed to the substrate, one end of a support beam connected to the fixed portion, the fixed electrode portion disposed on the substrate, and including a first fixed electrode group and a second fixed electrode group. The movable body includes: a movable electrode portion, on which each movable electrode and the first fixed electrode are disposed. The assembly comprises a first movable electrode group with each fixed electrode facing the first movable electrode group and a second movable electrode group with each movable electrode facing the fixed electrodes of the second fixed electrode group; and a frame portion connecting the movable electrode portion to the other end of the support beam. In the fixed electrode portion forming process, the second fixed electrode group is formed such that a second recess is provided in the second fixed electrode group in a third direction. In the movable body forming process, the first movable electrode group is formed such that a first recess is provided in the first movable electrode group in a third direction. The movable body is formed such that a third recess is provided in the region on the second movable electrode group side of the frame portion in a third direction. Attached Figure Description

[0008] Figure 1 This is a structural example of the physical quantity sensor in this embodiment.

[0009] Figure 2 It is a three-dimensional diagram used to illustrate the three-dimensional shape of the first concave part.

[0010] Figure 3 It is a three-dimensional diagram used to illustrate the three-dimensional shape of the second concave part.

[0011] Figure 4 This is a diagram illustrating the operation of the testing department.

[0012] Figure 5 This is an illustration of the effect of mass non-uniformity on a movable body.

[0013] Figure 6 This is an illustration of the effect of mass non-uniformity on a movable body.

[0014] Figure 7 This is an illustration of the effect of mass non-uniformity on a movable body.

[0015] Figure 8 This is a top view showing the first detailed example of a physical quantity sensor.

[0016] Figure 9This is a top view showing a second detailed example of a physical quantity sensor.

[0017] Figure 10 This is a top view of a modified example of a second detailed example of a physical quantity sensor.

[0018] Figure 11 It is an exploded three-dimensional diagram showing the general structure of the inertial measurement device of a physical quantity sensor.

[0019] Figure 12 This is a three-dimensional view of the circuit board of an inertial measurement device.

[0020] Figure 13 This is a top view of the physical quantity sensor in this embodiment.

[0021] Figure 14 This is an explanatory diagram of the manufacturing method of the physical quantity sensor of this embodiment.

[0022] Figure 15 This is an explanatory diagram of the manufacturing method of the physical quantity sensor of this embodiment.

[0023] Figure 16 This is an explanatory diagram of the manufacturing method of the physical quantity sensor of this embodiment.

[0024] Figure 17 This is an explanatory diagram of the manufacturing method of the physical quantity sensor of this embodiment.

[0025] Figure 18 This is an explanatory diagram of the manufacturing method of the physical quantity sensor of this embodiment.

[0026] Figure 19 This is an explanatory diagram of the manufacturing method of the physical quantity sensor of this embodiment.

[0027] Figure 20 This is an explanatory diagram of the manufacturing method of the physical quantity sensor of this embodiment.

[0028] Figure 21 This is an explanatory diagram of the manufacturing method of the physical quantity sensor of this embodiment.

[0029] Figure 22 This is an explanatory diagram of the manufacturing method of the physical quantity sensor of this embodiment.

[0030] Explanation of reference numerals in the attached figures

[0031] 1…Physical quantity sensor, 2…Substrate, 10…Fixed electrode section, 10A…First fixed electrode group, 10B…Second fixed electrode group, 11…Fixed electrode, 12…Fixed electrode, 14…Fixed electrode, 20…Modible electrode section, 20A…First movable electrode group, 20B…Second movable electrode group, 21…Modible electrode, 22…Modible electrode, 24…Modible electrode, 30…Frame section, 31…First part, 32…Second part, 40…Fixed part, 42…Support beam, 43…Support beam, 50… Fixed electrode section, 50A…first fixed electrode group, 50B…second fixed electrode group, 51…fixed electrode, 52…fixed electrode, 60…movable electrode section, 60A…first movable electrode group, 60B…second movable electrode group, 61…movable electrode, 62…movable electrode, 70…frame section, 72…second part, 82…support beam, 83…support beam, 91…first element section, 92…second element section, 100…first detection element, 200…silicon substrate, 202…cavity, 204…surface oxidation 206… Embedded insulating film, 208… Wafer, 210… SiO2 layer, 214… Photoresist, 2000… Inertial measurement unit, 2100… Housing, 2110… Threaded hole, 2200… Connecting component, 2300… Sensor module, 2310… Inner shell, 2311… Recess, 2312… Opening, 2320… Circuit board, 2330… Connector, 2340x… Angular velocity sensor, 2340y… Angular velocity sensor, 2340z… Angular velocity sensor, 2350… Accelerometer sensor unit, DR1…first direction, DR2…second direction, DR3…third direction, DR4…fourth direction, F1…inertial force, F2…inertial force, F3…inertial force, F4…inertial force, I…inertial torque, IC2360…control, LFA…wiring, LFB…wiring, LV…wiring, MB…movable body, MB1…first movable body, MB2…second movable body, PFA…pad, PFB…pad, PV…pad, QV…differential amplifier circuit, R1…first recess, r 20A ...position vector, r 20B …position vector, R2…second concave, R3…third concave, R4…first concave, R5…second concave, R6…third concave, Z…detection part, ZA…detection part, ZB…detection part, ax…acceleration, ay…acceleration, az…acceleration, h1…depth, ωx…angular velocity. Detailed Implementation

[0032] The following describes this embodiment. Furthermore, the embodiments described below do not unduly limit the scope of the claims. Also, not all of the components described in this embodiment are necessarily essential elements.

[0033] 1. Physical quantity sensor

[0034] Regarding the structural example of the physical quantity sensor 1 in this embodiment, an acceleration sensor that detects acceleration in the vertical direction is given as an example, referring to... Figure 1 Please provide an explanation. Figure 1 This is a top view of the physical quantity sensor 1 when viewed from above in a direction orthogonal to the substrate 2. The physical quantity sensor 1 is a MEMS (Micro Electro Mechanical Systems) device, such as an inertial sensor.

[0035] In addition, Figure 1 The following Figures 2 to 10 as well as Figures 13-22 For ease of explanation, the dimensions of each component and the spacing between them are shown schematically; not all constituent elements are shown. For example, electrode wiring and electrode terminals are omitted from the illustration. Furthermore, the following explanation primarily uses the case where the physical quantity detected by physical quantity sensor 1 is acceleration, but the physical quantity is not limited to acceleration; it can also be other physical quantities such as velocity, pressure, displacement, angular velocity, or gravity. Physical quantity sensor 1 can also be used as a pressure sensor or a MEMS switch, etc. Additionally, in Figure 1 In this design, mutually orthogonal directions are designated as the first direction DR1, the second direction DR2, and the third direction DR3. The first direction DR1, the second direction DR2, and the third direction DR3 are, for example, the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively, but are not limited to these. For example, the third direction DR3 corresponding to the Z-axis direction is, for example, a direction orthogonal to the substrate 2 of the physical quantity sensor 1, such as a vertical direction. Furthermore, the fourth direction DR4 is the opposite direction of the third direction DR3, for example, a direction on the negative side of the Z-axis direction. The first direction DR1 corresponding to the X-axis direction and the second direction DR2 corresponding to the Y-axis direction are directions orthogonal to the third direction DR3, along the plane of the first direction DR1 and the second direction DR2, i.e., the XY plane, for example, along a horizontal plane. Furthermore, "orthogonal" includes not only intersections at 90° but also intersections at an angle slightly inclined from 90°.

[0036] Substrate 2 may be, for example, a silicon substrate made of semiconductor silicon or a glass substrate made of glass materials such as borosilicate glass. However, there are no particular limitations on the constituent materials of substrate 2, and quartz substrates or SOI (Silicon On Insulator) substrates may be used.

[0037] Moreover, such as Figure 1As shown, the physical quantity sensor 1 of this embodiment includes a fixed electrode part 10, a movable body MB, a fixing part 40, and support beams 42 and 43. Moreover, the movable body MB includes a movable electrode part 20 and a frame part 30. The frame part 30 includes two first parts 31 extending in the second direction DR2 as the long side direction and one second part 32 extending in the first direction DR1 as the long side direction.

[0038] The first detection element 100 of the physical quantity sensor 1 is composed of the fixed electrode part 10, the movable electrode part 20, the frame part 30, the fixing part 40, and the support beams 42 and 43. The first detection element 100 detects physical quantities, such as acceleration, in the third direction DR3, which is the Z-axis direction, in the detection part ZA and the detection part ZB.

[0039] The fixed electrode section 10 includes a first fixed electrode group 10A and a second fixed electrode group 10B. The first fixed electrode group 10A and the second fixed electrode group 10B are respectively disposed on the substrate 2. Furthermore, the first fixed electrode group 10A and the second fixed electrode group 10B are respectively fixed to the substrate 2 by a fixing part. The first fixed electrode group 10A includes a plurality of fixed electrodes 11, and the second fixed electrode group 10B includes a plurality of fixed electrodes 12. These plurality of fixed electrodes 11 and 12 extend, for example, along a second direction DR2, which is the Y-axis direction. That is, the plurality of fixed electrodes 11 are configured in a comb-like shape, and they constitute the first fixed electrode group 10A. Similarly, the plurality of fixed electrodes 12 are configured in a comb-like shape, and they constitute the second fixed electrode group 10B. In the following description, the fixed electrodes 11 of the first fixed electrode group 10A and the fixed electrodes 12 of the second fixed electrode group 10B are appropriately referred to as fixed electrodes 14.

[0040] The movable electrode section 20 includes a first movable electrode group 20A and a second movable electrode group 20B. The first movable electrode group 20A includes a plurality of movable electrodes 21, and the second movable electrode group 20B includes a plurality of movable electrodes 22. These plurality of movable electrodes 21, 22 extend from the second portion 32 of the frame section 30, for example, along a second direction DR2, which is the Y-axis direction. Moreover, the plurality of movable electrodes 21 are arranged in a comb-like shape, constituting the first movable electrode group 20A, and the plurality of movable electrodes 22 are arranged in a comb-like shape, constituting the second movable electrode group 20B. Furthermore, each movable electrode 21 of the first movable electrode group 20A is configured to face each fixed electrode 11 of the first fixed electrode group 10A in a first direction DR1, which is the X-direction. In addition, each movable electrode 22 of the second movable electrode group 20B is configured to face each fixed electrode 12 of the second fixed electrode group 10B in the first direction DR1. Furthermore, the portions of the fixed electrode 11 and the movable electrode 21 arranged opposite each other in the first direction DR1 correspond to the detection section ZA of the first detection element 100, and the portions of the fixed electrode 12 and the movable electrode 22 arranged opposite each other in the first direction DR1 correspond to the detection section ZB of the first detection element 100. In the following description, the movable electrode 21 of the first movable electrode group 20A and the movable electrode 22 of the second movable electrode group 20B will be collectively referred to as the movable electrode 24.

[0041] The movable body MB moves about the first direction DR1 along the support beams 42 and 43 as the axis of rotation.

[0042] Here, the support beams 42 and 43 are, for example, torsion springs, and one end of each of the support beams 42 and 43 is fixed to the base plate 2 by a fixing part 40. Figure 1 In this configuration, two support beams 42 and 43 are provided along the first direction DR1, with support beam 42 extending from the fixed part 40 to the opposite side in the first direction DR1 and support beam 43 extending from the fixed part 40 to the side in the first direction DR1. Furthermore, the frame part 30 of the movable body MB is connected at both ends to the other ends of the support beams 42 and 43, i.e., the ends not connected to the fixed part 40. Thus, the movable body MB is formed in a roughly U-shape by the two first parts 31 and one second part 32 of the frame part 30, and is connected to the fixed part 40 via the support beams 42 and 43.

[0043] This constructs a movable body MB, with support beams 42 and 43 designed to rotate around a rotation axis. These beams are subjected to a force in the third direction DR3, causing them to twist along the axis of the first direction DR1, thus enabling the movable body MB to swing in the third direction DR3. Furthermore, a first detection element 100 is implemented, which is a so-called one-sided seesaw structure where the movable body MB swings with the fixed part 40 as a retainer.

[0044] In addition, the frame part 30 is designed with a large mass in the front part, i.e. the second part 32, resulting in a larger moment of inertia I around the rotation axis.

[0045] In addition, Figure 1 In the physical quantity sensor 1 shown, a first recess R1 is provided on the movable electrode 21 of the first movable electrode group 20A. Figure 2 This is a three-dimensional diagram illustrating the solid shape of the first recess R1. For example... Figure 2 As shown, the thickness of the movable electrode 21 in the third direction DR3 is locally recessed. Specifically, in the second direction DR2, the thickness in the third direction DR3 is thinner. Figure 2 The range shown in a. Thus, the movable electrode 21 has the same thickness as the third-direction DR3 of the frame portion 30 within a certain range from the connection portion to the second part 32 of the frame portion 30, but the thickness of the third-direction DR3 becomes thinner mainly in the region opposite the fixed electrode 11 of the first fixed electrode group 10A. Furthermore, the detection unit ZA includes a fixed electrode 11 and a movable electrode 21 with different thicknesses on the third-direction DR3.

[0046] In addition, Figure 1 The fixed electrode 12 of the second fixed electrode group 10B of the physical quantity sensor 1 shown is provided with a second recess R2. Figure 3 This is a three-dimensional diagram illustrating the shape of the second concave portion R2. For example... Figure 3 As shown, the thickness of the fixed electrode 12 on its third-direction DR3 is locally recessed. Specifically, in the area formed by... Figure 3 In the region shown in b, the thickness of the fixed electrode 12 on the third-direction DR3 is the same as the thickness of the root portion of the comb electrode of the second fixed electrode group 10B. However, the thickness of the fixed electrode 12 on the third-direction DR3 outside the region shown in b is thinner. Moreover, the detection unit ZB includes a fixed electrode 12 and a movable electrode 22 with different thicknesses on the third-direction DR3. Furthermore, the fixed electrodes 11 and 12 are, for example, about 10 μm to 40 μm thick.

[0047] Moreover, in Figure 1 In the physical quantity sensor 1 shown, a third recess R3 is provided in a portion of the second part 32 of the frame portion 30 of the movable body MB. Specifically, as Figure 3 As shown in the perspective view, the third recess R3 is a recessed portion of the second part 32 of the frame part 30 on the third direction DR3 side. Furthermore, as will be described later... Figures 14-22 The details are explained in the text, but in this embodiment, it is assumed that the first recess R1, the second recess R2, and the third recess R3 are formed by a joint etching process and all have the same depth.

[0048] Figure 4 This is an operational diagram illustrating the detection units ZA and ZB in the first detection element 100. Figure 4 From left to right, the initial state and the state in which acceleration has occurred are shown in cross-sectional views along the XZ plane, specifically for the case where the acceleration direction is the third direction DR3 and the case where the acceleration direction is the fourth direction DR4. The initial state refers to the state where the third direction DR3 does not produce acceleration, including gravitational acceleration.

[0049] First, in the initial state, when the detection units ZA and ZB are viewed from the side in the second direction DR2, the ends of the movable electrodes 21 and 22 and the fixed electrodes 11 and 12 on the fourth direction DR4 side are aligned. As described above, since the movable electrode 21 of the movable electrode unit 20 has a first recess R1 and the fixed electrode 12 of the fixed electrode unit 10 has a second recess R2, as shown in the initial state, when viewed from the side in the second direction DR2, the ends of the fixed electrodes 11 and 12 and the movable electrodes 21 and 22 on the third direction DR3 side are misaligned.

[0050] Next, under the condition of acceleration in the third direction DR3, the movable electrode 21 of the detection unit ZA and the movable electrode 22 of the detection unit ZB are respectively subjected to the inertial force accompanying the acceleration and displaced towards the fourth direction DR4. At this time, in the detection unit ZA, the opposing area of ​​the fixed electrode 11 and the movable electrode 21 in the first direction DR1 decreases due to the displacement of the movable electrode 21 towards the fourth direction DR4. On the other hand, in the detection unit ZB, since no recess is provided on the movable electrode 22, the opposing area of ​​the fixed electrode 12 and the movable electrode 22 in the first direction DR1 remains constant even if the movable electrode 22 is displaced towards the fourth direction DR4. Thus, when acceleration occurs in the third direction DR3, the opposing area decreases in the detection unit ZA, while the opposing area remains unchanged in the detection unit ZB.

[0051] Furthermore, when acceleration occurs in the fourth direction DR4, the movable electrode 21 of the detection unit ZA and the movable electrode 22 of the detection unit ZB are respectively subjected to inertial forces accompanying the acceleration, causing them to displace towards the third direction DR3. At this time, in the detection unit ZA, the opposing area of ​​the fixed electrode 11 and the movable electrode 21 in the first direction DR1 remains constant because the first recess R1 is provided on the movable electrode 21. On the other hand, in the detection unit ZB, the opposing area of ​​the fixed electrode 12 and the movable electrode 22 in the first direction DR1 decreases due to the displacement of the movable electrode 22 towards the fourth direction DR4. Thus, when acceleration occurs in the fourth direction DR4, the opposing area remains constant in the detection unit ZA, while the opposing area decreases in the detection unit ZB.

[0052] Thus, when acceleration in the third direction DR3 is generated, the opposing area of ​​the fixed electrode 11 and the movable electrode 21 on the detection unit ZA decreases; when acceleration in the fourth direction DR4 is generated, the opposing area of ​​the fixed electrode 12 and the movable electrode 22 on the detection unit ZB decreases. Therefore, by detecting the decrease in the opposing area on the detection units ZA and ZB as a change in the electrostatic capacitance between the fixed electrode 14 and the movable electrode 24, accelerations in the third direction DR3 and the fourth direction DR4 can be detected.

[0053] The fixed electrode 11 of the first fixed electrode group 10A and the movable electrode 21 of the first movable electrode group 20A are arranged opposite each other, forming a parallel plate-type capacitor in the detection section ZA. Similarly, the fixed electrode 12 of the second fixed electrode group 10B and the movable electrode 22 of the second movable electrode group 20B are arranged opposite each other, forming a parallel plate-type electrostatic capacitor in the detection section ZB. Moreover, for example, it is possible to detect changes in electrostatic capacitance in the detection section ZA as the N-side and changes in electrostatic capacitance in the detection section ZB as the P-side.

[0054] like Figure 4 When the acceleration direction is the third direction DR3, as shown in the case where the physical quantity sensor 1 generates the third direction DR3 acceleration, the movable electrode 24 is displaced towards the fourth direction DR4 due to inertial force. At this time, the opposing area of ​​the fixed electrode 12 and the movable electrode 22 on the P side of the detection unit ZB remains unchanged, so the electrostatic capacitance does not change. On the other hand, the opposing area of ​​the fixed electrode 11 and the movable electrode 21 on the N side of the detection unit ZA decreases. Therefore, the difference in electrostatic capacitance between the P side and the N side can be detected by using a differential amplifier circuit QV (not shown), and the detection signal of the third direction DR3 acceleration can be obtained. In the case of generating the fourth direction DR4 acceleration, conversely, the opposing area of ​​the fixed electrode 12 and the movable electrode 22 on the P side of the detection unit ZB decreases, and the electrostatic capacitance decreases; on the other hand, the opposing area of ​​the fixed electrode 11 and the movable electrode 21 on the N side of the detection unit ZA does not change, and the electrostatic capacitance does not change. Therefore, by using the differential amplifier circuit QV for detection, a detection signal of the acceleration in the fourth direction DR4 can be obtained. The detection of electrostatic capacitance can be achieved, for example, by connecting the first fixed electrode group 10A to the differential amplifier circuit QV (not shown) via wiring LFA and pad PFA (not shown), connecting the second fixed electrode group 10B to the differential amplifier circuit QV (not shown) via wiring LFB and pad PFB (not shown), and connecting the movable body MB to the differential amplifier circuit QV (not shown) via wiring LV and pad PV (not shown).

[0055] In the above description, it was explained that by providing a first recess R1 on the movable electrode 21 of the detection unit ZA and a second recess R2 on the fixed electrode 12 of the detection unit ZB, the accelerations in the third direction DR3 and the fourth direction DR4 can be detected. However, the physical quantity sensor 1 of this embodiment is not limited to this structure. For example, by providing a first recess R1 on the fixed electrode 11 of the detection unit ZA, the acceleration in the fourth direction DR4 can be detected by the detection unit ZA, and by providing a second recess R2 on the movable electrode 22 of the detection unit ZB, the acceleration in the third direction DR3 can be detected by the detection unit ZB.

[0056] As described above, in this embodiment, by providing a first recess R1 in the first movable electrode group 20A and a second recess R2 in the second fixed electrode group 10B, the accelerations in the third direction DR3 and the fourth direction DR4 can be detected. Here, considering the movement of the movable body MB about the first direction DR1 as its rotation axis, the question arises as to whether the first recess R1 provided in the first movable electrode group 20A of the movable body MB affects the movement of the movable body MB. That is, if the weight reduction on the N side of the frame portion 30 is proportional to the volume of the first recess R1, the center of gravity balance of the movable body MB will be poor, which may cause adverse effects on the movement of the movable body MB.

[0057] First, considering the moment of inertia I of the movable body MB about the X-axis, since the moment of inertia I is the product of the square of the distance from the rotation axis and the mass, the moment of inertia I becomes uniform along the X-axis without the first recess R1 and the third recess R3. However, by providing the first recess R1 in the first movable electrode group 20A, the moment of inertia I becomes non-uniform along the X-axis. Specifically, in the region on the X-axis where the first movable electrode group 20A is provided, the moment of inertia I decreases because the mass is reduced by the first recess R1, but in the region where the second movable electrode group 20B is provided, the moment of inertia I remains unchanged because no recess is provided. Thus, the moment of inertia I of the movable body MB becomes non-uniform along the X-axis.

[0058] Next, regarding Figure 1 The cross section AA′ of the physical quantity sensor 1 in the middle is used Figure 5 An explanation will be given for the case where the third recess R3 is not provided in the frame portion 30. Figure 5 This represents a weightless state where there is no gravitational acceleration in the Z direction. In this state, the line segment connecting the center O of the connecting frame 30 to the first movable electrode group 20A intersects the X-axis at an angle α, and the line segment connecting the center O of the connecting frame 30 to the second movable electrode group 20B intersects the X-axis at an angle β. Since the first movable electrode group 20A has a first recess R1, the angle α has a certain value. However, since the second movable electrode group 20B does not have a recess, its center of gravity is located on the X-axis, and the angle β is 0. Figure 6The cross section AA′ of sensor 1 represents the physical quantity of gravitational acceleration in the Z direction. As described above, due to the non-uniformity of the inertial torque I along the X-axis, the displacement in the rotational motion about the X-axis differs between the regions of the first movable electrode group 20A and the second movable electrode group 20B. Therefore, the gravity F1 experienced by the first movable electrode group 20A and the gravity F2 experienced by the second movable electrode group 20B, which are accompanied by acceleration, are also different. In this case, since the second movable electrode group 20B has a larger mass, the gravity F2 is greater than the gravity F1. Here, the support beams 42 and 43 connecting the movable body MB and the fixed part 40 function as springs with restoring force, and are thus balanced by a certain elastic deformation. Therefore, the upper and lower surfaces of the movable body MB are affected by different magnitudes of gravity F1 and F2. Figure 6 As shown, it is balanced by tilting only an angle θ in the X-axis direction. Therefore, physical quantity sensor 1 is from Figure 4 The ideal rotational motion shown produces several deviations. This particularly affects the linearity of the acceleration sensitivity. However, it is possible to correct for these deviations in the linearity of the sensitivity. Furthermore, Figure 6 And the following Figure 7 To visualize the effect of the mass non-uniformity of the movable body MB, the offset of the aforementioned rotation axis is represented more significantly.

[0059] Moreover, for those who are affected Figure 6 The study investigates the case where a movable body MB, which is subject to gravitational acceleration, is subjected to a force in a direction other than the Z direction, such as the X direction, and thus experiences acceleration. The movable body MB is connected to the other end of a support beam 42, 43, which is fixed at one end to a fixed part 40. It can basically only move in the Z direction, so even if it is subjected to a force in the X direction, it will not affect the detection of acceleration in the Z-axis direction.

[0060] However, as Figure 5 , Figure 6 As explained, when the second part 32 of the frame 30 is tilted from the X-axis due to gravitational acceleration, it is necessary to consider the relationship between the position of each part of the movable body MB from the center O of the frame 30 and the inertial force experienced by each part of the movable body MB with acceleration. Specifically, the torque is calculated by taking the outer product of the position vector of each part of the movable body MB starting from the center O of the frame 30 and the inertial force vector experienced by each part of the movable body MB with acceleration in the X direction. Figure 7Let the inertial force applied to the portion of the first movable electrode group 20A and the portion of the second movable electrode group 20B of this physical quantity sensor 1 under the state of generating acceleration in the first direction DR1 be represented by a vector. The inertial force F3 applied to the portion of the first movable electrode group 20A provided with the first recess R1 is a vector in the -X direction, and the inertial force F4 applied to the portion of the second movable electrode group 20B without the recess is also a vector in the -X direction. Therefore, for the first movable electrode group 20A, the vector of the inertial force F3 in the -X direction is related to the position vector r from the center O. 20A The outer product of r 20A F3sinθ represents this. On the other hand, for the second movable electrode group 20B, the vector of the inertial force F4 in the -X direction and the position vector r from the center O are... 20B The outer product of r 20B F4sin(π+θ) represents this. However, at this point, the angle θ between the upper and lower ends of the movable body MB and the X-axis is much larger than... Figure 5 Let θ be the angle α and β. That is, let θ >> α and β. Since the distance from the center O to each movable electrode group is equal, if we let r 20A =r 20B =r, then the torque experienced by the movable body MB around the fixed part 40 is expressed as r(F3-F4)sinθ. Here, in the first movable electrode group 20A with the first recess R1 and the second movable electrode group 20B without the recess, the mass of the second movable electrode group 20B is larger. Therefore, the inertial force F4 experienced by the second movable electrode group 20B is greater than the inertial force F3 experienced by the first movable electrode group 20A, and the torque r(F3-F4)sinθ becomes a negative value. Therefore, a torque r(F3-F4)sinθ with the Y-axis as the rotation axis is applied to the movable body MB. Therefore, in addition to the acceleration in the Z direction with the X-axis as the rotation axis originally predetermined by the physical quantity sensor 1, a rotational motion component with the Y-axis as the rotation axis is also generated.

[0061] Thus, when the inertial torque I of the movable body MB is non-uniform along the X-axis, combined with the elasticity of the supporting beams 42 and 43, the physical quantity sensor 1 causes unwanted rotational motion, potentially increasing the sensitivity of the other axis. This phenomenon becomes particularly pronounced when subjected to gravitational acceleration in the Z-direction. Furthermore, the so-called sensitivity of the other axis refers to the sensitivity when the physical quantity sensor detects a physical quantity other than the direction of the object being detected as a physical quantity in the direction of the object being detected.

[0062] The physical quantity sensor disclosed in Patent Document 1 includes a rotor corresponding to a movable body MB and multiple stators corresponding to fixed electrode sections 10. At least a portion of the rotor and multiple stators have localized indentations in thickness along the Z-direction. This results in non-uniformity of the inertial torque I corresponding to the rotation axis of the rotor, and as described above, the sensitivity of the other axis may increase. Thus, in a physical quantity sensor that detects acceleration in the Z-direction, if the thicknesses of the fixed electrode 14 and the movable electrode 24 on the third direction DR3 are set to different thicknesses, non-uniformity of the inertial torque I of the movable body MB, including the movable electrode section 20, occurs, increasing the sensitivity of the other axis and degrading the detection accuracy of the physical quantity sensor.

[0063] Regarding this, according to this embodiment, as described above, a third recess R3 is provided in the second portion 32 of the frame portion 30 of the movable body MB. Furthermore, the third recess R3 is provided on the first direction DR1 side of the second portion 32 of the frame portion 30. In the physical quantity sensor 1, since the first recess R1 is provided on the opposite side of the first direction DR1 of the second portion 32 of the frame portion 30, the inertial torque I of the movable body MB is non-uniform along the first direction DR1. Therefore, by providing the third recess R3 in the region of the second portion 32 where the second movable electrode group 20B is provided, opposite to the location where the first recess R1 is provided on the X-axis, this non-uniformity of the inertial torque I of the movable body MB can be eliminated. That is, by providing the third recess R3, the mass non-uniformity in the first direction DR1 of the second portion of the frame portion 30 can be eliminated. Therefore, the offset of rotational motion caused by the acceleration of the third direction DR3 of the physical quantity sensor 1 can be corrected. Furthermore, the shape of the third recess R3 can be appropriately designed. For example, the shape of the third recess R3 when viewed from above can be rectangular or circular. Alternatively, it can be discretely arranged as described in the first detailed example below.

[0064] As described above, the physical quantity sensor 1 of this embodiment includes: a fixing part 40 fixed to a substrate 2; a fixing electrode part 10 disposed on the substrate 2 and provided with a first fixed electrode group 10A and a second fixed electrode group 10B; support beams 42 and 43 connected at one end to the fixing part 40; and a movable body MB. The movable body MB has: a movable electrode part 20 provided with a first movable electrode group 20A and a second movable electrode group 20B; and a frame part 30 connecting the movable electrode part 20 and the other end of the support beams 42 and 43. The movable electrode part 20 includes a first movable electrode group 20A and a second movable electrode group 20B, wherein each movable electrode 21 of the first movable electrode group 20A faces each fixed electrode 11 of the first fixed electrode group 10A, and each movable electrode 22 of the second fixed electrode group 10B faces each fixed electrode 12. The first movable electrode group 20A is provided with a first recess R1 that is recessed into the third direction DR3, the second fixed electrode group 10B is provided with a second recess R2 that is recessed into the third direction DR3, and the area on the side of the second movable electrode group 20B of the frame portion 30 is provided with a third recess R3 that is recessed into the third direction DR3.

[0065] In this way, since the first recess R1 and the third recess R3 have the same area and the same depth, the non-uniformity of the mass of the movable body MB of the physical quantity sensor 1 on the axis of the first direction DR1 can be eliminated. Therefore, the center of gravity of the physical quantity sensor in the third direction DR3 will not shift. Therefore, displacement can be suppressed when physical quantities other than those in the third direction DR3, such as acceleration, are applied. Therefore, the sensitivity of the other axis of the physical quantity sensor 1 can be reduced, thereby improving the detection accuracy of the physical quantity. In addition, a good physical quantity sensor that is not easily affected by unwanted vibrations or impacts from the outside and has high long-term reliability can be provided.

[0066] Furthermore, in this embodiment, the first recess R1 and the third recess R3 have the same area when viewed from above in the third direction DR3. By making the depths of the first recess R1 and the third recess R3 the same, the non-uniformity of the inertial torque I along the first direction DR1 with the first direction DR1 as the rotation axis can be eliminated, thereby improving the detection accuracy of the physical quantity sensor 1.

[0067] As will be discussed later. Figure 20 , Figure 21As explained, the first recess R1 of the first movable electrode group 20A and the third recess R3 of the frame portion 30 can be provided by etching the same silicon deposited layer. Therefore, as long as the design ensures that the areas of the first recess R1 and the third recess R3 are the same when viewed from above in the third direction DR3, the silicon layer can be processed to the same depth in both the first recess R1 and the third recess R3 through a common etching process, making the volumes of the first recess R1 and the third recess R3 equal. Alternatively, the first recess R1 and the third recess R3 can be etched separately to the same depth. This eliminates the non-uniformity of the mass of the movable body MB of the physical quantity sensor 1 on the axis of the first direction DR1. Furthermore, the dimensions in the semiconductor manufacturing process deviate by approximately ±10% to ±20% due to process variations, so the aforementioned same area includes cases where the areas are approximately the same. In addition, when the third recess R3 is divided, this area refers to the sum of the areas of the third recess R3 when viewed from above in the third direction DR3. Thus, "same" in this embodiment includes approximately the same. For example, in this embodiment, the same area, the same volume, and the same length can be considered as the same design value, or they can be approximately the same within the error range caused by variations in the manufacturing process or tolerances.

[0068] Furthermore, in this embodiment, the first recess R1 and the third recess R3 can have the same depth in the third direction DR3. This ensures that the areas of the first recess R1 and the third recess R3 are the same when viewed from above in the third direction DR3, making their volumes equal. Therefore, the non-uniformity of the inertial torque I in the first direction DR1 when rotating about the first direction DR1 can be eliminated, improving the detection accuracy of the physical quantity sensor 1.

[0069] As described above, when viewed from above by a third party (DR3), if the areas and depths of the first recess R1 and the third recess R3 are the same, then the volumes of the first recess R1 and the third recess R3 are also the same. Furthermore, both the first recess R1 and the third recess R3 are provided for processing the silicon deposit layer; therefore, the mass of the portion lost due to processing in each of the first recess R1 and the third recess R3 is equal. Thus, the volumetric inhomogeneity of the movable body MB along the X-axis is eliminated, achieving the aforementioned effect. Moreover, the depths of the first recess R1, the second recess R2, and the third recess R3 mentioned above refer to the depths described later. Figure 20 The depth of processing begins from the outermost layer of the wafer 208.

[0070] Furthermore, in this embodiment, the first recess R1 and the third recess R3 can have the same volume. This eliminates the non-uniformity of the first direction DR1 of the inertial torque I when rotating about the first direction DR1 as the axis of rotation, thereby improving the detection accuracy of the physical quantity sensor 1. Here, volume refers to the volume of the portion of the original silicon deposited layer when the first recess R1 and the third recess R3 are formed by etching or other processes.

[0071] 2. Detailed structural example

[0072] Figure 8 This is a top view of the first detailed example of this embodiment. The structure of the third recess R3 is similar to... Figure 1 The structural examples shown are different. Specifically, in the first detailed example, the third recess R3 is divided into four segmented recesses when viewed from above in the third direction DR3. Moreover, each segmented recess is a rectangular shape with the second direction DR2 as its length when viewed from above in the third direction.

[0073] As described above, the physical quantity sensor 1 of this embodiment achieves improved detection accuracy of the physical quantity in the third direction DR3 by making the volumes of the first recess R1 and the third recess R3 equal, thereby uniformly distributing the inertial torque I of the movable body MB along the first direction DR1. Therefore, for example, if the areas of the first recess R1 and the third recess R3 are designed to be equal when viewed from above on the third direction DR3, it is possible to make the volumes of the first recess R1 and the third recess R3 equal if they are manufactured in a manner that makes the depths of the first recess R1 and the third recess R3 equal.

[0074] Here, when the opening patterns of the first recess R1 and the third recess R3 are different when viewed from above in the third direction DR3, it is known that even under the same etching conditions, the etching rate of each recess will differ due to a micro-load effect. Furthermore, even if the first recess R1 and the third recess R3 have the same opening pattern when viewed from above, differences in the surrounding exposure pattern and differences in position within the wafer or chip will affect the etching rate of each recess. Therefore, if the area of ​​the first recess R1 when viewed from above is simply made the same as the total area of ​​the segmented recesses of the third recess R3, and etching is performed under the same conditions such as time and gas atmosphere, the volumes of each recess will not be equal.

[0075] If we study from this perspective Figure 1In the physical quantity sensor 1 shown, the third recess R3 is an undivided recess, forming a rectangular shape with a relatively wide opening when viewed from above in the third direction DR3. On the other hand, the first recess R1, originally part of a fine pattern of the movable electrode 21 of the first movable electrode group 20A, is now a rectangular shape with multiple patterns arranged along the length direction DR2 when viewed from above. Furthermore, it is envisioned that the third recess R3 is processed from a portion of a silicon deposited layer, while the area surrounding the first recess R1 is generally a material other than the silicon deposited layer. Thus, the processed patterns or the surrounding material of the recesses are different in the first recess R1 and the third recess R3. Therefore, even if the first recess R1 and the third recess R3 are processed at the same time and under the same etching conditions, the depth of each recess is different. In this case, even if the areas of the first recess R1 and the third recess R3 are designed to be equal when viewed from above, the volumes of each recess are different. On the other hand, in the physical quantity sensor 1 of this embodiment, it is envisioned that photolithography is used to perform etching simultaneously, so that the first recess R1, the second recess R2, and the third recess R3 all have the same depth. Therefore, in Figure 1 In the structural example shown where the third recess R3 is not divided, when the first recess R1 and the third recess R3 are processed together, the non-uniformity of the moment of inertia I of the movable body MB along the first direction DR1 cannot be eliminated. Therefore, the improvement in the detection accuracy of physical quantities cannot be fully realized.

[0076] Regarding this, according to the first detailed example, the third recess R3 is divided into four segmented recesses. Therefore, by adjusting the pattern of the third recess R3 when viewed from above, it is possible to optimize the etching rate of the first recess R1 and the third recess R3 to be close, and to process each recess to the same depth under the same etching conditions by processing them together. Specifically, when the etching rate of the third recess R3 is slower than that of the first recess R1, for example, when viewed from above in the third direction DR3, if the aspect ratio of the third recess R3 is reduced by increasing the width of each segmented recess in the first direction, the etching rate can be accelerated. Furthermore, it is believed that the etching rate can be adjusted even by adjusting the spacing of each segmented recess of the third recess R3. In addition, in the first detailed example, the third recess R3 is divided into four, but the number of segments can be increased or decreased.

[0077] As described above, according to this embodiment, the third recess R3 can be divided into multiple segmented recesses. Thus, by adjusting the pattern of the third recess R3, the etching rates of the first recess R1 and the third recess R3 can be adjusted to be similar. Therefore, the first recess R1 and the third recess R3 can be machined to the same depth by processing them together. Therefore, the non-uniformity of the inertial moment I in the first direction DR1 of the movable body MB can be eliminated with a simpler process, improving the detection accuracy of physical quantities. Furthermore, regarding the depth of each segmented recess, if it is machined to the point where the second portion 32 of the frame portion 30 is penetrated, the rigidity of the frame portion 30 may deteriorate. In addition, in this case, the frame portion 30 itself is prone to torsion, which can also cause adverse effects when subjected to high-frequency vibrations.

[0078] Furthermore, in the first detailed example, the width of the dividing recess in the first direction DR1 can be the same as the width of each movable electrode 21 of the first movable electrode group 20A in the first direction DR1. Thus, for example, in... Figure 8 If the first recess R1 is composed of 4 rectangular shapes, and 4 dividing recesses of the same width are provided in the third recess, the non-uniformity of mass of the movable body MB in the first direction DR1 can be eliminated.

[0079] Furthermore, in the first detailed example, the total area of ​​the multiple segmented recesses can be the same as the area of ​​the first recess R1 when viewed from above in the third direction DR3. As described above, according to the first detailed example, by changing the pattern of the third recess when viewed from above in the third direction DR3, the etching rate of the third recess can be adjusted, thereby making the etching rates of the first recess R1 and the third recess R3 similar. Therefore, when viewed from above in the third direction DR3, if the total area of ​​the multiple segmented recesses of the third recess R3 is the same as the area of ​​the first recess R1, then if the recesses are subsequently processed with equal depths, the volumes of the recesses will be equal. Therefore, by performing a combined etching process, it is possible to process the first recess R1 to have the same volume as the third recess R3. Therefore, it is possible to achieve the effect of improving the detection sensitivity of the physical quantity sensor 1 with a simpler and lower-cost manufacturing process.

[0080] Furthermore, in this embodiment, the length of the first recess R1 in the second direction DR2 can be the same as the length of each movable electrode 21 of the first movable electrode group 20A in the second direction DR2. For example, in Figure 8 In the first detailed example shown, the area of ​​the first recess R1 with the added diagonal lines can also be made to cover the entire comb-shaped movable electrode 21.

[0081] As described above, the physical quantity sensor 1 of this embodiment detects the change in the opposing area of ​​the fixed electrode 14 and the movable electrode 24 as a change in electrostatic capacitance, and thus detects a physical quantity. Therefore, by providing a wider area for the first recess R1 as in this embodiment, a wider opposing area of ​​the fixed electrode 11 and the movable electrode 21 can be ensured. Therefore, acceleration can be detected as a larger change in electrostatic capacitance, and the detection sensitivity of the physical quantity sensor 1 can be improved. Furthermore, the above can also be applied to the detection unit ZB. For example, it is also possible to make... Figure 8 The area of ​​the second recess R2 with the added diagonal line covers the entire fixed electrode 12. In this way, the opposing area of ​​the fixed electrode 12 and the movable electrode 22 can be ensured more widely in the detection unit ZB, and the acceleration can be detected as a larger change in electrostatic capacitance.

[0082] Figure 9 This is a top view of the second detailed example of this embodiment. The structure of the first detection element 100 is similar to... Figure 1 Structural examples Figure 8 The first detailed example differs from the second detailed example. Specifically, in the second detailed example, the first detection element 100 includes a first element section 91 and a second element section 92. The first element section 91 and the second element section 92 use the fixing section 40 as a common fixing device. The first element section 91 is provided on the side of the second direction DR2, and the second element section 92 is provided on the side opposite to the second direction DR2. Moreover, each element section is provided with detection sections ZA and ZB corresponding to the N side and the P side, respectively, which are capable of detecting physical quantities in the third direction DR3.

[0083] The first component section 91 is for... Figure 1 The structure is the same as that of the first detection element 100 in the first detailed example. The second element part 92 includes a fixed electrode part 50 having a first fixed electrode group 50A and a second fixed electrode group 50B, a second movable body MB2, and support beams 82 and 83. Here, in order to distinguish the movable body of the first element part 91 from the movable body of the second element part 92, the movable body of the first element part 91 is described as the first movable body MB1. The second movable body MB2 includes: a movable electrode part 60 having a first movable electrode group 60A and a second movable electrode group 60B; and a frame part 70.

[0084] The fixed electrode section 50, the first fixed electrode group 50A, and the second fixed electrode group 50B of the second element section 92 correspond to the fixed electrode section 10, the first fixed electrode group 10A, and the second fixed electrode group 10B of the first element section 91. Furthermore, the fixed electrode section 10 includes a second fixed electrode group 10B corresponding to the P side and a first fixed electrode group 10A corresponding to the N side, each electrode group having fixed electrodes 12 and 11 respectively. Similarly, the fixed electrode section 50 includes a second fixed electrode group 50B corresponding to the P side and a first fixed electrode group 50A corresponding to the N side, each electrode group having fixed electrodes 52 and 51 respectively.

[0085] Furthermore, the movable electrode section 60, the first movable electrode group 60A, and the second movable electrode group 60B of the second element section 92 correspond to the movable electrode section 20, the first movable electrode group 20A, and the second movable electrode group 20B of the first element section 91. Moreover, in the movable electrode section 20, a second movable electrode group 20B corresponding to the P side and a first movable electrode group 20A corresponding to the N side are provided, each electrode group having movable electrodes 22 and 21 respectively. Similarly, in the movable electrode section 60, a second movable electrode group 60B corresponding to the P side and a first movable electrode group 60A corresponding to the N side are provided, each electrode group having movable electrodes 62 and 61 respectively. Movable electrodes 21 and 22 extend from the second portion 32 of the frame section 30 and are arranged opposite to fixed electrodes 11 and 12. Furthermore, movable electrodes 61 and 62 extend from the second portion 72 of the frame section 70 and are arranged opposite to fixed electrodes 51 and 52. Moreover, with… Figure 1 , Figure 8 Similarly, in the illustrated structural example, each electrode is connected to a differential amplifier circuit QV (not shown). The support beams 82 and 83 of the second element section 92 correspond to the support beams 42 and 43 of the first element section 91, and the frame section 70 of the second element section 92 corresponds to the frame section 30 of the first element section 91. With this structure, the second detailed example can detect the acceleration of the third-direction DR3 by the first element section 91 and the second element section 92 respectively.

[0086] Furthermore, a first recess R4 is provided in the first movable electrode group 60A of the second element section 92, a second recess R5 is provided in the second fixed electrode group 50B, and a third recess R6 is provided in the second part 72 of the frame section 70. Moreover, the first recess R4, the second recess R5, and the third recess R6 of the second element section 92 correspond to the first recess R1, the second recess R2, and the third recess R3 of the first element section 91, respectively.

[0087] Thus, by providing first recesses R4 and third recesses R6 in the second element section 92, corresponding to the first recesses R1 and R3 in the first element section 91, the mass inhomogeneity of the second movable body MB2 can be eliminated. Therefore, the sensitivity of the other axis can be reduced in each element section, achieving high-precision detection of physical quantities, and the detection sensitivity can be improved by providing two element sections. In addition, unwanted vibrations caused by external vibrations or impacts can be avoided, providing a high-quality physical quantity sensor 1 with high long-term reliability.

[0088] Figure 10 This is a top view of a modified example of the second detailed example of this embodiment. The pattern of the third recess when viewed from above differs from that in the second detailed example. Specifically, the pattern of the third recess R3 in the second detailed example is, in this modified example, a plurality of segmented recesses in a rectangular shape with the first direction DR1 as the length direction. Even if the third recess R3 is provided as in this embodiment, the effects of providing the aforementioned plurality of segmented recesses can be obtained.

[0089] In addition, in this embodiment, the movable body MB may include: a first part 31, one end of which is connected to the other end of the support beams 42 and 43, and extends in the second direction as the long side direction; and a second part 32, which is connected to one end of the first part 31 and extends in the first direction DR1 as the long side direction.

[0090] Thus, in Figure 1 The physical quantity sensor 1 shown above can form a movable body MB in a roughly U-shape. Moreover, as described above, the movable body MB can rotate about the first direction DR1 via the support beams 42 and 43, and the physical quantity sensor 1 can detect the acceleration of the third direction DR3.

[0091] In addition, in this embodiment, the movable electrode part 20 is connected to the second part 32.

[0092] In this way, the movable electrode part 20 can move as an integral part with the second part 32 of the frame part 30. Therefore, by the movement of the movable body MB about the first direction DR1 as the rotation axis, the physical quantity sensor 1 can detect the acceleration of the third direction DR3.

[0093] Furthermore, in this embodiment, the third recess R3 is provided in the second portion 32. This reduces the volume of a portion of the second portion 32 of the frame portion 30. Therefore, the non-uniformity of the mass of the movable body MB along the first direction DR1 caused by the provision of the first recess R1 can be eliminated, and the detection accuracy of the physical quantity sensor 1 can be improved.

[0094] 3. Inertial Measurement Device

[0095] Next, use Figure 11 , Figure 12 An example of the inertial measurement device 2000 of this embodiment will be described. Figure 11 The inertial measurement unit (IMU) 2000 shown is a device for detecting the inertial motion of moving objects such as cars and robots, including their posture and movements. The IMU 2000 is a so-called 6-axis motion sensor, equipped with accelerometers that detect accelerations along three axes (ax, ay, az) and angular velocity sensors that detect angular velocities around three axes (ωx, ωy, ωz).

[0096] The inertial measurement unit 2000 is a cuboid with a roughly square planar shape. Furthermore, threaded holes 2110, serving as mounting parts, are formed near the vertices at two points along the diagonal of the square. Two screws pass through these threaded holes 2110, allowing the inertial measurement unit 2000 to be fixed to the mounting surface of a vehicle or similar object. Moreover, by selecting components or changing the design, it can be miniaturized to a size suitable for mounting smartphones or digital cameras.

[0097] The inertial measurement device 2000 includes a housing 2100, a connecting member 2200, and a sensor module 2300, wherein the sensor module 2300 is inserted into the housing 2100 through the connecting member 2200. The sensor module 2300 includes an inner housing 2310 and a circuit board 2320. The inner housing 2310 has a recess 2311 for preventing contact with the circuit board 2320 and an opening 2312 for exposing the connector 2330 (described later). Furthermore, the circuit board 2320 is bonded to the lower surface of the inner housing 2310 via an adhesive.

[0098] like Figure 12 As shown, a connector 2330, an angular velocity sensor 2340z for detecting angular velocity about the Z-axis, and an acceleration sensor unit 2350 for detecting acceleration in each of the X, Y, and Z-axis directions are mounted on the upper surface of the circuit board 2320. Additionally, an angular velocity sensor 2340x for detecting angular velocity about the X-axis and an angular velocity sensor 2340y for detecting angular velocity about the Y-axis are mounted on the side of the circuit board 2320.

[0099] The acceleration sensor unit 2350 includes at least a physical quantity sensor 1 for measuring the aforementioned acceleration in the Z-axis direction. Depending on the requirements, it can detect acceleration in a single-axis direction, or acceleration in a dual-axis or tri-axis direction. Furthermore, the angular velocity sensors 2340x, 2340y, and 2340z are not particularly limited; for example, a vibrating gyroscope sensor utilizing the Coriolis force can be used.

[0100] Additionally, a control IC 2360 is mounted on the lower surface of the circuit board 2320. The control IC 2360, which controls the device based on the detection signal output from the physical quantity sensor 1, is, for example, a microcontroller unit (MCU), which includes a storage unit containing non-volatile memory, an A / D converter, etc., and controls various parts of the inertial measurement device 2000. Furthermore, several other electronic components are also mounted on the circuit board 2320.

[0101] As described above, the inertial measurement device 2000 of this embodiment includes a physical quantity sensor 1 and a control IC 2360, which is a control unit that performs control based on the detection signal output from the physical quantity sensor 1. According to this inertial measurement device 2000, since an acceleration sensor unit 2350 including the physical quantity sensor 1 is used, an inertial measurement device 2000 that can enjoy the effects of the physical quantity sensor 1 and achieve high precision can be provided.

[0102] Furthermore, the inertial measurement device 2000 is not limited to... Figure 11 , Figure 12 The structure is as follows. For example, the inertial measurement device 2000 can be configured such that angular velocity sensors 2340x, 2340y, and 2340z are not provided, and only physical quantity sensor 1 is provided as an inertial sensor. In this case, for example, the inertial measurement device 2000 can be implemented by housing physical quantity sensor 1 and control IC 2360, which implements the control unit, in a package that serves as a housing container.

[0103] 4. Manufacturing method

[0104] Finally, the manufacturing method of this embodiment will be described. Figure 13 yes Figure 1 The image shows a top view of the physical quantity sensor 1 according to this embodiment. Hereinafter, in... Figures 14-21 In the section on the manufacturing method of this embodiment, a link is used. Figure 13 The section view shown is illustrated on the dashed line between points B and B′ in the top view.

[0105] First, such as Figure 14As shown, a silicon substrate 200 is prepared, and a surface oxide film 204 of approximately 1 μm is formed, which is then patterned using photolithography. After partially removing the surface oxide film 204 using wet etching with BHF (Buffered Hydrogen Fluoride), etching is performed on the silicon substrate 200 to a depth of approximately 20–50 μm. This etching can be wet etching using KOH or TMAH, or dry etching using SF6 gas. Alternatively, it can be silicon deep etching based on the BOSCH process using alternating SF6 and C4F8. This forms a cavity 202. The unwanted surface oxide film 204 can be removed or left behind.

[0106] Next, as Figure 15 As shown, a silicon substrate 200 is bonded to a silicon substrate wafer 208, which forms a structural layer. During bonding, an embedded insulating film 206 is formed on the silicon substrate, activated by plasmas such as Ar and N2, and then subjected to water washing before bonding. Additionally, after bonding, an annealing treatment at 500–1100°C can be performed to enhance strength. During this process, the embedded insulating film 206 can remain at the bottom of the cavity 202. After bonding, the wafer 208 is ground to form a structural layer with a thickness of approximately 20–30 μm. Furthermore, the grinding of the wafer 208 can utilize processes such as CMP (Chemical Mechanical Polishing). Moreover, as... Figure 16 As shown, a SiO2 layer 210 is formed on the structure layer to serve as a hard mask. The SiO2 layer 210 can be formed by thermal oxidation, CVD (Chemical Vapor Deposition) film formation, SOG (Spin On-Glass) film formation, etc. In particular, the thermally oxidized SiO2 layer 210 is preferred because it exhibits a high selectivity during silicon etching. In this manufacturing method, a thermally oxidized film of approximately 1 μm is used.

[0107] Next, as Figure 17 As shown, patterning is performed using photolithography, and the thickness of the SiO2 layer 210 where the first recess R1 is formed is thinned by wet etching or the like. Here, if the hard mask on the SiO2 layer 210 is a thermal oxide film, wet etching using BHF or the like is preferable. Furthermore, as... Figure 18 As shown, a photoresist film 214 is used to pattern the shape of each element of the physical quantity sensor 1. Furthermore, a SiO2 layer 210 is processed by dry etching or the like. In addition, CHF3 gas can be used, for example, in the dry etching process.

[0108] Next, as Figure 19As shown, the unwanted photoresist 214 is removed by ashing or similar methods, for example using the BOSCH process, and the wafer 208, which forms the structural layer, is etched. Here, the depth of the etching process extends from the outermost layer of the buried insulating film 206 to only h1. Then, as... Figure 20 As shown, the SiO2 layer 210, which is deposited as a hard mask, is etched across its entire surface to expose the silicon structure layer in the region where the first recess R1 is located. Furthermore, this etching method can be either dry etching or wet etching. Moreover, as... Figure 21 As shown, if the entire silicon structure layer is etched, the first recess R1 becomes a step of depth h1, and the gas portion is processed to the bottom, becoming a through-hole. Finally, as... Figure 22 As shown, remove the unnecessary hard mask.

[0109] Furthermore, the regions where the second recess R2 and the third recess R3 are formed are also similar to the first recess R1, with a third recess DR3 formed in a portion of the structure layer. Therefore, by patterning the regions where the second recess R2 and the third recess R3 are formed on the SiO2 layer 210 of the hard mask, and etching the wafer 208, which becomes the structure layer, the second recess R2 and the third recess R3 can be formed.

[0110] As described above, the manufacturing method of this embodiment is a method for manufacturing a physical quantity sensor 1 that detects physical quantities on the third direction DR3 when three mutually orthogonal directions are designated as the first direction DR1, the second direction DR2, and the third direction DR3. This method includes a fixed electrode part forming process for forming a fixed electrode part 10 on a substrate 2, and a movable body forming process for forming a movable body MB. Furthermore, the physical quantity sensor 1 includes a fixed part 40 fixed to the substrate 2, one end of support beams 42 and 43 connected to the fixed part 40, the fixed electrode part 10 disposed on the substrate 2, and includes a first fixed electrode group 10A and a second fixed electrode group 10B. Moreover, the movable body MB includes: a movable electrode part 20, a first movable electrode group 20A having movable electrodes 21 facing each fixed electrode 11 of the first fixed electrode group 10A, and a second movable electrode group 20B having movable electrodes 22 facing each fixed electrode 12 of the second fixed electrode group 10B; and a frame part 30 connecting the movable electrode part 20 and the other end of the support beams 42 and 43. Furthermore, in the fixed electrode section forming process, the second fixed electrode group 10B is formed such that a second recess R2 recessed in the third direction DR3 is provided in the second fixed electrode group 10B. Furthermore, in the movable body forming process, the first movable electrode group 20A is formed such that a first recess R1 recessed in the third direction is provided in the first movable electrode group 20A, and the movable body MB is formed such that a third recess R3 recessed in the third direction DR3 is provided in the region on the side of the second movable electrode group 20B of the frame section 30.

[0111] In the physical quantity sensor 1 of this embodiment, in order to ensure the mobility of the movable body MB, a certain space needs to be provided inside the first detection element 100 of the physical quantity sensor 1. In this space, the movable body MB, the fixed electrode part 10, the support beams 42, 43 and other components are formed and arranged with high precision. In addition, in order to eliminate the non-uniformity of the mass of the movable body MB, a structure is adopted in which a first recess R1, a second recess R2 and a third recess R3 are provided. However, as mentioned above, there is also a need to process them together.

[0112] Regarding this point, according to this embodiment, such as Figure 15 As explained, the space inside the first detection element 100 can be set using the wafer bonding process after the cavity 202 is formed. Therefore, the complexity of processes such as removing temporarily deposited sacrificial films by wet etching can be avoided, reducing the difficulty of the process. While dry etching can result in surface roughness and reduced yield, these defects can be avoided. Furthermore, as described above, by adjusting the pattern of the third recess R3 in top view, the etching rate of the third recess R3 can be optimized, allowing each recess to be processed simultaneously, thus streamlining the manufacturing process and reducing costs.

[0113] As described above, the physical quantity sensor of this embodiment relates to a physical quantity sensor that detects physical quantities in the third direction when mutually orthogonal directions are defined as a first direction, a second direction, and a third direction. This physical quantity sensor includes a fixing part fixed to a substrate, a fixing electrode part provided on the substrate, a support beam connected to the fixing part at one end, and a movable body. The movable body has a movable electrode part and a frame part connecting the movable electrode part and the other end of the support beam. A first fixed electrode group and a second fixed electrode group are provided in the fixing electrode part. In the movable electrode part, a first movable electrode group is provided where each movable electrode faces each fixed electrode of the first fixed electrode group, and a second movable electrode group is provided where each movable electrode faces each fixed electrode of the second fixed electrode group. The frame part connects the movable electrode part and the other end of the support beam. Furthermore, a first recessed portion in the third direction is provided in the first movable electrode group, a second recessed portion in the third direction is provided in the second fixed electrode group, and a third recessed portion in the third direction is provided in the region of the frame part on the side of the second movable electrode group.

[0114] According to this embodiment, the mass inhomogeneity of the movable body of the physical quantity sensor on the first axis can be eliminated, and the center of gravity of the physical quantity sensor will not shift. Therefore, the sensitivity of the other axis of the physical quantity sensor can be reduced, thereby improving the detection accuracy of the physical quantity. In addition, a good physical quantity sensor with high long-term reliability can be provided, which is not easily affected by unwanted vibrations or impacts from the outside.

[0115] In addition, in this embodiment, the first recess and the third recess may have the same area when viewed from a third-party top view.

[0116] By making the depths of the first and third recesses equal, the non-uniformity of the inertial torque in the first direction, with the first direction as the rotation axis, can be eliminated. Therefore, the detection accuracy of the physical quantity sensor can be improved.

[0117] In addition, in this embodiment, the first recess and the third recess may have the same depth in the third direction.

[0118] In this way, by making the areas of the first and third recesses the same when viewed from above in a third direction, the volumes of the first and third recesses can be made equal. Therefore, the non-uniformity of the inertial torque about the first direction as the rotation axis in the first direction DR1 can be eliminated, improving the detection accuracy of the physical quantity sensor.

[0119] In addition, in this embodiment, the first recess and the third recess may also have the same volume.

[0120] In this way, the non-uniformity of the inertial torque I with the first direction as the rotation axis can be eliminated in the first direction DR1, thereby improving the detection accuracy of the physical quantity of the physical quantity sensor 1.

[0121] In addition, in this embodiment, the third recess can also be divided into multiple segmented recesses.

[0122] In this way, the third recess can be divided into multiple segmented recesses. Therefore, by adjusting the pattern of the third recess, the etching rates of the first and third recesses can be adjusted to be similar. Therefore, the first and third recesses can be machined to the same depth by processing them together. Therefore, the non-uniformity of the inertial torque of the movable body MB in the first direction can be eliminated with a simpler process, thereby improving the detection accuracy of physical quantities.

[0123] In addition, in this embodiment, the width of the dividing recess in the first direction may also be the same as the width of each movable electrode of the first movable electrode group in the first direction.

[0124] Thus, when the first recess is composed of multiple rectangular shapes, as long as the third recess has the same number of segmented recesses of the same width, the non-uniformity of the mass of the movable body in the first direction can be eliminated.

[0125] In addition, in this embodiment, the total area of ​​the multiple segmented recesses can also be the same as the area of ​​the first recess when viewed from a third-party top view.

[0126] In this way, by adjusting the pattern of the segmented recesses in the third direction, the etching rates of the first and third recesses can be made similar, allowing them to be processed together to achieve the same volume. Therefore, the detection sensitivity of physical quantity sensors can be improved using a simpler and lower-cost manufacturing process.

[0127] In addition, in this embodiment, the length of the first recess in the second direction may also be the same as the length of each movable electrode of the first movable electrode group in the second direction.

[0128] This allows for a wider area of ​​contact between the fixed and movable electrodes, enabling the detection of acceleration as a larger change in electrostatic capacitance. Therefore, it improves the detection sensitivity of the physical quantity sensor.

[0129] In addition, in this embodiment, the movable body includes: a first part, one end of which is connected to the other end of the support beam and extends in the second direction as the long side direction; and a second part, which is connected to one end of the first part and extends in the first direction as the long side direction.

[0130] In this way, a movable body in a roughly U-shape can be formed. Moreover, the movable body can move about a first direction as a rotation axis via the support beams 42 and 43, and the physical quantity sensor can detect the acceleration in the third direction.

[0131] In addition, in this embodiment, the movable electrode part is connected to the second part.

[0132] In this way, the movable electrode part can become an integral part of the second part of the frame and swing. Therefore, by the movement of the movable body about the first direction as the axis of rotation, the physical quantity sensor can detect the acceleration in the third direction.

[0133] In addition, in this embodiment, the third recess is provided in the second part.

[0134] This reduces the volume of a portion of the second part of the frame. Therefore, it eliminates the mass inhomogeneity of the movable body along the first direction caused by the first recess, thereby improving the detection accuracy of the physical quantity sensor.

[0135] Furthermore, this embodiment relates to an inertial measurement device that includes a physical quantity sensor as described above and a control unit that performs control based on the detection signal output from the physical quantity sensor.

[0136] Furthermore, the manufacturing method of this embodiment relates to the following manufacturing method, which includes: a fixed electrode part forming process, wherein a fixed electrode part is formed on a substrate of a physical quantity sensor, and the physical quantity sensor detects a physical quantity in the third direction when three mutually orthogonal directions are designated as a first direction, a second direction, and a third direction; and a movable body forming process, wherein a movable body is formed. The physical quantity sensor includes a fixing part fixed to a substrate, one end of a support beam connected to the fixing part, the fixed electrode part disposed on the substrate, and including a first fixed electrode group and a second fixed electrode group. The movable body includes: a movable electrode part, a first movable electrode group having each movable electrode facing each fixed electrode of the first fixed electrode group, and a second movable electrode group having each movable electrode facing each fixed electrode of the second fixed electrode group; and a frame part connecting the movable electrode part and the other end of the support beam. In the fixed electrode part forming process, the second fixed electrode group is formed such that a second recess recessed in the third direction is provided in the second fixed electrode group. In the movable body forming process, the first movable electrode group is formed by providing a first recess that is recessed to the third direction in the first movable electrode group, and the movable body is formed by providing a third recess that is recessed to the third direction in the region on the side of the second movable electrode group of the frame portion.

[0137] According to the manufacturing method of this embodiment, the complexity of the manufacturing process can be avoided by using a wafer bonding process, thereby reducing the difficulty of the process. Furthermore, by adjusting the pattern of the third recess when viewed from above, the etching rate of the third recess can be optimized, allowing for simultaneous processing of all recesses. Therefore, the manufacturing process can be streamlined and cost-effective.

[0138] Furthermore, as described above, this embodiment has been explained in detail; however, those skilled in the art will readily understand that various modifications are possible that substantially depart from the novel aspects and effects of the invention. Therefore, all such modifications are included within the scope of the invention. For example, in the specification or drawings, a term described at least once with a different, broader or synonymous term may be replaced with that different term anywhere in the specification or drawings. Furthermore, all combinations of this embodiment and its modifications are included within the scope of the invention. Additionally, the structure, operation, etc., of the physical quantity sensor, inertial measurement device, and manufacturing method are not limited to those described in this embodiment, and various modifications can be implemented.

Claims

1. A physical quantity sensor, characterized in that, When mutually orthogonal directions are defined as the first direction, the second direction, and the third direction, the physical quantity sensor detects the physical quantity in the third direction. The physical quantity sensor includes: The fixing part is fixed to the substrate; A support beam, one end of which is connected to the fixing part; A fixed electrode section is disposed on a substrate and includes a first fixed electrode group and a second fixed electrode group; and A movable body includes a movable electrode section and a frame section. The movable electrode section includes a first movable electrode group and a second movable electrode group. The frame section connects the movable electrode section to the other end of the support beam. The first fixed electrode group includes a plurality of first fixed electrodes, which are configured in a comb-like shape. The second fixed electrode group includes a plurality of second fixed electrodes, which are configured in a comb-like shape. The first movable electrode group is disposed opposite to the first fixed electrode group in the second direction. The first movable electrode group includes a plurality of first movable electrodes, which are configured in a comb-like shape. The second movable electrode group is disposed opposite to the second fixed electrode group in the second direction. The second movable electrode group includes a plurality of second movable electrodes, which are configured in a comb-like shape. Each of the first fixed electrodes is located between adjacent first movable electrodes. Each of the second fixed electrodes is located between adjacent second movable electrodes. Each of the first movable electrodes is provided with a first recess that is recessed toward the third party. Each of the second fixed electrodes is provided with a second recess that is recessed toward the third party. A third recess is provided only in the region on the side of the second movable electrode group of the frame portion, which is recessed toward the third party. The first fixed electrode without the second recess is located between the adjacent first movable electrodes with the first recess. The second fixed electrode, which has the second recess, is located between adjacent second movable electrodes that do not have the first recess.

2. The physical quantity sensor according to claim 1, characterized in that, When viewed from above by the third party, the area of ​​the first recess is the same as the area of ​​the third recess.

3. The physical quantity sensor according to claim 2, characterized in that, The third-direction depth of the first recess is the same as the third-direction depth of the third recess.

4. The physical quantity sensor according to claim 1, characterized in that, The volume of the first recess is the same as the volume of the third recess.

5. The physical quantity sensor according to claim 3 or 4, characterized in that, The third recess is divided into multiple segmented recesses.

6. The physical quantity sensor according to claim 5, characterized in that, The width of the segmented recess in the first direction is the same as the width of the first movable electrode in the first direction.

7. The physical quantity sensor according to claim 5, characterized in that, When viewed from above by the third party, the total area of ​​the plurality of segmented recesses is the same as the area of ​​the first recess.

8. The physical quantity sensor according to claim 1, characterized in that, The length of the first recess in the second direction is the same as the length of the first movable electrode in the second direction.

9. The physical quantity sensor according to claim 1, characterized in that, The movable body includes: The first part, with one end connected to the other end of the support beam and arranged along the second direction; and The second part is connected to one end of the first part and is configured along the first direction.

10. The physical quantity sensor according to claim 9, characterized in that, The movable electrode section is connected to the second part.

11. The physical quantity sensor according to claim 9 or 10, characterized in that, The third recess is provided in the second part.

12. An inertial measurement device, characterized in that, include: The physical quantity sensor according to any one of claims 1 to 11; as well as The control unit performs control based on the detection signal output from the physical quantity sensor.

13. A manufacturing method, characterized in that, This is a method for manufacturing a physical quantity sensor. When three mutually orthogonal directions are designated as a first direction, a second direction, and a third direction, the physical quantity sensor detects physical quantities in the third direction. The manufacturing method includes: A process for forming a fixed electrode portion on a substrate; and The movable body forming process that forms a movable body. The physical quantity sensor includes a fixing part fixed to the substrate. One end of the support beam is connected to the fixing part. The fixed electrode portion is disposed on the substrate and includes a first fixed electrode group and a second fixed electrode group. The movable body includes: The movable electrode section includes a first movable electrode group and a second movable electrode group; and The frame section connects the movable electrode section and the other end of the support beam. The first fixed electrode group includes a plurality of first fixed electrodes, which are configured in a comb-like shape. The second fixed electrode group includes a plurality of second fixed electrodes, which are configured in a comb-like shape. The first movable electrode group is disposed opposite to the first fixed electrode group in the second direction. The first movable electrode group includes a plurality of first movable electrodes, which are configured in a comb-like shape. The second movable electrode group is disposed opposite to the second fixed electrode group in the second direction. The second movable electrode group includes a plurality of second movable electrodes, which are configured in a comb-like shape. Each of the first fixed electrodes is located between adjacent first movable electrodes. Each of the second fixed electrodes is located between adjacent second movable electrodes. In the fixed electrode forming process, the second fixed electrode group is formed such that a second recess is provided in each of the second fixed electrodes, which is recessed toward the third party. The movable body forming process forms the first movable electrode group by providing a first recessed portion in the third direction in each of the first movable electrodes, and forms the movable body by providing a third recessed portion in the third direction only in the region on the side of the second movable electrode group in the frame portion. The first fixed electrode without the second recess is located between the adjacent first movable electrodes with the first recess. The second fixed electrode, which has the second recess, is located between adjacent second movable electrodes that do not have the first recess.

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