Physical quantity sensor, inertial measuring device, and manufacturing method

Abstract

To provide a physical quantity sensor or the like, that can avoid trouble associated with non-uniformity of mass of a movable body.SOLUTION: A physical quantity sensor 1 detects a physical quantity in a third direction, and includes a stationary electrode part 10, a stationary part 40 fixed to a substrate 2, support beams 42, 43 connected at one ends with the stationary part 40, and a movable body MB. The movable body MB has a movable electrode part 20 and a frame part 30. The stationary electrode part 10 is provided with a first stationary electrode group 10A and a second stationary electrode group 10B. The movable electrode part 20 is provided with a first movable electrode group 20A and a second movable electrode group 20B. The first movable electrode group 20A is provided with first recesses R1 recessed in the third direction DR3. The second stationary electrode group 10B is provided with second recesses R2 recessed in the third direction DR3. An area of the frame part 30 on the side of the second movable electrode group 20B is provided with third recesses R3 recessed in the third direction DR3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a physical quantity sensor, an inertial measurement device, a manufacturing method, and the like.

Background Art

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

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the physical quantity sensor disclosed in Patent Document 1, when two or more stators are provided, the thickness of the comb teeth electrodes of the rotor is changed for each rotor corresponding to each stator. Therefore, the center of gravity balance of the movable body with respect to the rotation axis may be disrupted, and the sensitivity to other axes may increase.

Means for Solving the Problems

[0005] One aspect of the present disclosure relates to a physical quantity sensor for detecting a physical quantity in a third direction, where mutually orthogonal directions are defined as a first direction, a second direction, and a third direction, and includes a movable body having: a fixed part fixed to a substrate; a support beam with one end connected to the fixed part; a fixed electrode part provided on the substrate and provided with a first fixed electrode group and a second fixed electrode group; a movable electrode part provided with a first movable electrode group in which each fixed electrode of the first fixed electrode group faces a movable electrode, and a second movable electrode group in which each fixed electrode of the second fixed electrode group faces a movable electrode; and a frame part connecting the movable electrode part and the other end of the support beam, wherein the first movable electrode group is provided with a first recess that recesses in the third direction, the second fixed electrode group is provided with a second recess that recesses in the third direction, and a third recess that recesses in the third direction is provided in the region of the frame part on the side of the second movable electrode group.

[0006] Another aspect of this disclosure relates to an inertial measuring device that includes the physical quantity sensor described above and a control unit that performs control based on a detection signal output from the physical quantity sensor.

[0007] Another aspect of the present disclosure relates to a method for manufacturing a physical quantity sensor for detecting a physical quantity in a third direction, where three mutually orthogonal directions are designated as a first direction, a second direction, and a third direction, comprising: a fixed electrode portion forming step of forming a fixed electrode portion on a substrate; and a movable body forming step of forming a movable body, wherein the physical quantity sensor includes a fixed portion fixed to the substrate, a support beam with one end connected to the fixed portion, the fixed electrode portion provided on the substrate and including a first fixed electrode group and a second fixed electrode group, and the movable body is a first movable electrode group and a second fixed electrode group in which each movable electrode faces each fixed electrode of the first fixed electrode group. The present invention relates to a manufacturing method comprising a movable electrode section in which a second movable electrode group is provided, each of which movable electrodes faces a fixed electrode, and a frame section connecting the movable electrode section and the other end of the support beam, wherein in the fixed electrode section forming step, the second fixed electrode group is formed such that the second fixed electrode group is provided with a second recess that is recessed in the third direction, and in the movable body forming step, the first movable electrode group is formed such that the first movable electrode group is provided with a first recess that is recessed in the third direction, and the movable body is formed such that a third recess that is recessed in the third direction is provided in the region of the frame section on the side of the second movable electrode group. [Brief explanation of the drawing]

[0008] [Figure 1] An example configuration of the physical quantity sensor in this embodiment. [Figure 2] A perspective view illustrating the three-dimensional shape of the first recess. [Figure 3] A perspective view illustrating the three-dimensional shape of the second recess. [Figure 4] Operational diagram of the detection unit. [Figure 5] An explanatory diagram illustrating the effect of mass non-uniformity in a movable body. [Figure 6] An explanatory diagram illustrating the effect of mass non-uniformity in a movable body. [Figure 7] An explanatory diagram illustrating the effect of mass non-uniformity in a movable body. [Figure 8] A plan view showing the first detailed example of a physical quantity sensor. [Figure 9] A plan view showing a second detailed example of a physical quantity sensor. [Figure 10]Plan view showing a modification of the second detailed example of the physical quantity sensor. [Figure 11] Exploded perspective view showing a schematic configuration of an inertial measurement device having a physical quantity sensor. [Figure 12] Perspective view of the circuit board of the inertial measurement device. [Figure 13] Plan view of the physical quantity sensor of the present embodiment. [Figure 14] Explanatory drawing of the manufacturing method of the physical quantity sensor of the present embodiment. [Figure 15] Explanatory drawing of the manufacturing method of the physical quantity sensor of the present embodiment. [Figure 16] Explanatory drawing of the manufacturing method of the physical quantity sensor of the present embodiment. [Figure 17] Explanatory drawing of the manufacturing method of the physical quantity sensor of the present embodiment. [Figure 18] Explanatory drawing of the manufacturing method of the physical quantity sensor of the present embodiment. [Figure 19] Explanatory drawing of the manufacturing method of the physical quantity sensor of the present embodiment. [Figure 20] Explanatory drawing of the manufacturing method of the physical quantity sensor of the present embodiment. [Figure 21] Explanatory drawing of the manufacturing method of the physical quantity sensor of the present embodiment. [Figure 22] Explanatory drawing of the manufacturing method of the physical quantity sensor of the present embodiment.

Mode for Carrying Out the Invention

[0009] Hereinafter, the present embodiment will be described. Note that the present embodiment described below does not unduly limit the contents described in the claims. Also, not all of the configurations described in the present embodiment are essential constituent elements.

[0010] 1. Physical Quantity Sensor An example of the configuration of the physical quantity sensor 1 in this embodiment will be described with reference to Figure 1, using an acceleration sensor that detects vertical acceleration as an example. Figure 1 is a plan view of the physical quantity sensor 1 in a direction perpendicular to the substrate 2. The physical quantity sensor 1 is a MEMS (Micro Electro Mechanical Systems) device, such as an inertial sensor.

[0011] Note that in Figure 1 and the following Figures 2-10 and 13-22, for the sake of explanation, the dimensions of each component and the spacing between components are shown schematically, and not all components are shown. For example, electrode wiring and electrode terminals are omitted from the illustration. Furthermore, the explanation below mainly uses the case where the physical quantity detected by the physical quantity sensor 1 is acceleration as an example, but the physical quantity is not limited to acceleration and may be other physical quantities such as velocity, pressure, displacement, angular velocity, or gravity, and the physical quantity sensor 1 may be used as a pressure sensor or a MEMS switch, etc. Also, in Figure 1, the mutually orthogonal directions are referred to 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, which corresponds to the Z-axis direction, is, for example, the direction orthogonal to the substrate 2 of the physical quantity sensor 1, for example, the vertical direction. Furthermore, the fourth direction DR4 is the opposite direction to the third direction DR3, for example, the negative direction in 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 perpendicular to the third direction DR3, and the XY plane, which is the plane along the first direction DR1 and the second direction DR2, is, for example, along the horizontal plane. Note that "perpendicular" includes not only cases where they intersect at 90°, but also cases where they intersect at an angle slightly tilted from 90°.

[0012] The substrate 2 is, for example, a silicon substrate made of semiconductor silicon or a glass substrate made of a glass material such as borosilicate glass. However, the constituent material of the substrate 2 is not particularly limited, and a quartz substrate or an SOI (Silicon On Insulator) substrate may also be used.

[0013] As shown in Figure 1, the physical quantity sensor 1 of this embodiment includes a fixed electrode section 10, a movable body MB, a fixed section 40, and support beams 42 and 43. The movable body MB includes a movable electrode section 20 and a frame section 30, and the frame section 30 includes two first sections 31 extending with the second direction DR2 as the long side direction, and one second section 32 extending with the first direction DR1 as the long side direction.

[0014] The fixed electrode section 10, the movable electrode section 20, the frame section 30, the fixed section 40, and the support beams 42 and 43 constitute the first detection element 100 of the physical quantity sensor 1. The first detection element 100 detects a physical quantity, such as acceleration, in the third direction DR3, which is the Z-axis direction, at the detection section ZA and detection section ZB.

[0015] 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 each provided on the substrate 2. The first fixed electrode group 10A and the second fixed electrode group 10B are each fixed to the substrate 2 by fixing parts. 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 along a second direction DR2, which is, for example, the Y-axis direction. That is, the plurality of fixed electrodes 11 are arranged in a comb-like manner, and these constitute the first fixed electrode group 10A. Similarly, the plurality of fixed electrodes 12 are arranged in a comb-like manner, and these constitute the second fixed electrode group 10B. In the following explanation, the fixed electrode 11 of the first fixed electrode group 10A and the fixed electrode 12 of the second fixed electrode group 10B will be collectively referred to as fixed electrode 14 as appropriate.

[0016] 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 and 22 extend from the second portion 32 of the frame section 30 along a second direction DR2, for example, the Y-axis direction. The plurality of movable electrodes 21 are arranged in a comb-like manner, constituting the first movable electrode group 20A, and the plurality of movable electrodes 22 are arranged in a comb-like manner, constituting the second movable electrode group 20B. Each movable electrode 21 of the first movable electrode group 20A is arranged to face each fixed electrode 11 of the first fixed electrode group 10A in the first direction DR1, which is the X direction. Similarly, each movable electrode 22 of the second movable electrode group 20B is arranged to face each fixed electrode 12 of the second fixed electrode group 10B in the first direction DR1. Furthermore, the portion where the fixed electrode 11 and the movable electrode 21 are arranged to face each other in the first direction DR1 corresponds to the detection portion ZA of the first detection element 100, and the portion where the fixed electrode 12 and the movable electrode 22 are arranged to face each other in the first direction DR1 corresponds to the detection portion 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.

[0017] The movable body MB moves with the first direction DR1, which is along the support beams 42 and 43, as its axis of rotation.

[0018] Here, the support beams 42 and 43 are, for example, torsion springs, and one end of each support beam 42 and 43 is fixed to the base plate 2 by a fixing part 40. In Figure 1, there are two support beams 42 and 43 along the first direction DR1, with support beam 42 extending from the fixing part 40 in the direction opposite to the first direction DR1 and support beam 43 extending from the fixing part 40 toward the first direction DR1. 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 that are not connected to the fixing part 40. Thus, the movable body MB has a roughly U-shape formed by the two first parts 31 and one second part 32 of the frame part 30, and is connected to the fixing part 40 via the support beams 42 and 43.

[0019] The movable body MB is configured in this way, with support beams 42 and 43, designed to rotate around the axis of rotation, receiving a force in the third direction DR3 and twisting along the axis of the first direction DR1, thereby enabling it to swing in the third direction DR3. Then, with the fixed part 40 as an anchor, the movable body MB swings, realizing a first detection element 100 with a so-called one-sided seesaw structure.

[0020] Furthermore, the frame section 30 is designed so that the mass of the tip section, i.e., the second section 32, is large, resulting in a large moment of inertia I about the axis of rotation.

[0021] Furthermore, in the physical quantity sensor 1 shown in Figure 1, the movable electrode 21 of the first movable electrode group 20A is provided with a first recess R1. Figure 2 is a perspective view illustrating the three-dimensional shape of the first recess R1. As shown in Figure 2, the movable electrode 21 has a recess in part of its thickness in the third direction DR3. Specifically, in the second direction DR2, the thickness in the third direction DR3 is thinner only in the area shown by a in Figure 2. Thus, the movable electrode 21 has the same thickness as the frame portion 30 in the third direction DR3 up to a certain range from the connection part with the second portion 32 of the frame portion 30, but the thickness in the third direction DR3 is thinner mainly in the region facing the fixed electrode 11 of the first fixed electrode group 10A. The detection unit ZA includes a fixed electrode 11 and a movable electrode 21 with different thicknesses in the third direction DR3 in this way.

[0022] Furthermore, the fixed electrode 12 of the second fixed electrode group 10B of the physical quantity sensor 1 shown in Figure 1 is provided with a second recess R2. Figure 3 is a perspective view illustrating the three-dimensional shape of the second recess R2. As shown in Figure 3, the fixed electrode 12 has a recess in part of its thickness in the third direction DR3. Specifically, in the region indicated by b in Figure 3, the thickness of the fixed electrode 12 in the third direction DR3 is the same as the thickness of the base portion of the comb-tooth electrode of the second fixed electrode group 10B. However, the thickness of the fixed electrode 12 in the third direction DR3 outside the region indicated by b is thinner. The detection unit ZB includes a fixed electrode 12 and a movable electrode 22 with such different thicknesses in the third direction DR3. The fixed electrodes 11 and 12 are, for example, approximately 10 μm to 40 μm thick.

[0023] Furthermore, in the physical quantity sensor 1 shown in Figure 1, a third recess R3 is provided in a part of the second portion 32 of the frame portion 30 of the movable body MB. Specifically, as shown in the perspective view of Figure 3, the third recess R3 is a recess in which a part of the second portion 32 of the frame portion 30 on the third direction DR3 side is recessed. As will be explained in detail in Figures 14 to 22 below, in this embodiment, the first recess R1, the second recess R2, and the third recess R3 are formed by a single etching process and are assumed to have the same depth.

[0024] Figure 4 is an explanatory diagram of the operation of the detection units ZA and ZB in the first detection element 100. Figure 4 shows the movement of the fixed electrodes 11 and 12 and the movable electrodes 21 and 22 in cross-sectional views along the XZ plane for the initial state and the state in which acceleration is occurring, when the direction of acceleration is the third direction DR3 and when the direction of acceleration is the fourth direction DR4, respectively. The initial state is the state in which no acceleration, including gravity, is occurring in the third direction DR3.

[0025] In the initial state, in a side view in the second direction DR2, the movable electrodes 21 and 22 and the fixed electrodes 11 and 12 are flush with each other, with their ends on the fourth direction DR4 side aligned, in both the detection units ZA and ZB. As mentioned above, the movable electrode 21 of the movable electrode unit 20 is provided with a first recess R1, and the fixed electrode 12 of the fixed electrode unit 10 is provided with a second recess R2. Therefore, as shown in the initial state, the fixed electrodes 11 and 12 and the movable electrodes 21 and 22 are not positioned flush with each other, with their ends on the third direction DR3 side aligned, in a side view in the second direction DR2.

[0026] Next, in the state where acceleration occurs 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 each subjected to inertial force associated with the acceleration and are displaced toward 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 as the movable electrode 21 is displaced toward the fourth direction DR4. 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 is movable electrode 22 Since there is no recess, the movable electrode 22 remains constant even when displaced in the fourth direction DR4. In this way, when acceleration occurs in the third direction DR3, the opposing area decreases in the detection unit ZA, while the opposing area is maintained in the detection unit ZB.

[0027] 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 each subjected to inertial force associated with the acceleration and are displaced toward 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 is maintained constant because the first recess R1 is provided in 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 as the movable electrode 22 is displaced toward the fourth direction DR4. Thus, when acceleration occurs in the fourth direction DR4, the detection unit Z A The opposing surface area is maintained, while the opposing surface area decreases in the detection unit ZB.

[0028] Thus, when acceleration in the third direction DR3 occurs, the opposing area between the fixed electrode 11 and the movable electrode 21 in the detection unit ZA decreases, and when acceleration in the fourth direction DR4 occurs, the opposing area between the fixed electrode 12 and the movable electrode 22 in the detection unit ZB decreases. Therefore, by detecting the decrease in the opposing area in the detection units ZA and ZB as a change in capacitance between the fixed electrode 14 and the movable electrode 24, acceleration in the third direction DR3 and the fourth direction DR4 can be detected.

[0029] The fixed electrode 11 of the first fixed electrode group 10A and the movable electrode 21 of the first movable electrode group 20A are positioned opposite each other, forming a parallel-plate type capacitance in the detection unit 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 positioned opposite each other, forming a parallel-plate type capacitance in the detection unit ZB. Then, for example, the change in capacitance in the detection unit ZA is measured on the N side and the detection unit Z B The change in capacitance at this point can be detected as the P side.

[0030] As shown in Figure 4 when the acceleration direction is the third direction DR3, when acceleration in the third direction DR3 occurs in the physical quantity sensor 1, the movable electrode 24 is displaced towards the fourth direction DR4 due to inertial force. At this time, the area of ​​the detection unit ZB, i.e., the area of ​​the fixed electrode 12 on the P side and the movable electrode 22 facing each other, does not change, so the capacitance does not change. On the other hand, the area of ​​the detection unit ZA, i.e., the area of ​​the fixed electrode 11 on the N side and the movable electrode 21 facing each other, decreases. Therefore, by detecting the difference in capacitance between the P side and the N side using a differential amplifier circuit QV (not shown), a detection signal for acceleration in the third direction DR3 can be obtained. When acceleration in the fourth direction DR4 occurs, the opposite is true: the area of ​​the detection unit ZB, i.e., the area of ​​the fixed electrode 12 on the P side and the movable electrode 22 facing each other decreases, and the capacitance decreases, while the area of ​​the detection unit ZA, i.e., the area of ​​the fixed electrode 11 on the N side and the movable electrode 21 facing each other, does not change, and the capacitance does not change. Therefore, by detecting this using the differential amplifier circuit QV, a detection signal for acceleration in the fourth direction DR4 can be obtained. Capacitance detection can be achieved, for example, by connecting a first fixed electrode group 10A to a differential amplifier circuit QV (not shown) via wiring LFA and pad PFA (not shown), a second fixed electrode group 10B to a wiring LFB and pad PFB (not shown), and a movable body MB to a wiring LV and pad PV (not shown).

[0031] As explained above, 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, acceleration 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 configuration. For example, by providing a first recess R1 on the fixed electrode 11 of the detection unit ZA, acceleration in the fourth direction DR4 can be detected in the detection unit ZA, and by providing a second recess R2 on the movable electrode 22 of the detection unit ZB, acceleration in the third direction DR3 can be detected in the detection unit ZB.

[0032] 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, acceleration in the third direction DR3 and the fourth direction DR4 can be detected. Now, focusing on the motion of the movable body MB with the first direction DR1 as the axis of rotation, the question arises whether the first recess R1 provided in the first movable electrode group 20A of the movable body MB will affect the motion of the movable body MB. That is, the frame portion 30 is lighter on the N side by the volume of the first recess R1, and the center of gravity balance of the movable body MB is poor, which may cause problems in the motion of the movable body MB.

[0033] First, considering the moment of inertia I of the movable body MB around the X-axis, since the moment of inertia I is the product of the square of the distance from the axis of rotation and the mass, if the first recess R1 and the third recess R3 are not provided, the moment of inertia I is uniform along the X-axis. 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 decreases due to the first recess R1, but in the region where the second movable electrode group 20B is provided, there is no recess, so it remains unchanged. Thus, the moment of inertia I of the movable body MB becomes non-uniform along the X-axis.

[0034] Next, with respect to the cross-section AA' of the physical quantity sensor 1 in Figure 1, the case in which the third recess R3 is not provided in the frame portion 30 will be explained using Figure 5. Figure 5 shows a weightless state in which there is no gravitational acceleration in the Z direction. In this case, the line segment connecting the center O of the frame portion 30 and the first movable electrode group 20A intersects the X axis at an angle α, and the line segment connecting the center O of the frame portion 30 and the second movable electrode group 20B intersects the X axis at an angle β. Since the first movable electrode group 20A is provided with the first recess R1, the angle α has a constant value, but since the second movable electrode group 20B is not provided with a recess, its center of gravity is on the X axis and the angle β is 0. Figure 6 shows the cross-section AA' of the physical quantity sensor 1 being subjected to gravitational acceleration in the Z direction. As described above, because the moment of inertia I is non-uniform along the X axis, the amount of displacement in rotational motion with the X axis as the axis of rotation will be different in the region of the first movable electrode group 20A and the region of the second movable electrode group 20B. Therefore, the gravitational force F1 acting on the first movable electrode group 20A due to acceleration and the gravitational force F2 acting on the region of the second movable electrode group 20B are also different. In this case, the second movable electrode group 20B has a larger mass, heavy Force F2 is better heavy The force becomes greater than 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 thus balance with a constant elastic deformation. Therefore, due to the gravitational forces F1 and F2 of different magnitudes, the upper and lower end surfaces of the movable body MB balance at an angle θ from the X-axis direction, as shown in Figure 6. Consequently, the physical quantity sensor 1 deviates slightly from the ideal rotational motion shown in Figure 4. This particularly affects the linearity of the acceleration sensitivity. However, this deviation in the linearity of the sensitivity can be corrected. Note that Figure 6 and Figure 7, described later, show the aforementioned deviation of the rotation axis enlarged in order to visualize the effect of the mass non-uniformity of the movable body MB.

[0035] Next, we consider the case where the movable body MB, which is subjected to gravitational acceleration as explained in Figure 6, is subjected to a force in a direction other than the Z direction, for example, the X direction, causing acceleration. The movable body MB is connected to the other ends of support beams 42 and 43, one end of which is fixed to the fixed part 40, and can basically only move in the Z direction, so even if it is subjected to a force in the X direction, it does not affect the detection of acceleration in the Z axis direction.

[0036] However, as explained in Figures 5 and 6, 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 from the center O of the frame 30 to each part of the movable body MB and the inertial force that each part of the movable body MB experiences due to acceleration. Specifically, we consider the torque obtained by the cross product of the position vector from the center O of the frame 30 to each part of the movable body MB and the inertial force vector that each part of the movable body MB experiences due to acceleration in the X direction. Figure 7 shows the inertial forces acting on the first movable electrode group 20A and the second movable electrode group 20B of the physical quantity sensor 1 as vectors when acceleration in the first direction DR1 occurs. The inertial force F3 acting on the part of the first movable electrode group 20A where the first recess R1 is provided is a vector in the -X direction, and the inertial force F4 acting on the part of the second movable electrode group 20B where the recess is not provided 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 and the position vector r from the center O are considered. 20A The cross product is r 20A It is expressed as F3sinθ. On the other hand, for the second movable electrode group 20B, the inertial force F4 vector in the -X direction and the position vector r from the center O are used. 20B The cross product is r 20B It is expressed as F4sin(π+θ). However, in this case, the angle θ at which the upper and lower ends of the movable body MB intersect with the X-axis was assumed to be much larger than the angles α and β in Figure 5. That is, θ >> α, β. Since the distance from the center O to each group of movable electrodes is equal, r 20A =r 20BIf we set = r, the torque that the movable body MB receives around the fixed part 40 is expressed as r(F3-F4)sinθ. Here, the second movable electrode group 20B, which does not have a recess, has a larger mass than the first movable electrode group 20A, which has a first recess R1. Therefore, the inertial force F4 acting on the second movable electrode group 20B is greater than the inertial force F3 acting on the first movable electrode group 20A, and the torque r(F3-F4)sinθ becomes a negative value. Consequently, the movable body MB is subjected to a torque r(F3-F4)sinθ with the Y-axis as the axis of rotation. Thus, in addition to the acceleration in the Z direction with the X-axis as the axis of rotation as originally intended by the physical quantity sensor 1, a component of rotational motion with the Y-axis as the axis of rotation is generated.

[0037] Thus, if the moment of inertia I of the movable body MB is non-uniform along the X-axis, it may, in combination with the elasticity of the support beams 42 and 43, cause the physical quantity sensor 1 to undergo unwanted rotational motion, potentially increasing the sensitivity across axes. This phenomenon is particularly pronounced when the sensor is subjected to gravitational acceleration in the Z-direction. Note that sensitivity across axes refers to the sensitivity with which a physical quantity sensor detects physical quantities in directions other than the direction it is intended to detect, as if they were physical quantities in the intended direction.

[0038] The physical quantity sensor disclosed in Patent Document 1 comprises a rotor corresponding to a movable body MB and a plurality of stators corresponding to a fixed electrode portion 10. At least a portion of the rotor and the plurality of stators is partially concave in thickness in the Z direction. Consequently, non-uniformity of the moment of inertia I with respect to the rotation axis of the rotor occurs, which may increase the sensitivity in other axes as described above. Thus, in a physical quantity sensor that detects acceleration in the Z direction, if the thickness of the electrodes in the third direction DR3 of the fixed electrode 14 and the movable electrode 24 is made different, non-uniformity of the moment of inertia I of the movable body MB including the movable electrode portion 20 occurs, which increases the sensitivity in other axes and deteriorates the detection accuracy of the physical quantity sensor.

[0039] In this regard, 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. The third recess R3 is provided on the side of the second portion 32 of the frame portion 30 that is in the first direction DR1. In the physical quantity sensor 1, since the first recess R1 is provided on the side of the second portion 32 of the frame portion 30 that is in the direction opposite to the first direction DR1, the moment of inertia 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, on the X axis opposite to the position where the first recess R1 is provided and on the X axis, the non-uniformity of the moment of inertia I of the movable body MB can be eliminated. That is, by providing the third recess R3, the non-uniformity of mass in the first direction DR1 of the second portion of the frame portion 30 is eliminated. Therefore, the deviation of rotational motion due to acceleration in the third direction DR3 of the physical quantity sensor 1 can be corrected. The shape of the third recess R3 can be designed as appropriate. For example, the shape of the third recess R3 in plan view may be rectangular or circular. It can also be provided discretely, as will be explained in the first detailed example below.

[0040] As described above, the physical quantity sensor 1 of this embodiment has a fixing part 40 fixed to the substrate 2, A fixed electrode section 10 is provided on the substrate 2 and is provided with a first fixed electrode group 10A and a second fixed electrode group 10B, It includes support beams 42 and 43, one end of which is connected to the fixed part 40, and a movable body MB. The movable body MB is , 1st movable electrode group 20A The movable electrode section 20 is provided with the second movable electrode group 20B, Movable electrode part 20 and The movable electrode section 20 includes a frame section 30 that connects to the other ends of the support beams 42 and 43. The movable electrode section 20 includes a first movable electrode group 20A in which each movable electrode 21 faces each fixed electrode 11 of the first fixed electrode group 10A, and a second movable electrode group 20B in which each movable electrode 22 faces each fixed electrode 12 of the second fixed electrode group 10B. The first movable electrode group 20A is provided with a first recess R1 that is recessed in the third direction DR3, the second fixed electrode group 10B is provided with a second recess R2 that is recessed in the third direction DR3, and a third recess R3 that is recessed in the third direction DR3 is provided in the region of the frame section 30 on the side of the second movable electrode group 20B.

[0041] In this way, since the first recess R1 and the third recess R3 have the same area and 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 is eliminated. As a result, the center of gravity of the physical quantity sensor in the third direction DR3 does not shift. Therefore, displacement when a physical quantity other than the third direction DR3 is applied, such as acceleration, can be suppressed. Thus, the sensitivity of the physical quantity sensor 1 to other axes can be reduced, and the detection accuracy of physical quantities can be improved. In addition, unwanted vibrations are less likely to occur due to external vibrations and shocks, and a good physical quantity sensor with high long-term reliability can be provided.

[0042] Furthermore, in this embodiment, the first recess R1 and the third recess R3 can have the same area in a plan view in the third direction DR3. By doing so, the depths of the first recess R1 and the third recess R3 can be made the same, which eliminates the non-uniformity of the moment of inertia I in the first direction DR1 with the first direction DR1 as the axis of rotation, and improves the detection accuracy of the physical quantity sensor 1.

[0043] As explained in Figures 20 and 21 below, the first recess R1 of the first movable electrode group 20A and the third recess R3 of the frame portion 30 can be formed by etching the same silicon deposition layer. Therefore, if the areas of the first recess R1 and the third recess R3 are designed to be the same in a plan view 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 by 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 individually and processed to the same depth. In this way, the non-uniformity of the mass of the movable body MB of the physical quantity sensor 1 on the axis in the first direction DR1 can be eliminated. Note that dimensions in the semiconductor manufacturing process vary by approximately ±10% to ±20% due to process variations, so the above-mentioned identical area includes cases where the area is approximately the same. 3 Recessed R 3 If it is divided, the area is the third in the plan view of the third direction DR3. 3 Recessed R 3This refers to the sum of the areas. Thus, in this embodiment, "identical" includes "approximately identical." For example, in this embodiment, identical area, identical volume, and identical length means that they are identical as design values, and may be approximately identical within the error range due to variations in the manufacturing process or tolerances.

[0044] Furthermore, in this embodiment, the first recess R1 and the third recess R3 may have the same depth in the third direction DR3. By doing so, the areas of the first recess R1 and the third recess R3 in a plan view in the third direction DR3 are made the same, thereby making the volumes of the first recess R1 and the third recess R3 equal. Consequently, the non-uniformity of the moment of inertia I in the first direction DR1 when the first direction DR1 is the axis of rotation is eliminated, and the detection accuracy of the physical quantity sensor 1 can be improved.

[0045] As described above, if the areas of the first recess R1 and the third recess R3 are the same in a plan view in the third direction DR3, and the 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 will be the same. Furthermore, since the silicon deposition layer is processed together with the first recess R1 and the third recess R3, the mass of the portion removed by processing will be equal in each of the first recess R1 and the third recess R3. Therefore, the non-uniformity of the volume of the movable body MB along the X axis is eliminated, and the above effect is achieved. Note that the depths of the first recess R1, the second recess R2, and the third recess R3 described above refer to the depth processed from the outermost layer of the wafer 208 in Figure 20, which will be described later.

[0046] 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 moment of inertia I in the first direction DR1 when the first direction DR1 is the axis of rotation, and improves the detection accuracy of the physical quantity sensor 1. Here, volume refers to the volume corresponding to the portion of the silicon deposit layer that originally existed when the first recess R1 and the third recess R3 were formed by processing such as etching.

[0047] 2. Detailed Configuration Example Figure 8 is a plan view of the first detailed example of this embodiment. The configuration of the third recess R3 differs from the configuration example shown in Figure 1. Specifically, in the first detailed example, the third recess R3 is divided into four segmented recesses in a plan view in the third direction DR3. Each segmented recess has a rectangular shape with the second direction DR2 as its longitudinal direction in a plan view in the third direction.

[0048] As described above, the physical quantity sensor 1 of this embodiment improves the detection accuracy of physical quantities in the third direction DR3 by making the volumes of the first recess R1 and the third recess R3 equal, thereby making the moment of inertia I of the movable body MB along the first direction DR1 uniform. Therefore, for example, if the area of ​​the first recess R1 and the area of ​​the third recess R3 are designed to be equal in a plan view in the third direction DR3, the volumes of the first recess R1 and the third recess R3 can be made equal by machining them so that their depths are equal.

[0049] Here, it is known that if the aperture patterns in the third direction DR3 of the first recess R1 and the third recess R3 are different in a plan view, even if etching is performed under the same etching conditions, differences in the etching rate in each recess will occur due to the microloading effect. Furthermore, even if the first recess R1 and the third recess R3 have the same aperture pattern in a plan view, differences in the surrounding exposure patterns and differences in position within the wafer or chip will also affect the etching rate of each recess. Therefore, simply making the area of ​​the first recess R1 in a plan view the same as the total area of ​​the divided recesses of the third recess R3, and performing etching under the same time and gas atmosphere conditions, will not necessarily result in equal volumes for each recess.

[0050] From this perspective, when we examine the physical quantity sensor 1 shown in Figure 1, the third recess R3 is a single, undivided recess, and in a plan view in the third direction DR3, it has a wide, open rectangular shape. On the other hand, the first recess R1 is originally part of the narrow pattern of the movable electrode 21 of the first movable electrode group 20A, and in a plan view, it has a pattern of multiple rectangular shapes arranged in a row with the second direction DR2 as the longitudinal direction. Furthermore, while the third recess R3 is processed from a part of the silicon deposition layer, the area surrounding the first recess R1 is generally assumed to be made of a material other than the silicon deposition layer. Thus, the processing pattern or the material surrounding the recesses differs between the first recess R1 and the third recess R3. Therefore, even if the first recess R1 and the third recess R3 are processed for the same amount of time under the same etching conditions, the depth of each recess will not be the same. In this case, even if the area of ​​the first recess R1 and the third recess R3 in a plan view is designed to be equal, the volume of each recess will not be the same. On the other hand, in the physical quantity sensor 1 of this embodiment, it is assumed that the first recess R1, the second recess R2, and the third recess R3 are all etched together using photolithography so that they have the same depth. Therefore, in the configuration example shown in Figure 1 where the third recess R3 is not divided, if the processing of the first recess R1 and the third recess R3 is performed together, the non-uniformity in the direction along the first direction DR1 of the moment of inertia I of the movable body MB cannot be eliminated. Thus, the accuracy of detecting the physical quantity will not be sufficiently improved.

[0051] In this regard, 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 in plan view, the etching rate of the first recess R1 and the etching rate of the third recess R3 can be optimized to be close, and each recess can be processed to the same depth in a single process under the same etching conditions. Specifically, if the etching rate of the third recess R3 is slower than the etching rate of the first recess R1, for example, the etching rate can be increased by lowering the aspect ratio of the third recess R3 by widening the width of each segmented recess in the first direction in a plan view of the third direction DR3. It is also thought that the etching rate can be adjusted by adjusting the spacing between each segmented recess of the third recess R3. Note that in the first detailed example, the third recess R3 is divided into four parts, but the number of divisions may be increased or decreased.

[0052] As described above, according to this embodiment, the third recess R3 can be divided into multiple segmented recesses. In this way, by adjusting the pattern of the third recess R3, it becomes possible to adjust the etching rates of the first recess R1 and the third recess R3 to be closer. Therefore, the first recess R1 and the third recess R3 can be machined to the same depth in a single process. Thus, the non-uniformity of the moment of inertia I in the first direction DR1 of the movable body MB can be eliminated with a simpler process, and the accuracy of detecting physical quantities can be improved. However, if the depth of each segmented recess is machined to penetrate the second portion 32 of the frame portion 30, the rigidity of the frame portion 30 may deteriorate. In this case, the frame portion 30 itself may become more prone to twisting, and problems may occur when high-frequency vibrations are applied.

[0053] Furthermore, in the first detailed example, the width of the divided recess in the first direction DR1 can be made the same as the width of each movable electrode 21 of the first movable electrode group 20A in the first direction DR1. In this way, for example, if the first recess R1 in Figure 8 is composed of four rectangular shapes, providing four divided recesses of the same width in the third recess will eliminate the non-uniformity of mass of the movable body MB in the first direction DR1.

[0054] Furthermore, in the first detailed example, the total area of ​​the multiple divided recesses can be made the same as the area of ​​the first recess R1 in a plan view in the third direction DR3. As described above, according to the first detailed example, the etching rate of the third recess can be adjusted by changing the pattern of the third recess in a plan view in the third direction DR3, thereby bringing the etching rates of the first recess R1 and the third recess R3 closer together. Therefore, if the total area of ​​the multiple divided recesses of the third recess R3 and the area of ​​the first recess R1 are the same in a plan view in the third direction DR3, then by processing each recess so that its depth is equal, the volume of each recess will be equal. Consequently, the volume of the first recess R1 and the volume of the third recess R3 can be made the same in a single etching process. Thus, the effect of improving the detection sensitivity of the physical quantity of the physical quantity sensor 1 can be achieved with a simpler and lower-cost manufacturing process.

[0055] 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 the first detailed example shown in Figure 8, the area of ​​the first recess R1, which is shaded, may extend over the entire comb-shaped movable electrode 21.

[0056] As described above, the physical quantity sensor 1 of this embodiment detects a physical quantity by detecting a change in the opposing area between the fixed electrode 14 and the movable electrode 24 as a change in capacitance. Therefore, by providing a wide area for the first recess R1 as in this embodiment, a wider opposing area between the fixed electrode 11 and the movable electrode 21 can be secured. Consequently, acceleration can be detected as a larger change in capacitance, improving the detection sensitivity of the physical quantity sensor 1. The above configuration can also be applied to the detection unit ZB. For example, the area of ​​the second recess R2, which is shaded in Figure 8, may be extended to the entire fixed electrode 12. In this way, a wider opposing area between the fixed electrode 12 and the movable electrode 22 can be secured in the detection unit ZB as well, and acceleration can be detected as a larger change in capacitance.

[0057] Figure 9 is a plan view of a second detailed example of this embodiment. The configuration of the first detection element 100 differs from the configuration example in Figure 1 and the first detailed example in Figure 8. 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 are provided with a fixing section 40 as a common anchor, with the first element section 91 on the side of the second direction DR2 and the second element section 92 on the side opposite to the second direction DR2. Each element section is provided with detection sections ZA and ZB corresponding to the N side and P side, respectively, enabling the detection of physical quantities in the third direction DR3.

[0058] The first element section 91 has the same configuration as the first detection element 100 in the configuration example and the first detailed example in Figure 1. The second element section 92 is Includes a first fixed electrode group 50A and a second fixed electrode group 50B It includes a fixed electrode section 50, a second movable body MB2, and support beams 82 and 83. Here, in the second detailed example, in order to distinguish the movable body of the first element section 91 from the movable body of the second element section 92, the movable body of the first element section 91 is described as the first movable body MB1. Second movable body MB2 This is the first movable electrode group 60A It includes a movable electrode section 60 having a second movable electrode group 60B, and a frame section 70.

[0059] 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. The fixed electrode section 10 is provided with a second fixed electrode group 10B corresponding to the P side and a first fixed electrode group 10A corresponding to the N side, with each electrode group having fixed electrodes 12 and 11, respectively. Similarly, the fixed electrode section 50 is provided with a second fixed electrode group 50B corresponding to the P side and a first fixed electrode group 50A corresponding to the N side, with each electrode group having fixed electrodes 52 and 51, respectively.

[0060] 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. 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, and each electrode group has 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, and each electrode group has movable electrodes 62 and 61, respectively. The movable electrodes 21 and 22 extend from the second portion 32 of the frame section 30 and are arranged to face the fixed electrodes 11 and 12. The movable electrodes 61 and 62 extend from the second portion 72 of the frame section 70 and are arranged to face the fixed electrodes 51 and 52. Furthermore, similar to the configuration examples shown in Figures 1 and 8, 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 configuration, the second detailed example can detect acceleration in the third direction DR3 in both the first element section 91 and the second element section 92.

[0061] Furthermore, the first movable electrode group 60A of the second element section 92 is provided with a first recess R4, the second fixed electrode group 50B is provided with a second recess R5, and the second portion 72 of the frame section 70 is provided with a third recess R6. The first recess R4, second recess R5, and third recess R6 of the second element section 92 correspond to the first recess R1, second recess R2, and third recess R3 of the first element section 91, respectively.

[0062] Thus, the second element section 92 is also provided with a first recess R4 and a third recess R6 corresponding to the first recess R1 and third recess R3 of the first element section 91, thereby eliminating the non-uniformity of the mass of the second movable body MB2. Therefore, while reducing cross-axial sensitivity in each element section and achieving high-precision detection of physical quantities, the detection sensitivity is also improved by providing two element sections. Furthermore, unwanted vibrations caused by external vibrations and shocks can be avoided, providing a reliable physical quantity sensor 1 with long-term reliability.

[0063] Figure 10 is a plan view of a modified example of the second detailed example of this embodiment. The pattern of the third recess in plan view differs from that of the second detailed example. Specifically, the pattern of the third recess R3 in the second detailed example is a plurality of rectangular divided recesses with the first direction DR1 as the longitudinal direction in this modified example. Even if the third recess R3 is provided as in this embodiment, the effects of having multiple divided recesses as described above can be obtained.

[0064] In this embodiment, the movable body MB may include a first portion 31, one end of which is connected to the other end of the support beams 42 and 43 and which extends with the second direction as the long side direction, and a second portion 32, one end of which is connected to the first portion 31 and which extends with the first direction DR1 as the long side direction.

[0065] In this way, a roughly U-shaped movable body MB can be constructed in the physical quantity sensor 1 shown in Figure 1, etc. Then, as described above, the movable body MB can perform rotational motion with the first direction DR1 as the axis of rotation via the support beams 42 and 43, and the physical quantity sensor 1 can detect acceleration in the third direction DR3.

[0066] In this embodiment, the movable electrode portion 20 is connected to the second portion 32.

[0067] In this way, the movable electrode section 20 can move in conjunction with the second section 32 of the frame section 30. Therefore, the physical quantity sensor 1 can detect acceleration in the third direction DR3 by the movement of the movable body MB with the first direction DR1 as the axis of rotation.

[0068] 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 30. Consequently, the non-uniformity of mass along the first direction DR1 of the movable body MB caused by the provision of the first recess R1 is eliminated, and the detection accuracy of the physical quantity sensor 1 is improved.

[0069] 3. Inertial measurement device Next, an example of the inertial measurement device 2000 of this embodiment will be described using Figures 11 and 12. The inertial measurement device 2000 (IMU) shown in Figure 11 is a device that detects inertial momentum such as the attitude and behavior of a moving object such as an automobile or a robot. The inertial measurement device 2000 is a so-called 6-axis motion sensor equipped with acceleration sensors that detect accelerations ax, ay, and az in the direction along three axes, and angular velocity sensors that detect angular velocities ωx, ωy, and ωz around three axes.

[0070] The inertial measuring device 2000 is a rectangular prism with a roughly square shape in plan view. Screw holes 2110, which serve as mounting points, are formed near two vertices located diagonally across the square. The inertial measuring device 2000 can be fixed to the mounting surface of an object such as an automobile by passing two screws through these two screw holes 2110. Furthermore, by selecting components and modifying the design, it is possible to miniaturize the device to a size that can be mounted on, for example, a smartphone or digital camera.

[0071] The inertial measuring device 2000 comprises an outer case 2100, a connecting member 2200, and a sensor module 2300. The sensor module 2300 is inserted into the outer case 2100 with the connecting member 2200 interposed between them. The sensor module 2300 comprises an inner case 2310 and a circuit board 2320. The inner case 2310 has a recess 2311 to prevent contact with the circuit board 2320 and an opening 2312 to expose a connector 2330, which will be described later. The circuit board 2320 is bonded to the lower surface of the inner case 2310 via adhesive.

[0072] As shown in Figure 12, the top surface of the circuit board 2320 is equipped with a connector 2330, an angular velocity sensor 2340z for detecting angular velocity around the Z axis, and an acceleration sensor unit 2350 for detecting acceleration in the X, Y, and Z axes. Additionally, the sides of the circuit board 2320 are equipped with an angular velocity sensor 2340x for detecting angular velocity around the X axis and an angular velocity sensor 2340y for detecting angular velocity around the Y axis.

[0073] The acceleration sensor unit 2350 includes at least the physical quantity sensor 1 for measuring acceleration in the Z-axis direction as described above, and can detect acceleration in one axis direction, or acceleration in two or three axes as needed. The angular velocity sensors 2340x, 2340y, and 2340z are not particularly limited, but for example, a vibration gyro sensor utilizing the Coriolis force can be used.

[0074] Furthermore, a control IC 2360 is mounted on the underside of the circuit board 2320. The control IC 2360, which acts as a control unit that performs control based on the detection signal output from the physical quantity sensor 1, is, for example, an MCU (Micro Controller Unit), and incorporates a storage unit including non-volatile memory and an A / D converter, and controls various parts of the inertial measurement device 2000. In addition, several other electronic components are mounted on the circuit board 2320.

[0075] As described above, the inertial measurement device 2000 of this embodiment includes a physical quantity sensor 1 and a control IC 2360 which acts as a control unit that performs control based on the detection signal output from the physical quantity sensor 1. With this inertial measurement device 2000, since an acceleration sensor unit 2350 including the physical quantity sensor 1 is used, the effects of the physical quantity sensor 1 can be enjoyed, and an inertial measurement device 2000 that can achieve high accuracy and the like can be provided.

[0076] The inertial measurement device 2000 is not limited to the configurations shown in Figures 11 and 12. For example, the inertial measurement device 2000 may be configured to include only the physical quantity sensor 1 as an inertial sensor, without the angular velocity sensors 2340x, 2340y, and 2340z. In this case, the inertial measurement device 2000 can be realized by housing the physical quantity sensor 1 and the control IC 2360, which implements the control unit, in a package that serves as a housing.

[0077] 4. Manufacturing method Finally, the manufacturing method of this embodiment will be described. Figure 13 is a plan view of the physical quantity sensor 1 of this embodiment shown in Figure 1. In the following explanation, Figures 14 to 21 will describe the manufacturing method of this embodiment using a cross-sectional view along the dashed line connecting B and B' in the plan view shown in Figure 13.

[0078] First, as shown in Figure 14, prepare a silicon substrate 200 and apply a surface oxide film 204 to it. μ After forming a layer of approximately m, patterning is performed using photolithography. After partially removing the surface oxide film 204 using wet etching such as BHF (Buffered Hydrogen Fluoride), the layer is then etched to a depth of 20-50 μ Etching is performed on a silicon substrate 200 of approximately m in thickness. This etching can be done by wet etching using KOH or TMAH, or by dry etching using SF6 gas. Alternatively, deep silicon etching using the BOSCH process with alternating SF6 and C4F8 is also acceptable. This forms a cavity 202. The unwanted surface oxide film 204 may be removed or left on.

[0079] Next, as shown in Figure 15, the silicon substrate 200 is bonded to the silicon substrate wafer 208, which will serve as the structural layer. During bonding, an embedded insulating film 206 is formed on the silicon substrate, followed by plasma activation with Ar, N2, etc., and then a water washing treatment before bonding. Furthermore, after bonding, an annealing treatment at 500-1100°C may be performed to enhance strength. At this time, some embedded insulating film 206 may remain at the bottom of the cavity 202. After bonding, the wafer 208 is ground for 20-30°C. μ A structural layer with a thickness of approximately m is formed. The wafer 208 can be ground using processes such as CMP (Chemical Mechanical Polishing). Then, as shown in Figure 16, a hard mask SiO2 layer 210 is deposited on the structural layer. The SiO2 layer 210 can be deposited by thermal oxidation, CVD (Chemical Vapor Deposition), SOG (Spin On-Glass), etc. In particular, the SiO2 layer 210 deposited by thermal oxidation is preferable because it has a high selectivity ratio during silicon etching. In this manufacturing method, 1 μ A thermal oxide film of approximately m is used.

[0080] Next, as shown in Figure 17, patterning is performed by photolithography, and the thickness of the SiO2 layer 210 in the area where the first recess R1 is provided 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 with BHF or the like is preferable. Then, as shown in Figure 18, a photoresist 214 is deposited, and the outer shape of each element part of the physical quantity sensor 1 is patterned. Then, the SiO2 layer 210 is processed by dry etching or the like. For dry etching, for example, CHF3 gas can be used.

[0081] Next, as shown in Figure 19, the unnecessary photoresist 214 is removed by ashing or the like, and the wafer 208 that will become the structural layer is etched using, for example, the BOSCH method. Here, the depth of etching is such that only h1 remains from the outermost layer of the embedded insulating film 206. Then, as shown in Figure 20, the entire SiO2 layer 210 deposited as a hard mask is etched so that the silicon structural layer in the area where the first recess R1 will be made is exposed. Note that this etching method can be either dry etching or wet etching. Then, as shown in Figure 21, when the entire silicon structural layer is etched, the first recess R1 becomes a step with a depth of h1, and the other parts are processed to the bottom and become penetrated. Finally, as shown in Figure 22, the unnecessary hard mask is removed.

[0082] Furthermore, in the regions where the second recess R2 and third recess R3 are provided, recesses are formed in a third direction DR3 within a part of the structural layer, similar to the first recess R1. Therefore, the second recess R2 and third recess R3 can be provided by patterning the regions where the second recess R2 and third recess R3 are provided on the SiO2 layer 210 of the hard mask and etching the wafer 208 which will become the structural layer.

[0083] As described above, the manufacturing method of this embodiment is a method for manufacturing a physical quantity sensor 1 that detects a physical quantity in 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, and includes a fixed electrode part forming step of forming a fixed electrode part 10 on a substrate 2, and a movable body forming step of forming a movable body MB. The physical quantity sensor 1 includes a fixed part 40 fixed to the substrate 2, support beams 42 and 43 each have one end connected to the fixed part 40, and the fixed electrode part 10 is provided on the substrate 2 and includes a first fixed electrode group 10A and a second fixed electrode group 10B. The movable body MB includes a movable electrode section 20 in which a first movable electrode group 20A is provided, where each movable electrode 21 faces each fixed electrode 11 of the first fixed electrode group 10A, and a second movable electrode group 20B is provided, where each movable electrode 22 faces each fixed electrode 12 of the second fixed electrode group 10B, and a frame section 30 that connects the movable electrode section 20 to the other ends of the support beams 42 and 43. In the fixed electrode section formation step, the second fixed electrode group 10B is formed such that a second recess R2 is provided in the second fixed electrode group 10B which is recessed in the third direction DR3. In the movable body formation step, the first movable electrode group 20A is formed such that a first recess R1 is provided in the first movable electrode group 20A which is recessed in the third direction, and the movable body MB is formed in the region of the frame section 30 on the second movable electrode group 20B side such that a third recess R3 is provided which is recessed in the third direction DR3.

[0084] In the physical quantity sensor 1 of this embodiment, in order to ensure the mobility of the movable body MB, a certain space is provided inside the first detection element 100 of the physical quantity sensor 1, and each component such as the movable body MB, the fixed electrode part 10, and the support beams 42 and 43 must be formed and arranged with high precision within this space. Furthermore, in order to eliminate the non-uniformity of the mass of the movable body MB, a configuration is adopted in which the first recess R1, the second recess R2, and the third recess R3 are provided, but as mentioned above, there is also a need to process these all at once.

[0085] In this respect, according to this embodiment, as explained in Figure 15, the space inside the first detection element 100 can be created using the wafer bonding process after the formation of the cavity 202. Therefore, the complexity of processes such as removing a deposited sacrificial film by wet etching can be avoided, and the difficulty of the process can be reduced. When processing by dry etching, problems such as surface roughness and reduced yield can occur, but these problems can also be avoided. Furthermore, as mentioned above, by adjusting the pattern of the third recess R3 in plan view and optimizing the etching rate of the third recess R3, it becomes possible to process each recess at once, thereby streamlining the manufacturing process and reducing costs.

[0086] As described above, the physical quantity sensor of this embodiment detects a physical quantity in the third direction when the mutually orthogonal directions are defined as the first direction, second direction, and third direction. A fixed electrode portion provided on the substrate, This relates to a physical quantity sensor that includes a fixed part fixed to a substrate, a support beam with one end connected to the fixed part, and a movable body. , movable electrode part and The device comprises a frame section that connects the movable electrode section to the other end of the support beam. The fixed electrode section is provided with a first fixed electrode group and a second fixed electrode group. The movable electrode section is provided with a first movable electrode group, each of which movable electrodes faces the fixed electrode of the first fixed electrode group, and a second movable electrode group, each of which movable electrodes faces the fixed electrode of the second fixed electrode group. The frame section connects the movable electrode section to the other end of the support beam. The first movable electrode group is provided with a first recess that is recessed in the third direction, the second fixed electrode group is provided with a second recess that is recessed in the third direction, and the region of the frame section on the side of the second movable electrode group is provided with a third recess that is recessed in the third direction.

[0087] According to this embodiment, the non-uniformity of the mass of the movable body of the physical quantity sensor on the axis in the first direction is eliminated, and the center of gravity of the physical quantity sensor does not shift. Therefore, the sensitivity of the physical quantity sensor on other axes can be reduced, and the detection accuracy of the physical quantity can be improved. In addition, unwanted vibrations are less likely to occur due to external vibrations and shocks, and a good physical quantity sensor with high long-term reliability can be provided.

[0088] In this embodiment, the first recess and the third recess may have the same area in a plan view in the third direction.

[0089] By doing so, the depths of the first recess and the third recess are made equal, eliminating the non-uniformity of the moment of inertia in the first direction with the first direction as the axis of rotation. Consequently, the detection accuracy of the physical quantity sensor can be improved.

[0090] In this embodiment, the first recess and the third recess may have the same depth in the third direction.

[0091] In this way, by making the area of ​​the first recess and the third recess the same in a plan view in the third direction, the volumes of the first recess and the third recess can be made equal. Therefore, the non-uniformity of the moment of inertia in the first direction DR1 with the first direction as the axis of rotation can be eliminated, and the detection accuracy of the physical quantity sensor can be improved.

[0092] In this embodiment, the first recess and the third recess may have the same volume.

[0093] In this way, the non-uniformity of the first direction DR1 of the moment of inertia I with the first direction as the axis of rotation can be eliminated, and the detection accuracy of the physical quantity of the physical quantity sensor 1 can be improved.

[0094] In this embodiment, the third recess may be divided into a plurality of segmented recesses.

[0095] In this way, the third recess can be divided into multiple segmented recesses. Therefore, by adjusting the pattern of the third recess, it becomes possible to adjust the etching rates of the first and third recesses to be similar. Consequently, the first and third recesses can be machined to the same depth in a single process. Thus, the non-uniformity of the moment of inertia of the movable body MB in the first direction can be eliminated with a simpler process, and the accuracy of detecting physical quantities can be improved.

[0096] In this embodiment, the width of the divided recess in the first direction may be the same as the width of each movable electrode in the first movable electrode group in the first direction.

[0097] In this way, if the first recess is composed of multiple rectangular shapes, the non-uniformity of mass in the first direction of the movable body can be eliminated by providing the same number of divided recesses of the same width in the third recess.

[0098] In this embodiment, the total area of ​​the multiple divided recesses may be the same as the area of ​​the first recess in a plan view in the third direction.

[0099] In this way, by adjusting the pattern of the divided recesses in the third direction and bringing the etching rates of the first and third recesses closer together, the volumes of the first and third recesses can be made identical through batch processing. Therefore, an improvement in the detection sensitivity of physical quantities in physical quantity sensors can be achieved with a simpler and lower-cost manufacturing process.

[0100] In this embodiment, the length of the first recess in the second direction may be the same as the length of each movable electrode in the second direction of the first movable electrode group.

[0101] This approach allows for a larger surface area between the fixed and movable electrodes, enabling the detection of acceleration as a larger change in capacitance. Consequently, the detection sensitivity of the physical quantity sensor is improved.

[0102] In this embodiment, the movable body includes a first portion, one end of which is connected to the other end of the support beam and extending with the second direction as the long side direction, and a second portion, one end of which is connected to the first portion and extending with the first direction as the long side direction.

[0103] In this way, a movable body roughly shaped like a U can be constructed. The movable body can then perform motion with the first direction as its axis of rotation via the support beams 42 and 43, and the physical quantity sensor can detect acceleration in the third direction.

[0104] In this embodiment, the movable electrode portion is connected to the second portion.

[0105] In this way, the movable electrode can swing together with the second part of the frame. Therefore, the physical quantity sensor can detect acceleration in a third direction by the motion of the movable body with the first direction as the axis of rotation.

[0106] In this embodiment, the third recess is provided in the second portion.

[0107] In this way, the volume of a portion of the second part of the frame can be reduced. Consequently, the non-uniformity of mass along the first direction of the movable body caused by the provision of the first recess can be eliminated, and the detection accuracy of the physical quantity by the physical quantity sensor can be improved.

[0108] Furthermore, this embodiment, As described above, physical quantity sensors and This relates to an inertial measuring device that includes a control unit that performs control based on detection signals output from a physical quantity sensor.

[0109] Furthermore, the manufacturing method of this embodiment relates to a manufacturing method that includes a fixed electrode portion formation step of forming a fixed electrode portion on a substrate of a physical quantity sensor that detects a physical quantity in the third direction, when three mutually orthogonal directions are designated as the first direction, second direction, and third direction, and a movable body formation step of forming a movable body. The physical quantity sensor includes a fixed portion fixed to the substrate, the support beam has one end connected to the fixed portion, and the fixed electrode portion is provided on the substrate and includes a first fixed electrode group and a second fixed electrode group. The movable body includes a movable electrode portion in which 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, and a frame portion that connects the movable electrode portion and the other end of the support beam. In the fixed electrode portion formation step, the second fixed electrode group is formed such that the second fixed electrode group is provided with a second recess that is recessed in the third direction. In the movable body formation process, the first movable electrode group is formed such that it has a first recess that is recessed in a third direction, and the movable body is formed in the region of the frame portion on the side of the second movable electrode group such that it has a third recess that is recessed in a third direction.

[0110] 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 in a plan view and optimizing the etching rate of the third recess, it becomes possible to process each recess simultaneously. Therefore, rationalization of the manufacturing process and cost reduction can be achieved.

[0111] Although this embodiment has been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novelty and effects of this disclosure. Therefore, all such modifications are included within the scope of this disclosure. For example, any term that appears at least once in the specification or drawings together with a 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 also included within the scope of this disclosure. In addition, the configuration and operation of the physical quantity sensor, inertial measuring device, and manufacturing method are not limited to those described in this embodiment, and various modifications are possible. [Explanation of Symbols]

[0112] 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…Movable electrode section, 20A…First movable electrode group, 20B…Second movable electrode group, 21…Movable electrode, 22…Movable electrode, 24…Movable electrode, 30…Frame section, 31…First part, 32…Second part, 40…Fixed section, 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 section, 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 oxide film, 206...Embedded insulation Film, 208...wafer, 210...SiO2 layer, 214...photoresist, 2000...inertial measurement device, 2100...outer case, 2110...screw hole, 2200...bonding member, 2300...sensor module, 2310...inner case, 2311...recess, 2312...opening, 2320...circuit board, 2330...connector, 2340x...angular velocity sensor, 2340y...angular velocity sensor, 2340z...angular velocity sensor, 235 0...Accelerometer 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...Moment of inertia, IC2360...Control, LFA...Wiring, LFB...Wiring, LV...Wiring, MB...Moveable 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 recess, R3...third recess, R4...first recess, R5...second recess, R6...third recess, Z...detection unit, ZA...detection unit, ZB...detection unit, ax...acceleration, ay...acceleration, az...acceleration, h1...depth, ωx...angular velocity

Claims

1. When mutually orthogonal directions are defined as the first direction, second direction, and third direction, a physical quantity sensor detects a physical quantity in the third direction, The fixing part is fixed to the circuit board, A support beam, one end of which is connected to the fixed part, A fixed electrode section is provided on the substrate and includes a first fixed electrode group and a second fixed electrode group, A movable body including a movable electrode section containing a first movable electrode group and a second movable electrode group, and a frame section connecting the movable electrode section and the other end of the support beam, Includes, The XL1 fixed electrode group includes a first fixed electrode, The second fixed electrode group includes the second fixed electrode, The first movable electrode group described above includes the first movable electrode, The aforementioned second movable electrode group includes the second movable electrode, The first fixed electrode faces the first movable electrode, The second fixed electrode faces the second movable electrode, The first movable electrode is provided with a first recess that is recessed in the third direction, The second fixed electrode is provided with a second recess that is recessed in the third direction, The aforementioned movable body is One end of the first portion is connected to the other end of the support beam and is arranged along the second direction, A second portion is connected to one end of the first portion and is arranged along the first direction, Includes, The movable electrode portion is connected to the second portion, A third recess is provided in the region of the second portion of the frame that is on the side of the second movable electrode group, which is recessed in the third direction. A physical quantity sensor characterized in that the physical quantity is detected by the capacitance between the first fixed electrode and the first movable electrode, and the capacitance between the second fixed electrode and the second movable electrode.

2. In the physical quantity sensor according to claim 1, A physical quantity sensor characterized in that, in a plan view from the third direction, the area of ​​the first recess and the area of ​​the third recess are the same.

3. In the physical quantity sensor according to claim 2, A physical quantity sensor characterized in that the depth of the first recess in the third direction and the depth of the third recess in the third direction are the same.

4. In the physical quantity sensor according to claim 1, The volume of the first recess and the volume of the third recess are the same, which is a characteristic of the physical quantity sensor. Sir.

5. In the physical quantity sensor according to claim 3 or 4, The physical quantity sensor is characterized in that the third recess is divided into a plurality of segmented recesses.

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

7. In the physical quantity sensor according to claim 5 or 6, A physical quantity sensor characterized in that, in a plan view in the third direction, the total area of ​​the plurality of divided recesses is the same as the area of ​​the first recess.

8. In a physical quantity sensor according to any one of claims 1 to 7, A physical quantity sensor 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. A physical quantity sensor according to any one of claims 1 to 8, A control unit that performs control based on the detection signal output from the physical quantity sensor, An inertial measuring device characterized by including [a certain element].

10. A method for manufacturing a physical quantity sensor that detects a physical quantity in the third direction, where three mutually orthogonal directions are designated as the first direction, the second direction, and the third direction, A fixed electrode portion formation step in which a fixed electrode portion is formed on a substrate, A movable body forming process, Includes, The aforementioned physical quantity sensor is Including the fixing part fixed to the substrate, The support beam has one end connected to the fixed part, The aforementioned fixed electrode portion is Provided on the substrate, It includes a first fixed electrode group and a second fixed electrode group, The aforementioned movable body is A movable electrode section including a first movable electrode group and a second movable electrode group, A frame portion connecting the movable electrode portion and the other end of the support beam, Includes, The XL1 fixed electrode group includes a first fixed electrode, The second fixed electrode group includes the second fixed electrode, The first movable electrode group described above includes the first movable electrode, The aforementioned second movable electrode group includes the second movable electrode, The first fixed electrode faces the first movable electrode, The second fixed electrode faces the second movable electrode, The aforementioned movable body is One end of the first portion is connected to the other end of the support beam and is arranged along the second direction, A second portion is connected to one end of the first portion and is arranged along the first direction, Includes, The movable electrode portion is connected to the second portion, The physical quantity is detected by the capacitance between the first fixed electrode and the first movable electrode, and the capacitance between the second fixed electrode and the second movable electrode. In the aforementioned fixed electrode formation step, The second fixed electrode group is formed such that the second fixed electrode has a second recess that is recessed in the third direction. In the aforementioned movable body forming step, The first movable electrode group is formed such that the first movable electrode has a first recess that is recessed in the third direction. A manufacturing method characterized in that the movable body is formed such that a third recess that is recessed in the third direction is provided in the region of the second portion of the frame on the side of the second movable electrode group.

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