JP7099284B2 - Inertia sensors, electronic devices and moving objects - Google Patents

Description

The present invention relates to inertial sensors, electronic devices and moving objects.

The angular velocity sensor described in Patent Document 1 includes a movable drive electrode, a fixed drive electrode that vibrates the movable drive electrode, a movable detection electrode connected to the movable drive electrode via a vibration amount amplification unit, and a movable detection electrode. And a fixed detection electrode arranged to face each other. In the angular velocity sensor having such a configuration, the movable detection electrode is vibrated in the Y-axis direction together with the movable drive electrode by generating an electrostatic attraction between the movable drive electrode and the fixed drive electrode (this vibration mode is "drive vibration". When an angular velocity around the X-axis is applied in this state, the movable detection electrode vibrates in the Z-axis direction due to the force of the colioli (this vibration mode is called the "detection vibration mode"), and changes accordingly. The angular velocity around the X-axis can be detected based on the capacitance between the movable detection electrode and the fixed detection electrode.

Such an angular velocity sensor can be formed, for example, by using the Bosch process, which is a deep groove etching technique for silicon described in Patent Document 2. In the deep groove etching technique of silicon, two systems of gas, SF ₆ which is an etching gas and gas C ₄ F ₈ for forming a side wall protective film, are alternately switched, and the etching process and the side wall protective film forming process are alternately repeated. This is a technique for forming a deep groove in silicon. According to such a deep groove etching technique, it is possible to form a groove having an excellent verticality of the groove side surface and a high aspect ratio.

Japanese Unexamined Patent Publication No. 2009-175079 Special Table No. 7-503815 Gazette

However, when the deep groove etching technique described in Patent Document 2 is used, for example, depending on the position in the chamber of the wafer to be etched, a through hole is inclined in an oblique direction with respect to the normal direction of the etching surface of the wafer to be etched. May be formed. If the through hole is formed diagonally in this way, the cross-sectional shape of the vibration amount amplification portion deviates from the rectangle. In this way, if the cross-sectional shape of the vibration amount amplification portion deviates from the rectangle, the movable detection electrode vibrates not only in the Y-axis direction but also in the Z-axis direction in the drive vibration mode, and the angular velocity detection characteristic deteriorates. ..

The vibration (unnecessary vibration) of the movable detection electrode in the drive vibration mode in the Z-axis direction is also called a "quadracha", and the noise signal caused by this quadracha is also called a "quadracha signal". There is.

In the inertial sensor of the present invention, when the three axes orthogonal to each other are the X-axis, the Y-axis and the Z-axis,
With the board
A detection movable body that overlaps the substrate in the direction along the Z axis and faces the substrate.
A fixed detection electrode arranged on the substrate and facing the detection movable body, and
It has a drive unit that vibrates the detection movable body, and has
The vibration of the detected movable body has a drive vibration mode in which vibration in the direction along the X axis and vibration in the direction along the Z axis are combined.
In a plan view from the Z-axis direction
When the line that bisects the detected movable body in the direction along the X axis is used as the center line,
The center of gravity of the detected movable body is deviated from the center line in the direction along the X axis.
The distance between the center of gravity and the center line is smaller than the amplitude of the detected movable body in the direction along the X axis.

It is a top view which shows the inertia sensor which concerns on 1st Embodiment. FIG. 3 is a sectional view taken along line AA in FIG. It is a top view which shows the sensor element which the inertia sensor of FIG. 1 has. It is a figure which shows the voltage applied to the inertia sensor of FIG. FIG. 3 is a sectional view taken along line BB in FIG. 3 showing a drive vibration mode of the sensor element. It is a top view which shows the movable detection electrode which a sensor element has. It is sectional drawing of the movable detection electrode shown in FIG. It is sectional drawing which shows the drive vibration mode of a sensor element. It is a model diagram which shows the conventional structure. It is a model diagram which shows this embodiment. It is a figure which shows the manufacturing process of the inertia sensor of FIG. It is sectional drawing for demonstrating the manufacturing method of the inertia sensor of FIG. It is sectional drawing for demonstrating the manufacturing method of the inertia sensor of FIG. It is sectional drawing for demonstrating the manufacturing method of the inertia sensor of FIG. It is sectional drawing for demonstrating the manufacturing method of the inertia sensor of FIG. It is sectional drawing for demonstrating another manufacturing method of an inertia sensor. It is sectional drawing for demonstrating another manufacturing method of an inertia sensor. It is sectional drawing for demonstrating another manufacturing method of an inertia sensor. It is sectional drawing which shows the inertia sensor which concerns on 2nd Embodiment. It is sectional drawing which shows the inertia sensor which concerns on 3rd Embodiment. It is a top view which shows the smartphone as an electronic device which concerns on 4th Embodiment. It is an exploded perspective view which shows the inertial measurement unit as an electronic device which concerns on 5th Embodiment. FIG. 22 is a perspective view of a substrate included in the inertial measurement unit shown in FIG. 22. It is a block diagram which shows the whole system of the mobile positioning apparatus as an electronic device which concerns on 6th Embodiment. It is a figure which shows the operation of the mobile body positioning apparatus shown in FIG. 24. It is a perspective view which shows the moving body which concerns on 7th Embodiment.

Hereinafter, the inertial sensor, the electronic device, and the moving body of the present invention will be described in detail based on the embodiments shown in the accompanying drawings.

<First Embodiment>
FIG. 1 is a plan view showing an inertial sensor according to the first embodiment. FIG. 2 is a cross-sectional view taken along the line AA in FIG. FIG. 3 is a plan view showing a sensor element included in the inertial sensor of FIG. FIG. 4 is a diagram showing a voltage applied to the inertial sensor of FIG. FIG. 5 is a sectional view taken along line BB in FIG. 3 and is a diagram showing a drive vibration mode of the sensor element. FIG. 6 is a plan view showing a movable detection electrode included in the sensor element. FIG. 7 is a cross-sectional view of the movable detection electrode shown in FIG. FIG. 8 is a cross-sectional view showing a drive vibration mode of the sensor element. FIG. 9 is a model diagram showing a conventional configuration. FIG. 10 is a model diagram showing the present embodiment. FIG. 11 is a diagram showing a manufacturing process of the inertial sensor of FIG. 12 to 15 are sectional views for explaining a method of manufacturing the inertial sensor of FIG. 1, respectively. 16 to 18 are sectional views for explaining another manufacturing method of the inertial sensor, respectively.

In each figure, an X-axis, a Y-axis, and a Z-axis are shown as three axes orthogonal to each other. Further, the direction along the X-axis, that is, the direction parallel to the X-axis is also referred to as "X-axis direction", the direction along the Y-axis is referred to as "Y-axis direction", and the direction along the Z-axis is also referred to as "Z-axis direction". Further, the arrow tip side of each axis is also referred to as "plus side", and the opposite side is also referred to as "minus side". Further, the plus side in the Z-axis direction is also referred to as "up", and the minus side in the Z-axis direction is also referred to as "down". Further, in the present specification, "orthogonal" includes not only the case where they intersect at 90 ° but also the case where they intersect at an angle slightly inclined from 90 °, for example, within a range of 90 ° ± 5 °.

The inertial sensor 1 shown in FIG. 1 is an angular velocity sensor capable of detecting an angular velocity ωy around the Y axis. The inertial sensor 1 has a substrate 2, a lid 3, and a sensor element 4.

The substrate 2 has a recess 21 that opens to the upper surface. The recess 21 functions as a relief portion for preventing contact between the sensor element 4 and the substrate 2. Further, the substrate 2 has a plurality of mounts 221, 222, 224 protruding from the bottom surface of the recess 21. The sensor element 4 is bonded to the upper surfaces of the mounts 221, 222, and 224.

Further, fixed detection electrodes 71 and 72 are arranged on the bottom surface of the recess 21. Further, the substrate 2 has a groove opened on the upper surface, and wirings 73, 74, 75, 76, 77, and 78 are arranged in this groove. Further, one end of the wiring 73, 74, 75, 76, 77, 78 is exposed to the outside of the lid 3, and functions as an electrode pad P for electrical connection with an external device.

Such a substrate 2 is made of, for example, a glass material containing an alkali metal ion such as sodium ion, specifically, borosilicate glass such as Tempax glass (registered trademark) and Pylex glass (registered trademark). A glass substrate can be used. However, the constituent material of the substrate 2 is not particularly limited, and a silicon substrate, a ceramic substrate, or the like may be used.

As shown in FIG. 2, the lid 3 has a recess 31 that opens to the lower surface. The lid 3 is joined to the upper surface of the substrate 2 so that the sensor element 4 is housed in the recess 31. A storage space S for accommodating the sensor element 4 is formed inside the lid 3 and the substrate 2. The storage space S is preferably in a reduced pressure state, particularly preferably in a vacuum state. As a result, the viscous resistance is reduced, and the sensor element 4 can be vibrated efficiently.

As such a lid 3, for example, a silicon substrate can be used. However, the lid 3 is not particularly limited, and for example, a glass substrate or a ceramic substrate may be used. The method of joining the substrate 2 and the lid 3 is not particularly limited and may be appropriately selected depending on the material of the substrate 2 and the lid 3. For example, the bonding surfaces activated by anode bonding or plasma irradiation may be selected. Examples thereof include activated bonding for bonding, bonding with a bonding member such as a glass frit, and diffusion bonding for bonding metal films formed on the upper surface of the substrate 2 and the lower surface of the lid 3. In the present embodiment, the substrate 2 and the lid 3 are bonded to each other via a glass frit 39 which is a low melting point glass.

The sensor element 4 is arranged in the storage space S and is joined to the upper surface of each mount 221, 222, 224. The sensor element 4 is formed by, for example, patterning a conductive silicon substrate doped with impurities such as phosphorus (P), boron (B), and arsenic (As) by the Bosch process, which is a deep groove etching technique. There is.

Hereinafter, the configuration of the sensor element 4 will be described with reference to FIG. In the following, a straight line that intersects the center O of the sensor element 4 and extends in the Y-axis direction in a plan view from the Z-axis direction is also referred to as a “virtual straight line α”.

As shown in FIG. 3, the shape of the sensor element 4 is symmetrical with respect to the virtual straight line α. Such a sensor element 4 has two drive units 41A and 41B arranged on both sides of the virtual straight line α. The drive unit 41A has a comb-shaped movable drive electrode 411A and a fixed drive electrode 412A that is comb-shaped and is arranged so as to mesh with the movable drive electrode 411A. Similarly, the drive unit 41B has a comb-shaped movable drive electrode 411B and a fixed drive electrode 412B which is comb-shaped and is arranged so as to mesh with the movable drive electrode 411B.

Further, the fixed drive electrodes 412A and 412B are respectively bonded to the upper surface of the mount 221 and fixed to the substrate 2. Further, the fixed drive electrodes 412A and 412B are electrically connected to the wiring 74, respectively.

Further, the sensor element 4 has four fixed portions 42A arranged around the drive unit 41A and four fixed portions 42B arranged around the drive unit 41B. The fixing portions 42A and 42B are joined to the upper surface of the mount 222 and fixed to the substrate 2. Further, the sensor element 4 has four drive springs 43A that connect each fixed portion 42A and the movable drive electrode 411A, and four drive springs 43B that connect each fixed portion 42B and the movable drive electrode 411B.

Further, the sensor element 4 has a detection unit 44A located between the drive unit 41A and the virtual straight line α, and a detection unit 44B located between the drive unit 41B and the virtual straight line α. The detection unit 44A is composed of a plate-shaped movable detection electrode 441A which is a detection movable body. Similarly, the detection unit 44B is composed of a movable detection electrode 441B which is a plate-shaped movable detection movable body. Further, on the bottom surface of the recess 21, a fixed detection electrode 71 facing the movable detection electrode 441A and electrically connected to the wiring 75, and a fixed fixing electrode 71 facing the movable detection electrode 441B and electrically connected to the wiring 76. The detection electrode 72 and the like are arranged. When the inertial sensor 1 is driven, a capacitance Ca is formed between the movable detection electrode 441A and the fixed detection electrode 71, and a capacitance Cb is formed between the movable detection electrode 441B and the fixed detection electrode 72. To.

Further, the sensor element 4 has a frame 48 located at the center thereof between the detection units 44A and 44B. The frame 48 has an “H” shape and has a defective portion 481 located on the positive side in the Y-axis direction and a defective portion 482 located on the negative side in the Y-axis direction. A fixed portion 451 extending in the Y-axis direction is arranged inside and outside the defective portion 481, and a fixed portion 452 extending in the Y-axis direction is arranged inside and outside the defective portion 482. The fixing portions 451 and 452 are electrically connected to the wiring 73, respectively.

Further, the sensor element 4 includes four detection springs 46A that connect the movable detection electrode 441A and the fixed portions 42A, 451 and 452, and four detection springs that connect the movable detection electrode 441B and the fixed portions 42B, 451 and 452. It has 46B and. Further, the sensor element 4 is located between the movable drive electrode 411A and the movable detection electrode 441A, is located between the beam 47A connecting them, and between the movable drive electrode 411B and the movable detection electrode 441B, and connects them. It has a beam 47B and a beam 47B. In the following, the aggregate of the movable drive electrode 411A, the movable detection electrode 441A and the beam 47A is also referred to as a “movable body 4A”, and the aggregate of the movable drive electrode 411B, the movable detection electrode 441B and the beam 47B is referred to as a “movable body 4B”. Also called.

Further, the sensor element 4 is located between the fixed portion 451 and the frame 48, and is located between the frame spring 488 that connects them, and the frame spring 489 that is located between the fixed portion 452 and the frame 48 and connects them. , Have.

Further, the sensor element 4 has a connection spring 40A for connecting the frame 48 and the movable detection electrode 441A, and a connection spring 40B for connecting the frame 48 and the movable detection electrode 441B. The connection spring 40A supports the movable detection electrode 441A together with the detection spring 46A, and the connection spring 40B supports the movable detection electrode 441B together with the detection spring 46B. By arranging the connection springs 40A and 40B in addition to the detection springs 46A and 46B, the movable detection electrodes 441A and 441B can be supported in a more stable posture, and unnecessary vibration of the movable detection electrodes 441A and 441B can be reduced. Can be done.

For example, when the voltage V1 shown in FIG. 4 is applied to the movable bodies 4A and 4B via the wiring 73 and the voltage V2 shown in FIG. 4 is applied to the fixed drive electrodes 412A and 412B via the wiring 74, it acts between them. Due to the electrostatic attraction, the movable body 4A and the movable body 4B vibrate in opposite phases so as to repeatedly approach and separate in the X-axis direction. In the following, this vibration mode is also referred to as a "drive vibration mode". Then, when the angular velocity ωy is applied to the sensor element 4 while the movable body 4A and the movable body 4B are vibrating in the drive vibration mode, the movable detection electrodes 441A and 441B have opposite phases in the Z-axis direction due to the Coriolis force. The capacitance Ca and Cb change with this vibration. In the following, this vibration mode is also referred to as "detection vibration mode". Therefore, the angular velocity ωy can be obtained based on the changes in the capacitances Ca and Cb.

In the detection vibration mode, when the capacitance Ca becomes large, the capacitance Cb becomes small, and conversely, when the capacitance Ca becomes small, the capacitance Cb becomes large. Therefore, the detection signal obtained from the wiring 75, that is, the signal corresponding to the size of the capacitance Ca, and the detection signal obtained from the wiring 76, that is, the signal corresponding to the size of the capacitance Cb are differentially calculated, that is, subtracted. : By Ca-Cb, noise can be canceled and the angular velocity ωy can be detected more accurately.

The voltages V1 and V2 are not particularly limited as long as the drive vibration mode can be excited. Further, the inertial sensor 1 of the present embodiment is an electrostatic drive method that excites the drive vibration mode by electrostatic attraction, but the method for exciting the drive vibration mode is not particularly limited, and for example, a piezoelectric drive method. , An electromagnetic drive method using the Lorentz force of a magnetic field or the like can also be applied.

Further, the sensor element 4 has monitor units 49A and 49B for detecting the vibration state of the movable bodies 4A and 4B in the drive vibration mode. The monitor unit 49A has a comb-shaped movable monitor electrode 491A arranged on the movable detection electrode 441A, and fixed monitor electrodes 492A and 493A arranged in mesh with the comb-shaped movable monitor electrode 491A. Similarly, the monitor unit 49B comprises a comb-shaped movable monitor electrode 491B arranged on the movable detection electrode 441B and fixed monitor electrodes 492B and 493B arranged in mesh with the comb-shaped movable monitor electrode 491B. Have. Further, the fixed monitor electrodes 492A, 493A, 492B, and 493B are each drawn out to the outside of the recess 21 and bonded to the upper surface of the substrate 2 and fixed to the substrate 2.

The fixed monitor electrodes 492A and 492B are electrically connected to the wiring 77, and the fixed monitor electrodes 493A and 493B are electrically connected to the wiring 78. When the inertial sensor 1 is driven, a capacitance Cc is formed between the movable monitor electrode 491A and the fixed monitor electrode 492A and between the movable monitor electrode 491B and the fixed monitor electrode 492B, and the movable monitor electrode 491A and the fixed monitor are formed. Capacitance Cd is formed between the electrode 493A and between the movable monitor electrode 491B and the fixed monitor electrode 493B. When the movable bodies 4A and 4B vibrate in the X-axis direction in the drive vibration mode, the capacitances Cc and Cd change accordingly. Therefore, a detection signal is output based on the changes in the capacitances Cc and Cd, and the vibration state of the movable bodies 4A and 4B can be detected based on the output detection signal.

The vibration state of the movable bodies 4A and 4B detected by the outputs from the monitor units 49A and 49B is fed back to the drive circuit that applies the voltage V2 to the fixed drive electrodes 412A and 412B. The drive circuit changes the frequency, amplitude, duty ratio, etc. of the voltage V2 so that the amplitude of the movable bodies 4A and 4B becomes the target value. As a result, the movable bodies 4A and 4B can be vibrated in the target vibration state, and the detection accuracy of the angular velocity ωy is improved.

The sensor element 4 has been described above. As described above, the sensor element 4 can be formed by processing a silicon substrate by a Bosch process. However, when the Bosch process is used, for example, depending on the position in the chamber, the shape of the mask, etc., a through hole is dug in an oblique direction inclined with respect to the vertical direction. When the through hole is inclined, the cross-sectional shape of each part collapses from the rectangle, and in the present embodiment, the detection springs 46A and 46B are parallelograms as shown in FIG. There are various ways of collapsing from a rectangle, but in this embodiment, an example of a parallelogram is described as an example.

When the cross-sectional shape of each of the detection springs 46A and 46B collapses from the rectangle, the movable bodies 4A and 4B vibrate not only in the X-axis direction but also in the Z-axis direction in the drive vibration mode as shown by the arrows in FIG. Will end up. That is, a quadrature (unnecessary vibration) in the Z-axis direction is generated. Therefore, the movable bodies 4A and 4B vibrate in an oblique direction inclined with respect to the X-axis and the Z-axis. Therefore, the first state Q1 in which the movable bodies 4A and 4B vibrate in the direction indicated by the solid arrow from the natural state Q0 and the second state Q2 in which the movable bodies 4A and 4B vibrate in the direction indicated by the chain arrow from the natural state Q0 are alternately repeated. Is done. In the following, this vibration in the diagonal direction is also simply referred to as "diagonal vibration".

When such an oblique vibration occurs, the capacitances Ca and Cb change in the drive vibration mode, and a quadrature signal, which is a noise signal, is output accordingly. Therefore, the quadrature signal is mixed in the detection signal, and the detection accuracy of the angular velocity ωy is lowered. Therefore, in the present embodiment, the configurations of the detection units 44A and 44B are devised in order to reduce the quadrature signal caused by the above-mentioned quadrature.

Hereinafter, the configurations of the detection units 44A and 44B will be specifically described. However, since the detection units 44A and 44B have the same configurations, the detection unit 44A will be described as a representative and the detection unit 44B will be described below. , The explanation is omitted. As shown in FIG. 6, in a plan view from the Z-axis direction, the movable detection electrode 441A constituting the detection unit 44A has four sides forming a rectangle along the X-axis and the Y-axis. In particular, in the present embodiment, the movable detection electrode 441A has a substantially rectangular shape with the Y-axis direction as the long axis and the X-axis direction as the short axis.

As shown in FIG. 6, when the line that bisects the movable detection electrode 441A in the X-axis direction is the center line βx, the center of gravity G of the movable detection electrode 441A is shown in the direction along the X-axis from the center line βx. In the configuration, it is shifted to the minus side in the X-axis direction. Further, when the line that bisects the movable detection electrode 441A in the Y-axis direction is defined as the center line βy, the center of gravity G of the movable detection electrode 441A overlaps with the center line βy. That is, the center of gravity G is located side by side with the geometric center Oa of the movable detection electrode 441A when viewed from the Z-axis direction in the X-axis direction. However, the present invention is not limited to this, and for example, the center of gravity G may be deviated from the geometric center Oa in the X-axis direction and may be deviated in the Y-axis direction. When the movable detection electrode 441A is an ellipse other than a substantially rectangular shape, a polygon, or an indefinite shape, the center line βx has an area of the movable detection electrode 441A of 2 in a plan view from the Z-axis direction of the movable detection electrode 441A. It may be a line that divides evenly.

Further, as shown in FIG. 7, the separation distance D between the center of gravity G and the center line βx is smaller than the amplitude W of the movable detection electrode 441A in the X-axis direction. That is, D <W. By shifting the center of gravity G from the center line βx in the X-axis direction and setting D <W in this way, the quadrature can be suppressed and the quadrature signal can be reduced. The reason will be described below. Even within the range of D <W, for example, 0.2 ≦ D / W ≦ 0.8 is preferable, 0.3 ≦ D / W ≦ 0.7 is more preferable, and 0.4 ≦ 0.4. It is more preferable that ≦ D / W ≦ 0.6. As a result, the quadrature signal can be reduced more effectively.

First, the drive vibration mode will be described in more detail. As shown in FIG. 8, when the movable detection electrode 441A is driven in the drive vibration mode, a rotational moment around the Y axis indicated by arrows R1 and R2 is generated, and the movable detection electrode 441A vibrates with the rotational component shown in the figure. As described above, by shifting the center of gravity G from the center line βx and setting D <W, the inclination of the movable detection electrode 441A with respect to the X axis in the first state Q1 is compared with the conventional configuration in which the center of gravity G coincides with the center line βx. θ1 becomes large, and in the second state Q2, the inclination θ2 of the movable detection electrode 441A with respect to the X axis becomes small.

Therefore, as compared with the conventional configuration, the average separation distance D1 between the movable detection electrode 441A and the fixed detection electrode 71 is reduced in the first state Q1, and the movable detection electrode 441A and the fixed detection electrode 71 are reduced in the second state Q2. The average separation distance D2 between them increases. Therefore, the difference between the capacitance Ca in the first state Q1 and the capacitance Ca in the second state Q2 is smaller than that in the conventional configuration. That is, the amount of change in the capacitance Ca in the drive vibration mode is smaller than that in the conventional configuration, and as a result, the quadrature signal is reduced.

Next, one model will be described as to why the average separation distance D1 decreases and the average separation distance D2 increases as compared with the conventional configuration by adopting the configuration of the present embodiment. First, FIG. 9 shows a model having a conventional configuration. In this model, the distance between the fixed portions 42A, 451 (452) and the movable detection electrode 441A is L0, the mass of the movable detection electrode 441A is m, and the force to move the movable detection electrode 441A in the Z-axis direction by the quadracha is F0. be. In such a model, when the rotational moment applied to the negative end 441A'in the X-axis direction of the movable detection electrode 441A in the natural state Q0 is P', it is represented by P'= m, L0, F0 and is movable. When the rotational moment applied to the positive end 441A "in the X-axis direction of the detection electrode 441A is P", it is represented by P "= m · L0 · F0. In the conventional configuration, the center of gravity G is one with the center line βx. Because we are doing it, P'= P ".

Next, FIG. 10 shows a model of this embodiment. In this model, the distance between the fixed portions 451 and 452 located on the minus side in the X-axis direction and the movable detection electrode 441A is L1, and the distance between the fixed portions 42A located on the plus side in the X-axis direction and the movable detection electrode 441A. The distance is L2, the mass of the movable detection electrode 441A is m, and the force for moving the movable detection electrode 441A in the Z-axis direction by the quadrature is F0. Since the center of gravity G is deviated from the center line βx to the minus side in the X-axis direction, the relationship is L1 <L0 <L2.

In this model, when the rotational moment applied to the negative end 441A'in the X-axis direction of the movable detection electrode 441A in the first state Q1 is P1', it is represented by P1'= m, L1, F0, and the movable detection is performed. When the rotational moment applied to the positive end 441A "in the X-axis direction of the electrode 441A is P1", it is represented by P1 "= m · L0 · F0. And since L1 <L0 <L2, P1'. Therefore, as shown in FIG. 8, the inclination θ1 of the movable detection electrode 441A with respect to the X axis in the first state Q1 is larger than the inclination θ of the conventional configuration. That is, θ1> θ, which reduces the average separation distance D1 with respect to the conventional configuration.

On the contrary, when the rotational moment applied to the negative end 441A'in the X-axis direction of the movable detection electrode 441A in the second state Q2 is P2', it is represented by P2'=-m, L1, F0, and the movable detection is detected. When the rotational moment applied to the positive end 441A "in the X-axis direction of the electrode 441A is P2", it is represented by P2 "= −m ・ L2 ・ F0. Since L1 <L0 <L2, P2'> The relationship is P', P2 "<P". Therefore, as shown in FIG. 8, the inclination θ2 of the movable detection electrode 441A with respect to the X axis in the second state Q2 is smaller than the inclination θ of the prior art. That is, θ2 <θ. This increases the average separation distance D2 with respect to the conventional configuration.

From the above, it can be seen that the configuration of the present embodiment reduces the average separation distance D1 and increases the average separation distance D2 as compared with the conventional configuration.

In this embodiment, as shown in FIG. 8, in a plan view from the Z-axis direction, the region on the minus side in the X-axis direction, which is the center of gravity G side with respect to the center line βx of the movable detection electrode 441A, is the first. When the region M1 is set and the region on the plus side in the X-axis direction opposite to the center of gravity G is the second region M2, the average thickness t1 in the direction along the Z axis of the first region M1 is the second region M2. It is thicker than the average thickness t2 in the direction along the Z axis. That is, t1> t2. As a result, the center of gravity G can be more reliably shifted from the center line βx.

In particular, the lower surface 442A of the movable detection electrode 441A is composed of a stepped surface having at least one step. In the present embodiment, the lower surface 442A is composed of a stepped surface having one step 443A, a first surface 444A connected to the lower end of the step 443A, and a second surface 445A connected to the upper end of the step 443A. ing. By forming the lower surface 442A with a stepped surface in this way, t1> t2 can be achieved with a simple configuration. However, the stepped surface constituting the lower surface 442A is not particularly limited, and may have, for example, two or more steps.

The configuration of the inertial sensor 1 has been described above. Next, a method of manufacturing the inertial sensor 1 will be described. As shown in FIG. 11, the method for manufacturing the inertial sensor 1 includes a substrate preparation step for preparing the substrate 2, a step surface forming step for forming a step surface on the silicon substrate 40 which is the base material of the sensor element 4, and the substrate 2. It has a joining step of joining the silicon substrate 40, a sensor element forming step of patterning the silicon substrate 40 by a bosh process to form a sensor element 4, and a lid joining step of joining the lid 3 to the substrate 2.

[Board preparation process]
First, a glass substrate to be a base material of the substrate 2 is prepared. Next, the recess 21, the mounts 221, 222, 224 and the groove are formed in the glass substrate to obtain the substrate 2. The recesses 21, mounts 221, 222, 224 and grooves can be formed, for example, by wet etching. Next, the fixed detection electrodes 71, 72 and the wirings 73, 74, 75, 76, 77, 78 are formed on the substrate 2.

[Step forming process]
As shown in FIG. 12, a silicon substrate 40 as a base material of the sensor element 4 is prepared, and a stepped surface constituting the lower surfaces 442A and 442B of the movable detection electrodes 441A and 441B is formed on the lower surface of the silicon substrate 40. The stepped surface can be formed by, for example, various etchings such as dry etching and wet etching.

[Joining process]
As shown in FIG. 13, the silicon substrate 40 is bonded to the upper surface of the substrate 2. Next, if necessary, the silicon substrate 40 is thinned by using CMP (Chemical Mechanical Polishing).

[Sensor element forming process]
Next, as shown in FIG. 14, the silicon substrate 40 is patterned by the Bosch process to obtain the sensor element 4.

[Cover joining process]
Next, as shown in FIG. 15, a lid 3 is prepared and joined to the upper surface of the substrate 2 via a glass frit 39. As a result, the inertial sensor 1 is obtained.

The method of manufacturing the inertial sensor 1 has been described above. Further, as another manufacturing method of the sensor element 4, for example, as shown in FIG. 16, a sacrificial layer K whose upper surface is composed of a stepped surface is formed on the substrate 2, and then, as shown in FIG. 17, Polysilicon is formed on the sacrificial layer K to form the sensor element 4, and then, as shown in FIG. 18, the sacrificial layer K is removed and the sensor element 4 is released from the substrate 2. The sensor element 4 can also be formed by such a manufacturing method.

The inertial sensor 1 has been described above. As described above, such an inertial sensor 1 overlaps the substrate 2 in the direction along the substrate 2 and the Z axis and faces the substrate 2 when the three axes orthogonal to each other are the X axis, the Y axis, and the Z axis. It has a movable detection electrode 441A as a detection movable body, a fixed detection electrode 71 arranged on the substrate 2 and facing the movable detection electrode 441A, and a drive unit 41A for vibrating the movable detection electrode 441A. Further, the vibration of the movable detection electrode 441A has a drive vibration mode in which vibration in the direction along the X axis and vibration in the direction along the Z axis are combined. Further, when the center line βx is a line that bisects the movable detection electrode 441A in the direction along the X axis in a plan view from the Z-axis direction, the center of gravity G of the movable detection electrode 441A is from the center line βx to the X axis. The distance D between the center of gravity G and the center line βx is smaller than the amplitude W in the direction along the X axis of the movable detection electrode 441A. With such a configuration, the quadrature can be reduced, and the quadrature signal can be reduced accordingly.

Further, as described above, in a plan view from the Z-axis direction, the region on the center of gravity G side with respect to the center line βx of the movable detection electrode 441A is set as the first region M1, and the region on the side opposite to the center of gravity G is the second region. When the region M2 is set, the average thickness t1 in the direction along the Z axis of the first region M1 is thicker than the average thickness t2 in the direction along the Z axis of the second region M2. That is, t1> t2. As a result, the center of gravity G can be more reliably shifted from the center line βx.

Further, as described above, the lower surface 442A of the movable detection electrode 441A, that is, the surface facing the fixed detection electrode 71 has a step. From this, it is possible to set t1> t2 with a simple configuration.

<Second Embodiment>
FIG. 19 is a cross-sectional view showing the inertial sensor according to the second embodiment.

This embodiment is the same as the above-described first embodiment except that the configurations of the movable detection electrodes 441A and 441B, specifically, the method of shifting the center of gravity G from the center line βx are different. In the following description, the present embodiment will be mainly described with respect to the differences from the above-described embodiment, and the description thereof will be omitted for the same matters. Further, in FIG. 19, the same reference numerals are given to the same configurations as those of the above-described embodiment. Further, since the configurations of the movable detection electrodes 441A and 441B are the same, the movable detection electrode 441A will be described as a representative below, and the description of the movable detection electrode 441B will be omitted.

As shown in FIG. 19, the lower surface 442A of the movable detection electrode 441A is composed of an inclined surface that is inclined with respect to the X axis in a stationary state. Even with such a configuration, t1> t2 can be set with a simple configuration, and the center of gravity G can be shifted from the center line βx in the X-axis direction. In the present embodiment, the inclination angle of the lower surface 442A with respect to the X axis is the same over the entire area in the X-axis direction, but the present invention is not limited to this, and may have portions having different inclination angles. Further, in the present embodiment, the entire surface of the lower surface 442A is composed of an inclined surface, but the present invention is not limited to this, and for example, a part of the lower surface 442A is composed of an inclined surface and the rest is a surface parallel to the X axis. It may be configured.

As described above, in the present embodiment, the lower surface 442A of the movable detection electrode 441A, that is, the surface facing the fixed detection electrode 71 is inclined with respect to the X axis. From this, it is possible to set t1> t2 with a simple configuration.

The second embodiment as described above can also exert the same effect as the first embodiment described above.

<Third Embodiment>
FIG. 20 is a cross-sectional view showing an inertial sensor according to a third embodiment.

This embodiment is the same as the above-described first embodiment except that the configurations of the movable detection electrodes 441A and 441B, specifically, the method of shifting the center of gravity G from the center line βx are different. In the following description, the present embodiment will be mainly described with respect to the differences from the above-described embodiment, and the description thereof will be omitted for the same matters. Further, in FIG. 20, the same reference numerals are given to the same configurations as those of the above-described embodiment. Further, since the configurations of the movable detection electrodes 441A and 441B are the same, the movable detection electrode 441A will be described as a representative below, and the description of the movable detection electrode 441B will be omitted.

As shown in FIG. 20, the second region M2 of the movable detection electrode 441A has a recess 446A that opens to the lower surface 442A of the movable detection electrode 441A. Even with such a configuration, t1> t2 can be set with a simple configuration, and the center of gravity G can be shifted from the center line βx. In the present embodiment, one recess 446A is formed in the second region M2, but the number of recesses 446A is not limited to this, and may be two or more. Further, the recess 446A may be a through hole penetrating the upper surface of the movable detection electrode 441A. Further, when having two or more recesses 446A, all the recesses 446A may have the same shape, or at least one recess 446A may have a different width and depth from the other recesses 446A. Further, the first region M1 may also have a recess 446A.

As described above, in the present embodiment, the second region M2 has a recess 446A on the lower surface 442A of the movable detection electrode 441A, that is, the surface facing the fixed detection electrode 71. From this, it is possible to set t1> t2 with a simple configuration.

The third embodiment as described above can also exert the same effect as the first embodiment described above.

<Fourth Embodiment>
FIG. 21 is a plan view showing a smartphone as an electronic device according to the fourth embodiment.

The smartphone 1200 shown in FIG. 21 is the one to which the electronic device described in the embodiment is applied. The smartphone 1200 has a built-in inertial sensor 1 and a control circuit 1210 that controls based on a detection signal output from the inertial sensor 1. The detection data detected by the inertial sensor 1 is transmitted to the control circuit 1210, and the control circuit 1210 recognizes the posture and behavior of the smartphone 1200 from the received detection data and displays the display image displayed on the display unit 1208. You can change it, make a warning sound or sound, or drive a vibration motor to vibrate the main unit.

The smartphone 1200 as such an electronic device has an inertial sensor 1. Therefore, the effect of the inertial sensor 1 described above can be enjoyed, and high reliability can be exhibited.

In addition to the above-mentioned smartphone 1200, the electronic devices described in the embodiments include, for example, personal computers, digital still cameras, tablet terminals, watches, smart watches, inkjet printers, laptop personal computers, televisions, and HMDs. Wearable terminals such as head mount displays), video cameras, video tape recorders, car navigation devices, pagers, electronic notebooks, electronic dictionaries, calculators, electronic game equipment, word processors, workstations, videophones, security TV monitors, electronic binoculars, etc. It can be applied to POS terminals, medical equipment, fish finder, various measuring equipment, mobile terminal base station equipment, various instruments such as vehicles, aircraft and ships, flight simulators, network servers and the like.

<Fifth Embodiment>
FIG. 22 is an exploded perspective view showing an inertial measurement unit as an electronic device according to a fifth embodiment. FIG. 23 is a perspective view of the substrate included in the inertial measurement unit shown in FIG. 22.

The inertial measurement unit 2000 (IMU: Inertial Measurement Unit) as an electronic device shown in FIG. 22 is an inertial measurement unit that detects the posture and behavior of a mounted device such as an automobile or a robot. The inertial measurement unit 2000 functions as a 6-axis motion sensor including a 3-axis acceleration sensor and a 3-axis angular velocity sensor.

The inertial measurement unit 2000 is a rectangular cuboid having a substantially square plane shape. Further, screw holes 2110 as fixing portions are formed in the vicinity of two vertices located in the diagonal direction of the square. The inertial measurement unit 2000 can be fixed to the mounted surface of a mounted body such as an automobile by passing two screws through the two screw holes 2110. By selecting parts and changing the design, it is possible to reduce the size to a size that can be mounted on a smartphone or a digital camera, for example.

The inertial measurement unit 2000 has an outer case 2100, a joining member 2200, and a sensor module 2300, and has a configuration in which the sensor module 2300 is inserted by interposing the joining member 2200 inside the outer case 2100. There is. The outer shape of the outer case 2100 is a rectangular cuboid whose plane shape is substantially square, similar to the overall shape of the inertial measurement unit 2000 described above, and screw holes 2110 are formed in the vicinity of two vertices located in the diagonal direction of the square. Has been done. Further, the outer case 2100 has a box shape, and the sensor module 2300 is housed inside the outer case 2100.

The sensor module 2300 has an inner case 2310 and a substrate 2320. The inner case 2310 is a member that supports the substrate 2320, and has a shape that fits inside the outer case 2100. Further, the inner case 2310 is formed with a recess 2311 for preventing contact with the substrate 2320 and an opening 2312 for exposing the connector 2330 described later. Such an inner case 2310 is joined to the outer case 2100 via a joining member 2200. Further, the substrate 2320 is bonded to the lower surface of the inner case 2310 via an adhesive.

As shown in FIG. 23, on the upper surface of the substrate 2320, a connector 2330, an angular velocity sensor 2340z for detecting an angular velocity around the Z axis, an acceleration sensor 2350 for detecting acceleration in each axis of the X axis, the Y axis, and the Z axis, etc. Is implemented. Further, on the side surface of the substrate 2320, an angular velocity sensor 2340x for detecting the angular velocity around the X axis and an angular velocity sensor 2340y for detecting the angular velocity around the Y axis are mounted. Then, as each of these sensors, the inertial sensor of the present invention can be used.

Further, a control IC 2360 is mounted on the lower surface of the substrate 2320. The control IC 2360 is an MCU (Micro Controller Unit) and controls each part of the inertial measurement unit 2000. The storage unit stores a program that defines the order and contents for detecting acceleration and angular velocity, a program that digitizes the detection data and incorporates it into packet data, and accompanying data. In addition, a plurality of other electronic components are mounted on the substrate 2320.

<Sixth Embodiment>
FIG. 24 is a block diagram showing an overall system of a mobile positioning device as an electronic device according to a sixth embodiment. FIG. 25 is a diagram showing the operation of the mobile positioning device shown in FIG. 24.

The mobile body positioning device 3000 shown in FIG. 24 is a device that is attached to a moving body and used to perform positioning of the moving body. The moving body is not particularly limited, and may be any of a bicycle, an automobile, a motorcycle, a train, an airplane, a ship, and the like, but in the present embodiment, a case where a four-wheeled vehicle is used as the moving object will be described.

The mobile positioning device 3000 includes an inertial measurement unit 3100 (IMU), an arithmetic processing unit 3200, a GPS receiving unit 3300, a receiving antenna 3400, a position information acquisition unit 3500, a position synthesis unit 3600, and a processing unit 3700. , A communication unit 3800, and a display unit 3900. As the inertial measurement unit 3100, for example, the above-mentioned inertial measurement unit 2000 can be used.

The inertial measurement unit 3100 has a 3-axis accelerometer 3110 and a 3-axis angular velocity sensor 3120. The arithmetic processing unit 3200 receives the acceleration data from the acceleration sensor 3110 and the angular velocity data from the angular velocity sensor 3120, performs inertial navigation arithmetic processing on these data, and outputs inertial navigation positioning data including the acceleration and attitude of the moving body. do.

Further, the GPS receiving unit 3300 receives a signal from the GPS satellite via the receiving antenna 3400. Further, the position information acquisition unit 3500 outputs GPS positioning data representing the position (latitude, longitude, altitude), speed, and direction of the mobile positioning device 3000 based on the signal received by the GPS receiving unit 3300. The GPS positioning data also includes status data indicating a reception status, reception time, and the like.

The position synthesis unit 3600 is based on the inertial navigation positioning data output from the arithmetic processing unit 3200 and the GPS positioning data output from the position information acquisition unit 3500, and the position of the moving body, specifically, the position of the moving body on the ground. Calculate whether you are traveling at a position. For example, even if the position of the moving body included in the GPS positioning data is the same, as shown in FIG. 25, if the posture of the moving body is different due to the influence of the inclination θg of the ground or the like, the position of the moving body is different. It means that the moving body is running. Therefore, the accurate position of the moving body cannot be calculated only from the GPS positioning data. Therefore, the position synthesizing unit 3600 calculates which position on the ground the moving body is traveling by using the inertial navigation positioning data.

The position data output from the position synthesis unit 3600 is subjected to predetermined processing by the processing unit 3700 and displayed on the display unit 3900 as a positioning result. Further, the position data may be transmitted to an external device by the communication unit 3800.

<7th Embodiment>
FIG. 26 is a perspective view showing a moving body according to the seventh embodiment.

The automobile 1500 shown in FIG. 26 is an automobile to which the moving body according to the embodiment is applied. In this figure, vehicle 1500 includes at least one of the engine system, brake system and keyless entry system 1510. Further, the automobile 1500 has a built-in inertial sensor 1, and the inertial sensor 1 can detect the posture of the vehicle body. The detection signal of the inertial sensor 1 is supplied to the control device 1502, and the control device 1502 can control the system 1510 based on the signal.

As described above, the automobile 1500 as a moving body has the inertia sensor 1. Therefore, the effect of the inertial sensor 1 described above can be enjoyed, and high reliability can be exhibited.

In addition, the inertial sensor 1 includes a car navigation system, a car air conditioner, an anti-lock brake system (ABS), an airbag, a tire pressure monitoring system (TPMS), an engine control, and a hybrid vehicle. It can be widely applied to electronic control units (ECUs) such as battery monitors for electric vehicles and electric vehicles. Further, the moving body is not limited to the automobile 1500, and can be applied to, for example, an airplane, a rocket, an artificial satellite, a ship, an AGV (automated guided vehicle), a bipedal walking robot, an unmanned aerial vehicle such as a drone, and the like. ..

Although the inertial sensor, the electronic device, and the moving body of the present invention have been described above based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each part is an arbitrary configuration having the same function. Can be replaced with one. Further, any other constituent may be added to the present invention. Further, the above-described embodiments may be combined as appropriate. In the above-described embodiment, the configuration for detecting the angular velocity has been described as the inertial sensor, but the present invention is not limited to this, and for example, a configuration for detecting acceleration may be used.

1 ... inertial sensor, 21 ... recess, 2 ... substrate, 221, 222, 224 ... mount, 3 ... lid, 31 ... recess, 39 ... glass frit, 4 ... sensor element, 4A, 4B ... movable body, 40 ... silicon substrate , 40A, 40B ... Connection spring, 41A, 41B ... Drive unit, 411A, 411B ... Movable drive electrode, 412A, 412B ... Fixed drive electrode, 42A, 42B ... Fixed unit, 43A, 43B ... Drive spring, 44A, 44B ... Detection Section, 441A, 441B ... Movable detection electrode, 441A', 441A "... end, 442A, 442B ... bottom surface, 443A ... step, 444A ... first surface, 445A ... second surface, 446A ... recess, 451, 452 ... fixed portion , 46A, 46B ... Detection spring, 47A, 47B ... Beam, 48 ... Frame, 481, 482 ... Missing part, 488, 489 ... Frame spring, 49A, 49B ... Monitor part, 491A, 491B ... Movable monitor electrode, 492A, 492B , 493A, 493B ... Fixed monitor electrode, 71, 72 ... Fixed detection electrode, 73-78 ... Wiring, 1200 ... Smartphone, 1208 ... Display unit, 1210 ... Control circuit, 1500 ... Automobile, 1502 ... Control device, 1510 ... System, 2000 ... Inertivity measuring device, 2100 ... Outer case, 2110 ... Screw hole, 2200 ... Joining member, 2300 ... Sensor module, 2310 ... Inner case, 2311 ... Recess, 2312 ... Opening, 2320 ... Board, 2330 ... Connector, 2340x, 2340y , 2340z ... angular velocity sensor, 2350 ... acceleration sensor, 2360 ... control IC, 3000 ... mobile positioning device, 3100 ... inertial measurement device, 3110 ... acceleration sensor, 3120 ... angular velocity sensor, 3200 ... arithmetic processing unit, 3300 ... GPS receiver 3,400 ... Receiving antenna, 3500 ... Position information acquisition unit, 3600 ... Position synthesis unit, 3700 ... Processing unit, 3800 ... Communication unit, 3900 ... Display unit, D ... Separation distance, D1, D2 ... Average separation distance, G ... Center of gravity , K ... sacrificial layer, M1 ... first region, M2 ... second region, O ... center, Oa ... geometric center, P ... electrode pad, P', P ", P1', P2', P1", P2 "... Rotational moment, Q0 ... natural state, Q1 ... first state, Q2 ... second state, R1, R2 ... arrow, S ... storage space, V1, V2 ... voltage, W ... amplitude, α ... virtual straight line, βx, βy ... Center line, θ, θ1, θ2 ... tilt, θg ... tilt, ωy ... angular velocity

Claims (7)

When the three axes orthogonal to each other are the X-axis, Y-axis, and Z-axis,
With the board
A detection movable body that overlaps the substrate in the direction along the Z axis and faces the substrate.
A fixed detection electrode arranged on the substrate and facing the detection movable body, and
It has a drive unit that vibrates the detection movable body, and has
The vibration of the detected movable body has a drive vibration mode in which vibration in the direction along the X axis and vibration in the direction along the Z axis are combined.
In a plan view from the Z-axis direction
When the line that bisects the detected movable body in the direction along the X axis is used as the center line,
The center of gravity of the detected movable body is deviated from the center line in the direction along the X axis.
An inertial sensor characterized in that the distance between the center of gravity and the center line is smaller than the amplitude of the detection movable body in the direction along the X axis. In a plan view from the Z-axis direction
When the region on the center of gravity side with respect to the center line of the detection movable body is set as the first region and the region on the side opposite to the center of gravity is set as the second region.
The inertial sensor according to claim 1, wherein the average thickness of the first region along the Z axis is thicker than the average thickness of the second region along the Z axis. The inertial sensor according to claim 2, wherein the surface of the detection movable body facing the fixed detection electrode has a step. The inertial sensor according to claim 2, wherein the surface of the detection movable body facing the fixed detection electrode is inclined with respect to the X axis. The inertial sensor according to claim 2, wherein the second region has a recess on a surface of the detection movable body facing the fixed detection electrode. An electronic device comprising the inertial sensor according to any one of claims 1 to 5. A moving body having the inertial sensor according to any one of claims 1 to 5.

Images