WO2009090841A1

WO2009090841A1 - Electrostatic capacity type acceleration sensor

Info

Publication number: WO2009090841A1
Application number: PCT/JP2008/073435
Authority: WO
Inventors: Manabu Tamura
Original assignee: Alps Electric Co., Ltd.
Priority date: 2008-01-15
Filing date: 2008-12-24
Publication date: 2009-07-23

Abstract

Provided is an electrostatic capacity type acceleration sensor, which is made surface-mountable by using a conductive member extending through a substrate and which measures an acceleration highly sensitively. The acceleration sensor is constituted by joining one principal face of a silicon substrate (11) serving as a first substrate, which includes weight portions (12a, 12b and 12c) that are three movable electrodes for detecting the accelerations of an X-axis direction, a Y-axis direction and a Z-axis direction independently of one another, to a glass substrate (13) serving as a second substrate, which includes individually paired detecting electrode couples (14a, 14b, 14c, 14d, 14e and 14f) having predetermined spacings from the individual weight portions (12a, 12b and 12c). In the conductive members for the individual axes, as taken in a top plan view, a conducting member (16g) for a movable electrode is formed at an equidistant spacing from the individual conductive members (16e and 16f) for the detecting electrode couple of the Z-axis direction, and the conducting member (16g) for a movable electrode is formed at a relatively distant spacing from the conductive members (16a to 16d) of the X-axis direction and the Y-axis direction.

Description

Capacitance type acceleration sensor

The present invention relates to a capacitance type acceleration sensor that detects acceleration using capacitance.

As a sensor for detecting acceleration, for example, there is a capacitive acceleration sensor. This capacitance type acceleration sensor is composed of a fixed electrode and a movable electrode (weight) that swings when G (acceleration) is applied, and detects a change in capacitance between the fixed electrode and the movable electrode. By doing so, the acceleration can be obtained.

As such a capacitance type acceleration sensor, a silicon substrate is processed to form a plurality of weight portions which are movable electrodes, and a capacitance for calculating a change in physical quantity corresponding to the acceleration received by these weight portions. Type acceleration sensor (Patent Document 1).
JP 2002-181845 A

On the other hand, in order to make the capacitive acceleration sensor surface mountable, a lead electrode for the fixed electrode and the movable electrode is provided on one main surface of the substrate, and the lead electrode and the fixed electrode or the movable electrode are moved by a conductive member penetrating the substrate. A structure having an electrical connection with an electrode has been developed. In such a structure, the conductive member for the fixed electrode and the conductive member for the movable electrode are provided to penetrate through the substrate, and parasitic capacitance is generated between the conductive members, resulting in poor sensitivity. Is assumed.

The present invention has been made in view of the above points, and provides a capacitive acceleration sensor capable of measuring acceleration with high sensitivity in a structure that can be surface-mounted using a conductive member that penetrates a substrate. With the goal.

The capacitive acceleration sensor of the present invention is a capacitive acceleration sensor that detects at least acceleration in the Z-axis direction from a change in capacitance between a movable electrode functioning as a weight and a fixed electrode. A pair of detection electrode pairs for detecting at least one of the first substrate having electrodes and the movable electrode at a predetermined interval and detecting the capacitance as a capacitance difference is fixed electrode. A conductive member for the movable electrode and the fixed electrode that is electrically connected to the movable electrode and the fixed electrode and penetrates the inside, and is joined to one main surface of the first substrate. A substrate and a third substrate joined to the other main surface of the first substrate, wherein the movable electrode for the Z-axis direction is supported to be movable up and down by a bending beam with respect to the first substrate. In the plan view, the movable power Conductive members use is characterized in that it is arranged substantially equidistant away from each conductive member for detecting electrode pair for the Z-axis direction.

The capacitance-type acceleration sensor of the present invention independently detects accelerations in the X-axis direction, the Y-axis direction, and the Z-axis direction from changes in capacitance between the movable electrode functioning as a weight and the fixed electrode. A capacitance-type acceleration sensor, wherein a first substrate having three movable electrodes and at least one of the first substrate is opposed to each movable electrode at a predetermined interval, and the capacitance is defined as a capacitance difference. A pair of detection electrode pairs for detection as the fixed electrode, and a conductive member for the movable electrode and the fixed electrode that are electrically connected to the movable electrode and the fixed electrode and penetrate through the interior, A second substrate bonded to one main surface of the first substrate; and a third substrate bonded to the other main surface of the first substrate; and for the X-axis direction and the Y-axis direction. The movable electrode is a torsion beam with respect to the first substrate. The movable electrode for the Z-axis direction is supported so as to be movable up and down by a bending beam with respect to the first substrate, and in the plan view, the conductive member for the movable electrode is It is characterized by being disposed at a position approximately equidistant from each conductive member for the detection electrode pair for the Z-axis direction.

According to these configurations, the parasitic capacitance between the conductive member for the movable electrode and the conductive member for Z-axis detection, and the parasitic capacitance between the conductive member for the movable electrode and the conductive member for Z-axis reference, Are almost equal. Thereby, acceleration can be measured with high sensitivity.

In the capacitive acceleration sensor of the present invention, the conductive member for the movable electrode is disposed at a position relatively distant from the conductive member for the X-axis direction and the Y-axis direction in plan view. Is preferred.

According to the capacitance type acceleration sensor of the present invention, the capacitance type acceleration sensor detects at least the acceleration in the Z-axis direction from the change in capacitance between the movable electrode functioning as a weight and the fixed electrode. A first substrate having a movable electrode, and at least one of the movable substrate is opposed to the movable electrode at a predetermined interval, and a pair of detection electrode pairs for detecting the capacitance as a capacitance difference is provided. A second substrate having a plurality of conductive members electrically connected to the movable electrode and the fixed electrode and penetrating through the interior, and being joined to one main surface of the first substrate; A third substrate bonded to the other main surface of the first substrate, and the movable electrode for the Z-axis direction is supported by the bending beam with respect to the first substrate so as to be movable up and down. In, the conductive member for the movable electrode Since the Z-axis direction detection electrode pair is disposed at a position that is substantially equidistant from each detection electrode, in a structure that can be surface-mounted using a conductive member that penetrates the substrate, it is highly sensitive. Acceleration can be measured.

It is a top view which shows the electrostatic capacitance type acceleration sensor which concerns on embodiment of this invention. 2A is a cross-sectional view taken along line IIA-IIA in FIG. 1, and FIG. 2B is a cross-sectional view taken along line IIB-IIB in FIG. It is a figure which shows the relationship between the capacitance difference and acceleration in a capacitive acceleration sensor. (A)-(d) is a figure for demonstrating the manufacturing method of the capacitance-type acceleration sensor based on this invention. (A), (b) is a figure for demonstrating the manufacturing method of the electrostatic capacitance type acceleration sensor which concerns on this invention. (A)-(c) is a figure for demonstrating the manufacturing method of the capacitance-type acceleration sensor based on this invention. (A)-(c) is a figure which shows arrangement | positioning of the electrically-conductive member in the capacitive acceleration sensor which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a plan view showing a capacitive acceleration sensor according to an embodiment of the present invention. 2A is a cross-sectional view taken along line IIA-IIA in FIG. 1, and FIG. 2B is a cross-sectional view taken along line IIB-IIB in FIG.

The capacitive acceleration sensor shown in FIG. 1 includes first and

second weight portions

12a, 12b, and 12c that are three movable electrodes for independently detecting accelerations in the X-axis direction, the Y-axis direction, and the Z-axis direction. A pair of detection electrodes each having a predetermined distance from one main surface of the silicon substrate 11 as a single substrate and the

respective weight portions

12a, 12b, 12c and detecting a change in capacitance as a capacitance difference. The glass substrate 13 which is the second substrate having the

pairs

14a, 14b, 14c, 14d, 14e, and 14f is joined, and

weight portions

12a and 12b are formed on the other main surface of the silicon substrate 11. A glass substrate 15 that is a third substrate is bonded so as to constitute a region (cavity) 18 that is swung to raise and lower the weight portion 12c.

In the capacitive acceleration sensor shown in FIG. 1, the movable electrode sensitive to acceleration in the Y-axis direction is the weight portion 12a, the movable electrode sensitive to acceleration in the X-axis direction is the weight portion 12b, and Z The movable electrode sensitive to the acceleration in the axial direction is the weight portion 12c. The pair of detection electrode pairs for the Y-axis direction weight portion 12a are fixed

electrodes

14a and 14b, and the pair of detection electrode pairs for the X-axis direction weight portion 12b are fixed

electrodes

14c and 14d, which are for the Z-axis direction. A pair of detection electrodes for the weight portion 12c are fixed

electrodes

14e and 14f. Conductive members (penetrating electrodes) 16a and 16b are electrically connected to the

fixed electrodes

14a and 14b for the Y-axis direction weight portion 12a, respectively. The

fixed electrodes

14c and 14d for the X-axis direction weight portion 12b are connected to the

fixed electrodes

14a and 14b, respectively. The conductive members (penetrating electrodes) 16c and 16d are electrically connected to each other, and the conductive members (penetrating electrodes) 16e and 16f are electrically connected to the

fixed electrodes

14e and 14f with respect to the Z-axis direction weight portion 12c, respectively. It is connected.

The Y-axis direction weight portion 12a has a substantially rectangular shape in plan view, and is supported so as to be swingable with respect to the silicon substrate 11 by a torsion beam 11a on opposite sides. The X-axis direction weight portion 12b has a substantially rectangular shape in plan view, and is supported so as to be swingable with respect to the silicon substrate 11 by a torsion beam 11b on opposite sides. Each

torsion beam

11a, 11b is provided in the vicinity of the center of the opposite sides of the

weight portions

12a, 12b in plan view. On the other hand, the Z-axis direction weight portion 12c has a substantially rectangular shape in plan view, and the periphery thereof is supported by the bending beam 11c so as to be movable up and down with respect to the silicon substrate 11.

Three detection electrode pairs are formed on the glass substrate 13. The

fixed electrodes

14a and 14b with respect to the Y-axis direction weight part 12a have substantially the same area, and as can be seen from FIG. 1, in the plan view, below the Y-axis direction weight part 12a and torsion beams 11a. Is formed by dividing the central portion passing through the boundary (upper and lower divisions in FIG. 1). The total area of the two

fixed electrodes

14a and 14b is made substantially equal to the area of the weight portion 12a for the Y-axis direction.

The

fixed electrodes

14c and 14d with respect to the X-axis direction weight portion 12b have substantially the same area, and as can be seen from FIG. 1, in the plan view, below the X-axis direction weight portion 12b, Is formed by dividing the central portion passing through the boundary (left and right division in FIG. 1). The areas of the two fixed

electrodes

14c and 14d are combined to be approximately equal to the area of the weight portion 12b for the X-axis direction.

The fixed

electrodes

14e and 14f for the Z-axis direction weight portion 12c have substantially the same area as the Z-axis direction weight portion 12c, and one fixed electrode 14e is formed below the Z-axis direction weight portion 12c. The other fixed electrode 14f is formed in another region.

In this way, by adopting a configuration in which all three pairs of detection electrodes are formed on the same surface of the glass substrate 13, all the detection electrodes (fixed electrodes) can be formed in one process. This is preferable because the process can be simplified. Further, as shown in FIG. 1, the

weight parts

12a, 12b, 12c for the respective axial directions are arranged in parallel on the silicon substrate 11 and are formed so as to have substantially the same shape, thereby simplifying the manufacturing process. This is preferable.

Further, four electrodes, that is, a fixed

electrode pair

14c, 14d for the X-axis direction, a fixed

electrode pair

14a, 14b for the Y-axis direction, and two capacitance

difference detection electrodes

14e, 14f for the Z-axis direction, The glass substrates 13 are arranged in a substantially square shape in plan view. Thus, it is preferable that the fixed electrode is disposed because the region where the electrode is formed on the glass substrate 13 becomes uniform and the influence on the thermal stress becomes equal.

2A is a cross-sectional view taken along the line IIA-IIA in FIG. 1, and shows the configuration of the Y-axis direction weight portion 12a and the X-axis direction weight portion 12b. FIG. It is sectional drawing which follows the IIB-IIB line | wire, and shows the structure about the weight part 12c for Z-axis directions. 2A, fixed

electrodes

14a, 14b, 14c, and 14d are formed on one main surface of the glass substrate 13. In FIG. In FIG. 2A, the fixed

electrodes

14c and 14d for the X-axis direction weight portion 12b are shown, and the fixed

electrodes

14a and 14b for the Y-axis direction weight portion 12a are not shown.

The glass substrate 13 is provided with

conductive members

16c and 16d penetrating so as to be exposed at both main surfaces, and one of the exposed surfaces is electrically connected to the fixed

electrodes

14c and 14d, respectively.

Lead electrodes

17a and 17b are formed on the other exposed surfaces of the

conductive members

16c and 16d, and the

conductive members

16a and 16b and the

lead electrodes

17a and 17b are electrically connected to each other. Although not shown in FIG. 2A, the fixed

members

14a and 14b for the Y-axis direction weight portion 12a are also provided with conductive members and lead electrodes in the same configuration.

A silicon substrate 11 is bonded on the glass substrate 13. Here, an SOI (Silicon-On-Insulator) substrate is used as a silicon substrate in order to facilitate the formation of the beam portion. A glass substrate 15 is bonded on the silicon substrate 11. Accordingly, the cavity 18a in which the Y-axis direction weight portion 12a and the corresponding

fixed electrodes

14a and 14b are disposed, and the cavity in which the X-axis direction weight portion 12b and the corresponding fixed

electrodes

14c and 14d are disposed. 18b are formed. It should be noted that anodic bonding is used for bonding between the glass substrate 13 and the silicon substrate 11 or between the glass substrate 15 and the silicon substrate 11 in order to increase the airtightness of the

cavities

18a and 18b formed between the substrates. Preferably it is done. In the cavity 18a, the active layer 11f of the SOI substrate becomes a torsion beam 11a, and supports the Y-axis direction weight portion 12a so as to be swingable. In the cavity 18b, the active layer 11f of the SOI substrate is twisted 11b and supports the X-axis direction weight portion 12b so as to be swingable.

2B, fixed

electrodes

14e and 14f are formed on one main surface of the glass substrate 13. In FIG. The glass substrate 13 is provided with

conductive members

16e, 16f, and 16g penetrating so as to be exposed at both main surfaces, and one of the exposed surfaces is electrically connected to the fixed

electrodes

14e, 14f and the electrode 19, respectively. Has been. In addition,

lead electrodes

17c, 17d, and 17e are formed on the other exposed surfaces of the

conductive members

16e, 16f, and 16g, and the

conductive members

16e, 16f, and 16g and the

lead electrodes

17c, 17d, and 17e are electrically connected to each other. It is connected. The conductive member 16g is a common conductive member for the

weight portions

12a, 12b, and 12c that are movable electrodes.

A silicon substrate 11 is bonded on the glass substrate 13, and a glass substrate 15 is bonded on the silicon substrate 11. Thereby, a cavity 18c in which the Z-axis direction weight portion 12c and the corresponding fixed electrode 14e are arranged, and a cavity in which the Z-axis direction weight portion 12c fixed electrode 14f is arranged are formed. Accordingly, one of the detection electrodes for the Z-axis direction is sealed in an independent cavity different from the cavities of the movable electrodes in the X-axis, Y-axis, and Z-axis directions. It should be noted that anodic bonding is performed between the glass substrate 13 and the silicon substrate 11 or between the glass substrate 15 and the silicon substrate 11 in order to increase the airtightness of the cavity 18c formed between the substrates. Is preferred. Further, in the cavity 18a, the active layer 11f of the SOI substrate becomes a bending beam 11c, and supports the Z-axis direction weight portion 12c so as to be movable up and down.

The

torsion beams

11a and 11b and the bending beam 11c are formed on the bottom surfaces of the

weight portions

12a, 12b, and 12c. That is, each of the

weight portions

12a, 12b, and 12c has a pair of faces that face each other in the thickness direction of the silicon substrate 11, and the

torsion beams

11a and 11b and the bending beam 11c are respectively connected to the

weight portions

12a and 12b. , 12c is formed along one surface. As can be seen from FIG. 1, the

torsion beams

11a and 11b and the bending beam 11c pass through the positions of the centers of gravity of the

weight portions

12a, 12b and 12c, respectively. By forming such a beam, the sensitivity of the other axes can be lowered, and the acceleration in the direction of each axis can be detected independently.

In the present invention, as shown in FIG. 1, in a plan view, the conductive member 16g for the movable electrode is located at an approximately equal distance from the respective

conductive members

16e and 16f for the detection electrode pair for the Z-axis direction. Is arranged. The movable electrode conductive member 16g has a parasitic capacitance with each of the

conductive members

16e and 16f for the detection electrode pair for the Z-axis direction. Since the parasitic capacitance changes in size according to the distance, if the distance between the conductive member 16e and the conductive member 16g is substantially equal to the distance between the conductive member 16f and the conductive member 16g. The parasitic capacitance between the conductive member 16g and the conductive member 16e is substantially equal to the parasitic capacitance between the conductive member 16g and the conductive member 16f.

The acceleration in the Z-axis direction detects a change in capacitance due to a change in distance to the fixed electrode 14e due to the lifting and lowering of the weight portion 12c as a capacitance difference from the reference electrode 14f. If there is a difference between the parasitic capacitance between the conductive member 16g and the conductive member 16e and the parasitic capacitance between the conductive member 16g and the conductive member 16f, as shown by the characteristic line A shown in FIG. The absolute value of increases. In this case, the sensitivity S ′ of the capacitive acceleration sensor is (C ₁ ′ −C ₀ ′) / C ₀ ′. On the other hand, if the parasitic capacitance between the conductive member 16g and the conductive member 16e is substantially equal to the parasitic capacitance between the conductive member 16g and the conductive member 16f, the differential capacitance is as shown by the characteristic line B in FIG. The absolute value is small. In this case, the sensitivity S of the capacitive acceleration sensor is (C ₁ -C ₀ ) / C ₀ . Thus, the sensitivity S is larger than the sensitivity S ′ when there is a difference between the two parasitic capacitances because the absolute value of the difference capacitance is small because there is no difference between the two parasitic capacitances. Therefore, in plan view, the conductive member 16g for the movable electrode is disposed at a position approximately equidistant from the respective

conductive members

16e and 16f for the detection electrode pair for the Z-axis direction, so that the substrate is In a structure that can be surface-mounted using a penetrating conductive member, acceleration can be measured with high sensitivity.

In the present invention, as shown in FIG. 1, the conductive member 16g for the movable electrode is disposed at a position relatively distant from the conductive members 16a to 16d for the X-axis direction and the Y-axis direction in plan view. It is preferable that As described above, since the parasitic capacitance between the conductive members changes depending on the distance, the conductive member 16g for the movable electrode is relative to the conductive members 16a to 16d for the X-axis direction and the Y-axis direction. Therefore, the absolute value error of the differential capacitance due to the parasitic capacitance in the X-axis direction and Y-axis direction acceleration detection units can be reduced. Thereby, acceleration can be measured with higher sensitivity.

In the capacitive acceleration sensor having such a configuration, when acceleration in the X-axis direction is applied, the X-axis direction weight portion 12b swings about the torsion beam 11b as a fulcrum. As the weight 12b swings and displaces in this way, the distance between the opposed fixed

electrodes

14c and 14d changes, and a change in capacitance due to the change in the distance can be detected as a capacitance difference. The acceleration can be measured by the capacitance change. Further, when acceleration in the Y-axis direction is applied, the Y-axis direction weight portion 12a swings with the torsion beam 11a as a fulcrum. As the weight 12a swings and displaces in this way, the distance between the opposed fixed

electrodes

14a and 14b changes, and a change in capacitance due to the change in the distance can be detected as a capacitance difference. The acceleration can be measured by the capacitance change. Further, when acceleration in the Z-axis direction is applied, the Z-axis direction weight portion 12c moves up and down by the bending beam 11c. As the weight portion 12c moves up and down in this way, the distance between the opposed fixed electrodes 14e changes, and a change in capacitance due to the change in the distance is detected as a difference in capacitance from the reference electrode 14f. The acceleration can be measured by the change in capacitance.

Next, an example of a manufacturing method of the capacitive acceleration sensor having the above configuration will be described.
4 (a) to (d), FIGS. 5 (a) and 5 (b), and FIGS. 6 (a) to 6 (c) are diagrams for explaining a method of manufacturing a capacitive acceleration sensor according to the present invention. It is.

As shown in FIG. 4 (a), protrusions to be

conductive members

16e, 16f, and 16g are formed on one main surface of the silicon substrate 16 by photolithography and dry etching. Next, the glass substrate 13 is placed on the protruding portion of the silicon substrate 16 and, as shown in FIG. 4B, both substrates are bonded so that the protruding portion is embedded in the glass substrate 13 by pressing while heating. Then, as shown in FIG.4 (c), both the main surfaces of the obtained composite_body | complex are grind | polished and the

electroconductive members

16e, 16f, and 16g are exposed by both main surfaces. 4 shows the configuration corresponding to FIG. 2B, the configuration corresponding to FIG. 2A is also formed at the same time. That is, conductive members for the fixed

electrodes

14a, 14b, 14c, and 14d corresponding to the X-axis direction weight portion 12b and the Y-axis direction weight portion 12a are formed in the same manner.

Next, as shown in FIG. 4D, an electrode material is deposited on the exposed

conductive members

16e, 16f, and 16g by sputtering, and fixed

electrodes

14e and 14f and an electrode 19 are formed by photolithography and etching, respectively. . The conductive member for each axis is formed so that the conductive member 16g for the movable electrode is separated from the respective

conductive members

16e and 16f for the detection electrode pair for the Z-axis direction by substantially equal distances in plan view. The movable electrode conductive member 16g is formed at a position relatively far from the X-axis direction and Y-axis direction conductive members 16a to 16d.

Next, as shown in FIG. 5A, the active layer 11f and the base layer 11e of the SOI substrate (silicon substrate 11) having the active layer 11f, the insulating layer 11d, and the base layer 11e are respectively formed into the recesses 11h by photolithography and etching. , 11g. The thickness of the active layer 11f of the SOI substrate corresponds to the thickness of the beam. Next, as shown in FIG. 5B, the bending beam 11c is formed by photolithography and etching the active layer 11f. 5 shows the configuration corresponding to FIG. 2B, the configuration corresponding to FIG. 2A is also formed at the same time. That is, the

torsion beams

11a and 11b and the recess 11g corresponding to the X-axis direction weight portion 12b and the Y-axis direction weight portion 12a are formed in the same manner.

Next, as shown in FIG. 6A, the silicon substrate shown in FIG. 5B is formed so that the active layer 11f of the SOI substrate covers the fixed electrode of the glass substrate 13 having the structure shown in FIG. 4D. 11 are laminated, and both

substrates

11 and 13 are bonded. At this time, it is preferable to perform bonding by anodic bonding. Next, as shown in FIG. 6B, the base layer of the SOI substrate and predetermined portions of the insulating layer 11d are removed by photolithography and etching to form the Z-axis direction weight portion 12c. Next, as shown in FIG. 6C, a glass substrate 15 is bonded onto the base layer 11e of the SOI substrate. At this time, it is preferable to perform bonding by anodic bonding. Next, electrode materials are deposited on the

conductive members

16e, 16f, and 16g exposed on the main surface of the glass substrate 13, and lead

electrodes

17c, 17d, and 17e are formed by photolithography and etching, respectively.

The capacitive acceleration sensor thus obtained can independently detect accelerations in the X-axis direction, the Y-axis direction, and the Z-axis direction. In this configuration, with respect to the conductive member for each axis, the conductive member 16g for the movable electrode is separated from each of the

conductive members

16e and 16f for the detection electrode pair for the Z-axis direction by a substantially equal distance in plan view. The movable electrode conductive member 16g is formed at a position relatively distant from the X-axis direction and Y-axis direction conductive members 16a to 16d, so that the conductive member 16g is formed between the conductive member 16g and the conductive member 16e. And the parasitic capacitance between the conductive member 16g and the conductive member 16f are substantially equal. Thereby, acceleration can be measured with high sensitivity.

Next, examples carried out to clarify the effects of the present invention will be described.
The parasitic capacitance between the conductive members in the plan view arrangement shown in FIGS. 7A to 7C was calculated. The results are shown in Table 1 below. In addition, the parasitic capacitance calculated the capacity | capacitance at the time of 1V application using electric field simulation.

In the configuration (Example 1) shown in FIG. 7A, the movable electrode conductive member 24 is disposed between the X-axis direction sensor 21 and the Y-axis direction sensor 22 and is used for Z-axis detection. The conductive member 23a and the Z-axis reference conductive member 23b are arranged at an approximately equal distance. 7B, the movable electrode conductive member 24 is disposed between the Z-axis detecting conductive member 23a and the Z-axis reference conductive member 23b. The Z-axis detection conductive member 23a and the Z-axis reference conductive member 23b are arranged at substantially the same distance. In the configuration shown in FIG. 7B, the movable electrode conductive member 24 is positioned relatively far from the X-axis direction sensor 21 (conductive member) and the Y-axis direction sensor 22 (conductive member). Has been placed. Further, as a reference example, the configuration shown in FIG. 7C, that is, the movable electrode conductive member 24 is disposed at the end of the substrate, and the Z-axis detection conductive member 23a and the Z-axis reference conductive member 23b are provided. Parasitic capacitance was also calculated for the components arranged at different distances.

Table 1 shows the parasitic capacitance between the conductive member 24 for the movable electrode and the conductive member of each axis. Since this capacitance type acceleration sensor detects the acceleration using the capacitance difference between p and n, the capacitance difference between the conductive members that do not contribute to the detection unit is preferably as small as possible. As can be seen from Table 1, in the case of the reference example, the difference is about 41 fF at maximum, but it is reduced to 13 fF in Example 1 and to 32.8 fF in Example 2. Thus, the capacitive acceleration sensor according to the present invention can detect acceleration with high sensitivity.

The present invention is not limited to the above embodiment, and can be implemented with various modifications. Although the case where a glass substrate and a silicon substrate are used has been described in the above embodiment, a substrate other than a glass substrate or a silicon substrate may be used in the present invention. Further, the thickness and material of the electrode and each layer in the sensor can be set as appropriate without departing from the effects of the present invention. Further, the process described in the above embodiment is not limited to this, and the process may be performed by changing the order as appropriate. For example, although the gap is formed on the side of the SOI substrate 11 that is the opposite surface, the gap may be formed by etching the glass substrate 13. Other modifications may be made as appropriate without departing from the scope of the object of the present invention.

Claims

A capacitance type acceleration sensor for detecting at least acceleration in the Z-axis direction from a change in capacitance between a movable electrode functioning as a weight and a fixed electrode, the first substrate having the movable electrode, and the movable electrode In contrast, at least one of them is opposed to each other with a predetermined interval, and has a pair of detection electrode pairs for detecting the capacitance as a capacitance difference as the fixed electrode, and the movable electrode and the fixed electrode A second substrate that has a conductive member for a movable electrode and a fixed electrode that are electrically connected and penetrates the inside, and is joined to one main surface of the first substrate; and the other main member of the first substrate A third substrate bonded to the surface, and the movable electrode for the Z-axis direction is supported so as to be movable up and down by a bending beam with respect to the first substrate. The conductive member is for the Z-axis direction. Capacitive acceleration sensor, characterized in that it is arranged substantially equidistant away from each conductive member for electrode pair out.
A capacitance-type acceleration sensor that independently detects accelerations in the X-axis direction, the Y-axis direction, and the Z-axis direction from a change in capacitance between a movable electrode that functions as a weight and a fixed electrode. A pair of detection electrode pairs for detecting the electrostatic capacitance as a capacitance difference, wherein at least one of the first substrate having one movable electrode is opposed to each movable electrode at a predetermined interval. As the fixed electrode, and has a conductive member for the movable electrode and the fixed electrode that are electrically connected to the movable electrode and the fixed electrode and penetrates the inside thereof, and is bonded to one main surface of the first substrate. And a third substrate bonded to the other main surface of the first substrate, and the X-axis direction and Y-axis direction movable electrodes are twisted with respect to the first substrate. Z is supported by a beam so that it can swing. A movable electrode for a direction is supported by a bending beam with respect to the first substrate so that the movable electrode can be moved up and down, and the conductive member for the movable electrode is respectively provided for the detection electrode pair for the Z-axis direction in a plan view. A capacitive acceleration sensor, which is disposed at a position substantially equidistant from the conductive member.
3. The electrostatic capacitance according to claim 2, wherein the conductive member for the movable electrode is disposed at a position relatively distant from the conductive member for the X-axis direction and the Y-axis direction in a plan view. Type acceleration sensor.