JP2020034290A - Sensor, structure, and electric device - Google Patents

Abstract

To provide a sensor capable of suppressing a decrease in performance.SOLUTION: A sensor includes a first fixed electrode 21 provided on a substrate, a second fixed electrode 22 provided on the substrate, and a movable electrode 26 arranged above the first fixed electrode and the second fixed electrode and including an opening 25. A MEMS device includes a first torsion spring 31 whose one end is connected to an inner wall of the opening, and a first beam part 41 connected to the other end of the first torsion spring and including a bent part when viewed from above the opening 25. The MEMS device further includes a second torsion spring 32 whose one end is connected to the inner wall of the opening, and a second beam part 42 connected to the other end of the second torsion spring and including a bent part when viewed from above the opening 25.SELECTED DRAWING: Figure 1

Description

  Embodiments of the present invention relate to sensors, structures, and electrical equipment.

  2. Description of the Related Art An acceleration sensor (hereinafter, referred to as a MEMS acceleration sensor) formed using MEMS (Micro Electro Mechanical Systems) technology to detect acceleration is known. This MEMS acceleration sensor is formed using a semiconductor process. Therefore, the performance of the MEMS acceleration sensor is affected by the semiconductor process.

U.S. Pat. No. 8,881,161

  An object of the present invention is to provide a sensor, a structure, and an electric device that can suppress a decrease in performance.

  A sensor according to an embodiment includes a substrate, a first fixed electrode provided on the substrate, a second fixed electrode provided on the substrate, the first fixed electrode, and the second fixed electrode. And a movable electrode having an opening. The sensor further includes a first torsion spring having one end connected to the inner wall of the opening, and a first torsion spring connected to the other end of the first torsion spring and having a bent portion as viewed from above the opening. And a beam portion. The sensor further includes a second torsion spring having one end connected to the inner wall of the opening, a second torsion spring connected to the other end of the second torsion spring, and having a bent portion as viewed from above the opening. And a beam portion.

The structure of the embodiment includes a substrate of the sensor, a first fixed electrode, a second fixed electrode, a movable electrode, a first torsion spring, a first beam, a second torsion spring, and a second beam. Including.
The electric device of the embodiment includes the above-described sensor.

FIG. 1 is a plan view schematically showing a MEMS acceleration sensor according to one embodiment. FIG. 2 is a sectional view taken along line 2-2 of FIG. FIG. 3 is a sectional view taken along line 3-3 in FIG. FIG. 4 is a sectional view taken along line 4-4 in FIG. FIG. 5 is a sectional view taken along line 5-5 in FIG. FIG. 6 is a sectional view corresponding to FIG. 2 when a force acts on the MEMS acceleration sensor of FIG. FIG. 7 is a plan view and a sectional view schematically showing a MEMS acceleration sensor of a comparative example. FIG. 8 is a diagram for explaining the reason why a decrease in detection sensitivity can be suppressed in the MEMS acceleration sensor according to the embodiment. FIG. 9 is a cross-sectional view corresponding to FIG. 3 of the MEMS acceleration sensor in which the movable electrode is warped. FIG. 10 is a cross-sectional view corresponding to FIG. 4 of the MEMS acceleration sensor in which the movable electrode is warped. FIG. 11 is a cross-sectional view corresponding to FIG. 5 of the MEMS acceleration sensor in which the movable electrode is warped. FIG. 12 is a plan view for explaining the dimensions of the MEMS acceleration sensor according to the embodiment. FIG. 13 is a cross-sectional view for explaining the method for manufacturing the MEMS acceleration sensor according to the embodiment. FIG. 14 is a plan view schematically showing a MEMS acceleration sensor according to another embodiment. FIG. 15 is a block diagram showing a MEMS acceleration sensor according to still another embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and dimensions and ratios of the drawings are not necessarily the same as actual ones. In the drawings, the same reference numerals are given to the same or corresponding parts, and duplicate description will be made as necessary. For the sake of simplicity, the same or corresponding parts may not be denoted by reference numerals.

  FIG. 1 is a plan view schematically showing a MEMS acceleration sensor according to one embodiment. FIG. 2 is a sectional view taken along line 2-2 of FIG. FIG. 3 is a sectional view taken along line 3-3 in FIG. FIG. 4 is a sectional view taken along line 4-4 in FIG. FIG. 5 is a sectional view taken along line 5-5 in FIG. The cross-sectional views of FIGS. 2 to 5 show a state when no force is acting on the MEMS acceleration sensor.

2 to 5, reference numeral 10 denotes a substrate. The substrate 10 includes a silicon substrate 11 and a silicon oxide film 12 provided thereon. 2 to 5 show only the upper part of the silicon substrate 11 for simplification.
As shown in FIG. 2, a first fixed electrode 21 is provided on the upper surface 10a (first surface) of the substrate 10. Here, the upper surface 10a of the substrate 10 is the upper surface of the silicon oxide film 12.

  In FIG. 1, the X axis (first axis) is an axis in the upper surface 10a of the substrate 10 in FIG. 2, and the Y axis (second axis) is an axis in the upper surface 10a of the substrate 10; The axis is perpendicular to. The Z axis (third axis) is an axis perpendicular to the X axis and the Y axis. As shown in FIG. 1, the first fixed electrode 21 extends along the X axis.

  On the upper surface 10a of the substrate 10, a second fixed electrode 22 is further provided. The second fixed electrode 22 extends along the X-axis and is arranged apart from the first fixed electrode 21 along the Y-axis. The area of the second fixed electrode 22 is the same as the area of the first fixed electrode 11. The distance from the torsion spring 31 to the second fixed electrode 22 is the same as the distance from the torsion spring 31 to the first fixed electrode 21. The wiring layer 23 is provided on the upper surface 10a of the substrate 10. On the silicon oxide film 12, the first fixed electrode 21, the second fixed electrode 22, and the wiring layer 23, a silicon nitride film (etching stopper) 24 is provided.

  As shown in FIGS. 1 and 2, a movable electrode 26 having an opening 25 is disposed above the first fixed electrode 21 and the second fixed electrode 22. When the MEMS acceleration sensor of the present embodiment is manufactured by using a sacrificial film process, the movable electrode 26 has a plurality of through holes (not shown).

  One end of a first torsion spring 31 is connected to the inner wall of the opening 25. The first torsion spring 31 extends along the X axis. As shown in FIG. 1, the other end of the first torsion spring 31 is connected to a first beam portion 41 having a bent portion when viewed from above the opening 25. The bent portion of the first beam portion 41 is connected to a rectangular parallelepiped portion 41a parallel to the X axis and this portion 41a, and is connected to a rectangular parallelepiped portion 41b parallel to the Y axis and this portion 41b. And a rectangular parallelepiped portion 41c parallel to the axis. The other end of the first torsion spring 31 is connected to the center of the portion 41b of the first beam portion 41. The first torsion spring 31 is connected to the movable electrode 26.

  As shown in FIG. 1, an anchor part 51 and an anchor part 52 are arranged on a substrate (not shown) so as to sandwich the first torsion spring 31. The anchor part 51 and the anchor part 52 are arranged at a certain distance from the first torsion spring 31. The anchor portion 51 is connected to the portion 41a, and the anchor portion 52 is connected to the portion 41c.

  As shown in FIG. 2, the anchor portions 51 and 52 penetrate through the silicon nitride film 24 and are electrically connected to the wiring layer 23. As shown in FIG. 4, the anchor portion 51 includes an insulating film 61 and a plug 62. The material of the plug 62 is, for example, tungsten. The plug 62 penetrates through the insulating film 61 and the insulating layer 24 and is electrically connected to the wiring layer 23. In the present embodiment, the number of plugs 62 is four, but the number is not limited to four. The configuration of the anchor portion 52 is the same as the configuration of the anchor portion 51. The first beam portion 41, the anchor portion 51, and the anchor portion 52 have a line-symmetric pattern with respect to the first torsion spring 31.

  One end of a second torsion spring 32 is connected to the inner wall of the opening 25. The second torsion spring 32 extends along the X axis. A portion of the inner wall of the opening 25 to which one end of the first torsion spring 31 is connected (first connection portion) is a portion of the inner wall of the opening 25 to which one end of the second torsion spring 32 is connected (second connection). Connection portion). More specifically, the first connection portion and the second connection portion face each other along the X axis.

  As shown in FIG. 1, the other end of the second torsion spring 32 is connected to a second beam portion 42 having a bent portion when viewed from above the opening 25. The bent portion of the second beam portion 42 is connected to a rectangular parallelepiped portion 42a parallel to the X axis and this portion 42a, and is connected to a rectangular parallelepiped portion 42b parallel to the Y axis and this portion 42b. And a rectangular parallelepiped portion 42c parallel to the axis. The other end of the second torsion spring 32 is connected to the center of the portion 42b. There is a gap between the portion 42b and the portion 41b. The second torsion spring 32 is connected to the movable electrode 26 similarly to the first torsion spring 31.

  As shown in FIG. 1, an anchor 53 and an anchor 54 are arranged on a substrate (not shown) so as to sandwich the second torsion spring 32. The anchor part 53 and the anchor part 54 are arranged at a certain distance from the second torsion spring 32. The anchor portion 53 is connected to the portion 42a, and the anchor portion 54 is connected to the portion 42c.

The anchor portion 51 and the anchor portion 54 indirectly contact the substrate 10. The anchor 53 and the anchor 54 have the same configuration as the anchor 51 and the anchor 52, respectively.
As shown in FIG. 1, when viewed from above the opening 25, the torsion spring 31, the first beam 41, the anchor 51, the torsion spring 32, the first beam 41, and the anchor 51 are inside the opening. Are located. As shown in FIG. 1, when viewed from above the opening 25, the first pattern formed by the first beam portion 41, the anchor portion 51, and the anchor portion 52 is different from the line 50 by the second beam portion. The second pattern formed by the portion 42, the anchor portion 53, and the anchor portion 54 is line-symmetric. The line 50 is a line that passes through the center between the portion 41b of the first beam portion 41 and the portion 42b of the second beam portion 42 and is parallel to the Y axis. The first pattern is not directly connected to the second pattern. The first pattern is connected via a first torsion spring 31, a movable electrode 26, and a second torsion spring 32.

In the present embodiment, it is assumed that the movable electrode 26, the first torsion spring 31, the second torsion spring 32, the first beam 41, and the second beam 42 are formed using the same material film. However, the films need not necessarily be made of the same material.
As shown in FIG. 2, the first fixed electrode 21 and the movable electrode 26 constitute a first capacitor C1, and the second fixed electrode 22 and the movable electrode 26 constitute a second capacitor C2. . In FIG. 2, the distance between the first fixed electrode 21 and the movable electrode 26 is the same as the distance between the second fixed electrode 22 and the movable electrode 26, and the capacitance of the first capacitor C1 is equal to the second capacitance. It is the same as the capacitance of the capacitor C1. Hereinafter, the capacitance is simply referred to as a capacitance.

FIG. 6 is a cross-sectional view corresponding to FIG. 2 when a force acts on the MEMS acceleration sensor of the present embodiment. The force includes a force perpendicular to the upper surface 10a of the substrate 10.
When the above-described vertical force acts on the MEMS acceleration sensor, the torsion spring 31 and the torsion spring 32 are twisted, and the distance between the first fixed electrode 21 and the movable electrode 26 is equal to the distance between the second fixed electrode 22 and the movable electrode 26. Is no longer the same as As a result, the capacitance between the first fixed electrode 21 and the movable electrode 26 is different from the second capacitance between the second fixed electrode 22 and the movable electrode 26. The difference between these capacities (capacity difference) changes according to the magnitude of the vertical force. Therefore, acceleration in the Z-axis direction (height direction) can be calculated based on the capacitance difference. The detection of the capacitance difference and the calculation of the acceleration are performed using, for example, a circuit (not shown) formed in the silicon substrate 11. The circuit is configured using, for example, a CMOS circuit. The CMOS circuit is formed using a silicon substrate 11 and a silicon oxide film 12.

The movable electrode 26 is formed using, for example, a silicon germanium film, a silicon film, a stacked film of a silicon film and a silicon oxide film, or a stacked film of a silicon oxide film, a silicon film, and a silicon oxide film. When these films are formed using a CVD (Chemical Vapor Deposition) process, the above-described films are warped. One cause of the warpage is that residual stress is generated in a film formed using a CVD process. Another cause is that thermal expansion occurs in the film due to a temperature change during or after the CVD process. As a result, as shown in FIG. In the case of a MEMS acceleration sensor of a type in which the movable electrode 26 is supported by the anchor portion 51 (comparative example), the movable electrode 26 is warped as shown in FIG. 7B. In FIG. 7B, the warped movable electrode 26 is schematically shown by a solid line. The movable electrode without warpage is schematically shown by a broken line. As shown in FIG. 7B, the movable electrode 26 is warped such that a peripheral portion of the movable electrode 26 is located above a central portion of the movable electrode 26.

  In the case of FIG. 7, the interval between the warped movable electrode 26 and the fixed electrode (not shown) is larger than the interval between the unwarped movable electrode and the fixed electrode (not shown). Therefore, the MEMS acceleration sensor using the warped movable electrode 26 has lower acceleration detection sensitivity than the MEMS acceleration sensor using the warped movable electrode. Here, the acceleration detection sensitivity is defined by a change in capacitance per unit acceleration. In the case of the present embodiment, since the MEMS acceleration sensor is a differential acceleration sensor that detects acceleration based on the above-described capacitance difference, the acceleration detection sensitivity is defined by a capacitance difference (= capacity C2−capacity C1).

However, when the MEMS acceleration sensor of the present embodiment was evaluated, it was confirmed that a decrease in the acceleration detection sensitivity could be suppressed. The reason is considered as follows.
FIG. 8A is a plan view corresponding to FIG. FIG. 8B is a sectional view taken along line 8b-8b in FIG. In FIG. 8B, the warped movable electrode 26 is schematically illustrated by a solid line, and the unwarped movable electrode is schematically illustrated by a broken line.

  As shown in FIGS. 8A and 8B, with respect to the X axis, in the region 71 outside the anchor portion 51 (52), the warped movable electrode 26 is above the non-warped movable electrode. Similarly, with respect to the X axis, in the region 72 outside the anchor portion 53 (54), the warped movable electrode 26 is above the non-warped movable electrode. Therefore, the detection sensitivity is reduced in the regions 71 and 72.

On the other hand, with respect to the X axis, in a region 73 inside the anchor portion 51 (52) and inside the anchor portion 53 (54), the warped movable electrode 26 is located below the non-warped movable electrode. is there. Therefore, in the region 73, the detection sensitivity is improved.
In the case of the present embodiment, the degree of improvement in the acceleration detection sensitivity in the area 73 is almost the same as the degree of the decrease in the acceleration detection sensitivity in the areas 71 and 72, so that the reduction in the acceleration detection sensitivity is suppressed. It is considered possible.

When the amount of warpage of the movable electrode 26 is defined by a radius of curvature, for example, if the radius of curvature is in the range of 20 mm to 200 mm, a decrease in the sensitivity of acceleration detection can be suppressed.
In FIG. 8B, G1 is a distance measured along the Z axis, and the maximum value of the distance (gap) from the warped movable electrode 26 to the warped movable electrode 26 in the region 73. Is shown.

  FIG. 9 is a sectional view corresponding to FIG. 3 of the MEMS acceleration sensor in which the movable electrode 26 is warped, and FIG. 10 is a sectional view corresponding to FIG. 4 of the MEMS acceleration sensor in which the movable electrode 26 is warped. FIG. 11 is a sectional view corresponding to FIG. 5 of the MEMS acceleration sensor in which the movable electrode 26 is warped. 9 to 11, broken lines indicate movable electrodes without warpage.

  FIG. 12 is a plan view for explaining dimensions of the MEMS acceleration sensor. In FIG. 12, X1 and X2 indicate dimensions of a portion parallel to the X axis, and Y1 to Y4 indicate dimensions of a portion parallel to the Y axis. To avoid complication of the drawings, reference numerals for the movable electrodes, torsion springs, and the like are not given.

The width X1 of the movable electrode is set, for example, in the range of 300 to 1000 μm.
The length Y1 of the movable electrode is set, for example, in the range of 300 to 2000 μm.
The width X2 of the torsion spring is set, for example, in the range of 0.5 to 5 μm.
The length Y2 of the torsion spring is set, for example, in the range of 25 to 45% of Y1.

  The distance Y3 from the center of the movable electrode to the anchor portion is set, for example, in the range of ８ to １ ／ of Y1. In other words, the distance Y4 (= 2 × Y3) between the anchor portions is set in the range of ８ (= 1/4) to ／ of Y1. Specifically, the distance Y4 between the anchor portions is set, for example, in a range of 200 to 500 μm. When Y3 (Y4) is set within the above range, the gap G1 shown in FIG. 8B can be set to 2 μm or more. In this case, even if warpage occurs, the average initial capacitance value does not change, so that it is possible to suppress a decrease in detection sensitivity to warpage. For example, if the radius of curvature is 50 nm or more, even if warpage occurs, the decrease in detection sensitivity can be kept within 10%.

Although not shown in FIG. 12, the minimum distance between the first fixed electrode (second fixed electrode) and the movable electrode is set, for example, in a range of 1 to 3 μm.
Next, a method for manufacturing the MEMS acceleration sensor according to the present embodiment will be briefly described with reference to FIGS. FIGS. 13A to 13F correspond to the cross-sectional views along the arrow 2-2 in FIG. In the present embodiment, a manufacturing method using a sacrificial film process will be described.

  First, a silicon oxide film 12 is formed on a silicon substrate 11 as shown in FIG. Next, a conductive film to be the first fixed electrode 21, the second fixed electrode 22, and the wiring layer 23 is formed on the silicon oxide film 12, and thereafter, the conductive film is patterned to form the first fixed electrode. 21, a second fixed electrode 22, and a wiring layer 23 are formed. The thickness of the conductive film is, for example, 0.6 μm.

  Next, as shown in FIG. 13B, a silicon nitride film 24 is formed on the first fixed electrode 21, the second fixed electrode 22, and the wiring layer 23. The thickness of the silicon nitride film 24 is, for example, 1 μm. Thereafter, a silicon oxide film 61 which is used as a sacrificial film and serves as an insulating film of an anchor portion is formed on the silicon nitride film 24. The thickness of the silicon oxide film 61 is, for example, 1 to 3 μm. Note that CMP (Chemical Mechanical Polishing) may be performed to sufficiently flatten the surface of the silicon oxide film 61.

  Next, as shown in FIG. 13C, a plug 62 penetrating the silicon oxide film 61 is formed. More specifically, first, a through-hole penetrating through the silicon oxide film 61 is formed by using an etching process. At this time, the silicon nitride film 24 functions as an etching stopper. The etching process is performed using, for example, RIE (Reactive Ion Etching). Next, a conductive film is formed on the entire surface so as to fill the through hole, and then the excess conductive film is removed by using CMP.

  Next, as shown in FIG. 13D, a film to be the movable electrode 26, for example, a silicon germanium film is formed on the silicon oxide film 61 by using a CVD process, and thereafter, the silicon germanium film is patterned to be movable. An electrode 26 is formed. In the drawings, the warpage of the movable electrode 26 is omitted for simplification. The patterning uses, for example, DRIE (Deep Reactive Ion Etching) which is one of RIE.

Next, as shown in FIG. 13E, an opening 25 and a plurality of through holes 27 are formed in the movable electrode 26 by using an etching process. The through-hole 27 is not formed on the portion of the anchor portion that will be the insulating film. The above etching process is performed using, for example, DRIE.
Next, a hydrogen fluoride gas (HF gas) is introduced from the opening 25 and the through hole 27 to selectively remove the silicon oxide film 13 in a portion not used as an insulating film in the anchor portion. As a result, as shown in FIG. 13F, an insulating film 61 of an anchor portion made of a silicon oxide film is formed. Thereafter, a well-known MEMS acceleration sensor manufacturing process is performed.

FIG. 14 is a plan view schematically showing a MEMS acceleration sensor according to another embodiment.
This embodiment differs from the previous embodiment in that the number of anchor portions is reduced from four to two. More specifically, the two anchor portions 52 and 54 shown in FIG. 1 are omitted.
With the decrease in the number of anchor portions, the bent portion of the first beam portion 41 and the bent portion of the second beam portion 42 have been changed. More specifically, the bent portion of the first beam portion 41 of the present embodiment does not include the portion 41c shown in FIG. In the bent portion of the second beam portion 42 of the present embodiment, the portion 42c shown in FIG. 1 is omitted. In the case of the present embodiment, the other end of the first torsion spring 31 is connected to the end of the portion 41b of the first beam portion 41, and the other end of the second torsion spring 32 is connected to the second beam portion 42. Is connected to the end of the portion 42b. Note that the number of anchor portions may be one or more.

FIG. 15 is a block diagram illustrating a MEMS acceleration sensor according to yet another embodiment.
The MEMS acceleration sensor according to the present embodiment includes a MEMS acceleration sensor 1X that detects acceleration in the X-axis direction, a MEMS acceleration sensor 1Y that detects acceleration in the Y-axis direction, and a MEMS acceleration sensor 1Z that detects acceleration in the Z-axis direction. including.

  The MEMS acceleration sensor 1X and the MEMS acceleration sensor 1Y are well-known MEMS acceleration sensors configured using, for example, a fixed electrode having a comb shape and a movable electrode having a comb shape. On the other hand, the MEMS acceleration sensor 1Z is the MEMS acceleration sensor of the embodiment shown in FIGS.

Some or all of the superordinate concept, the middle concept and the subordinate concept of the sensor of the above-described embodiment, and other embodiments not described above are described in, for example, the following supplementary notes 1-11 and 1-11. It can be expressed in any combination (excluding combinations that are clearly inconsistent).
[Appendix 1]
Board and
A first fixed electrode provided on the substrate;
A second fixed electrode provided on the substrate;
A movable electrode having an opening, disposed above the first fixed electrode and the second fixed electrode;
A first torsion spring having one end connected to the inner wall of the opening;
A first beam portion connected to the other end of the first torsion spring and having a bent portion when viewed from above the opening;
A second torsion spring having one end connected to the inner wall of the opening;
A second beam portion connected to the other end of the second torsion spring and having a bent portion when viewed from above the opening.
[Appendix 2]
The substrate has a first surface;
The first fixed electrode and the second fixed electrode are provided on the first surface,
The first fixed electrode extends along a first axis in the first plane;
The second fixed electrode extends along the first axis and is spaced apart from the first fixed electrode along a second axis in the first plane. 2. The sensor according to 1.
[Appendix 3]
The first torsion spring extends along the first axis;
3. The sensor of claim 2, wherein the second torsion spring extends along the first axis.
[Appendix 4]
The part of the inner wall of the opening to which one end of the first torsion spring is connected is opposed to the part of the inner wall of the opening to which one end of the second torsion spring 32 is connected. Sensors.
[Appendix 5]
The bent portion of the first beam portion includes a first portion parallel to the first axis and a second portion connected to the first portion and parallel to the second axis. ,
The bent portion of the second beam portion includes a third portion parallel to the first axis, and a fourth portion connected to the third portion and parallel to the second axis. 5. The acceleration sensor according to any one of supplementary notes 2 to 4.
[Appendix 6]
A first anchor portion and a second anchor portion provided on the substrate;
The first portion of the first beam portion is connected to the first anchor portion;
The sensor according to claim 5, wherein the third portion of the second beam portion is connected to the second anchor portion.
[Appendix 7]
Further comprising a third anchor portion and a fourth anchor portion provided on the substrate,
The bent portion of the first beam portion further includes a fourth portion connected to the third anchor portion,
7. The sensor according to claim 6, wherein the bent portion of the second beam portion further includes a fifth portion connected to the fourth anchor portion.
[Appendix 8]
The distance between the first anchor part and the second anchor part is not less than ４ and not more than ／ of the length of a side of the movable electrode parallel to the first axis. 8. The sensor according to 7.
[Appendix 9]
9. The sensor according to any one of supplementary notes 6 to 8, wherein a distance between the first anchor portion and the second anchor portion is not less than 200 μm and not more than 500 μm.
[Appendix 10]
The sensor according to any one of supplementary notes 1 to 9, wherein the movable electrode is warped, and a peripheral portion of the movable electrode is located above a central portion of the movable electrode.
[Appendix 11]
11. The movable electrode according to any one of supplementary notes 1 to 10, including a silicon germanium film, a silicon film, a stacked film of a silicon film and a silicon oxide film, or a stacked film of a silicon oxide film, a silicon film, and a silicon oxide film. Sensors.

  In the above-described embodiment, the sensor has been described. However, the substrate, the first fixed electrode, the second fixed electrode, the movable electrode, the first torsion spring, the first beam portion, and the second The structure may include a torsion spring and a second beam. The structure is, for example, a sensor structure in which elements such as the substrate and the fixed electrode are mechanically, electrically, or mechanically and electrically connected to each other to perform a sensor function.

  Further, the present invention may be implemented as an electric device (or an electronic device) including the sensor of the embodiment. The electric device (or the electronic device) may include, for example, an element that performs a predetermined operation and / or process (for example, information processing) based on acceleration detected by a sensor, or both. The element is implemented by, for example, hardware such as a circuit, software such as a program, or a combination of hardware and software.

  Although several embodiments of the present invention have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These new embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and their equivalents.

  G1: gap, 1X, 1Y, 1Z: MEMS acceleration sensor, 10: substrate, 10a: upper surface (first surface) of substrate, 11: silicon substrate, 12: silicon oxide film, 21: first fixed electrode, 22 ... second fixed electrode, 23 ... wiring layer, 24 ... silicon nitride film (etching stopper), 25 ... opening, 26 ... movable electrode, 27 ... through hole, 31 ... first torsion spring, 32 ... second torsion Spring, 41: first beam portion, 41a to 41c: part of first beam portion, 42: second beam portion, 42a to 42c: part of second beam portion, 51: anchor portion (first portion) Anchor part), 52 ... anchor part (third anchor part), 53 ... anchor part (second anchor part), 54 ... anchor part (fourth anchor part), 61 ... insulating film (sacrifice film), 62 …plug.

Claims (13)

Board and
A first fixed electrode provided on the substrate;
A second fixed electrode provided on the substrate;
A movable electrode having an opening, disposed above the first fixed electrode and the second fixed electrode;
A first torsion spring having one end connected to the inner wall of the opening;
A first beam portion connected to the other end of the first torsion spring and having a bent portion when viewed from above the opening;
A second torsion spring having one end connected to the inner wall of the opening;
A second beam portion connected to the other end of the second torsion spring and having a bent portion when viewed from above the opening. The substrate has a first surface;
The first fixed electrode and the second fixed electrode are provided on the first surface,
The first fixed electrode extends along a first axis in the first plane;
The second fixed electrode extends along the first axis and is spaced apart from the first fixed electrode along a second axis in the first plane. Item 2. The sensor according to Item 1. The first torsion spring extends along the first axis;
The sensor of claim 2, wherein the second torsion spring extends along the first axis.   The part of the inner wall of the opening to which one end of the first torsion spring is connected is opposed to the part of the inner wall of the opening to which one end of the second torsion spring 32 is connected. The sensor as described. The bent portion of the first beam portion includes a first portion parallel to the first axis and a second portion connected to the first portion and parallel to the second axis. ,
The bent portion of the second beam portion includes a third portion parallel to the first axis, and a fourth portion connected to the third portion and parallel to the second axis. The sensor according to claim 2. A first anchor portion and a second anchor portion provided on the substrate;
The first portion of the first beam portion is connected to the first anchor portion;
The sensor according to claim 5, wherein the third portion of the second beam is connected to the second anchor. Further comprising a third anchor portion and a fourth anchor portion provided on the substrate,
The bent portion of the first beam portion further includes a fourth portion connected to the third anchor portion,
The sensor according to claim 6, wherein the bent portion of the second beam portion further includes a fifth portion connected to the fourth anchor portion.   7. The distance between the first anchor portion and the second anchor portion is not less than 1/4 and not more than 2/3 of the length of a side of the movable electrode parallel to the first axis. Or the sensor according to 7.   The sensor according to claim 6, wherein a distance between the first anchor portion and the second anchor portion is not less than 200 μm and not more than 500 μm.   The sensor according to claim 1, wherein the movable electrode is warped, and a peripheral portion of the movable electrode is located above a central portion of the movable electrode.   11. The movable electrode according to claim 1, wherein the movable electrode includes a silicon germanium film, a silicon film, a stacked film of a silicon film and a silicon oxide film, or a stacked film of a silicon oxide film, a silicon film, and a silicon oxide film. The sensor as described.   The substrate according to claim 1, a first fixed electrode, a second fixed electrode, a movable electrode, a first torsion spring, a first beam, a second torsion spring, and a second beam. Structure including the part.   An electric device including the sensor according to claim 1.

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