JP5125327B2 - Acceleration sensor - Google Patents

Description

  The present invention relates to an acceleration sensor, and more particularly to a capacitance type acceleration sensor.

  One of the principles of an acceleration sensor that detects acceleration in the thickness direction of a conventional substrate is a method of detecting a change in capacitance due to acceleration. As an acceleration sensor according to this method, for example, an acceleration sensor having a torsion beam (flexible portion), an inertia mass body (weight), a detection frame (element), and a detection electrode (detection electrode) as main components. (Acceleration motion converter) is known (for example, refer to Patent Document 1).

  The acceleration sensor (acceleration sensing motion converter) of Patent Document 1 has one detection frame (element) having a surface facing the substrate. An inertia mass body (weight) is provided on one end of the detection frame (element). Further, the detection frame (element) is supported on the substrate so as to be able to rotate about the torsion beam (flexible portion) as a rotation axis. A detection electrode (detection electrode) for detecting the rotational displacement is provided below the detection frame (element).

  When acceleration in the substrate thickness direction is applied to the thus configured acceleration sensor (acceleration sensing motion converter), an inertial force in the substrate thickness direction acts on the inertia mass body (weight). Since the inertia mass body (weight) is provided on one end portion, that is, at a position having a deviation in the substrate plane direction from the rotation axis, this inertial force is detected as a torque around the torsion beam (flexure portion). Element). As a result, the detection frame (element) is rotationally displaced.

This rotational displacement changes the distance between the detection frame (element) and the detection electrode (detection electrode), so the capacitance of the capacitor formed by the detection frame (element) and the detection electrode (detection electrode) changes. To do. Acceleration is measured from this capacitance change.
Japanese Patent Laid-Open No. 5-133976 (page 16, FIGS. 23 and 24)

  The above-mentioned inertial mass body (weight) is always subjected to downward gravity. For this reason, the inertial mass body (weight) is in a state of being displaced below the rotation axis of the detection frame (element).

  In this state, when acceleration in the direction in the substrate plane and intersecting the rotation axis is applied to the acceleration sensor, the point of action of the inertial force on the detection frame (element) is below the rotation axis. Become. The inertial force has a component orthogonal to the rotation axis. As a result, the detection frame (element) is rotationally displaced by receiving torque around the rotation axis. That is, even when acceleration along the axis that is not detected by the acceleration sensor (acceleration on the other axis) is applied, the detection frame (element) is rotationally displaced.

  Further, even when an angular acceleration around the torsion beam (flexible portion) is applied to the acceleration sensor, the detection frame (element) rotates due to the inertial force acting on the inertial mass body (weight).

  Further, even when an angular velocity is applied to the acceleration sensor, the detection frame (element) can be rotated by the influence of the centrifugal force applied to the inertial mass body (weight).

  In the conventional acceleration sensor, the rotation of the detection frame (element) due to the other-axis acceleration, the angular acceleration, and the angular velocity is distinguished from the rotation of the detection frame (element) due to the acceleration in the substrate thickness direction as a detection target. I can't. For this reason, there has been a problem that an acceleration detection error becomes large.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a high-accuracy acceleration sensor that is less affected by other-axis acceleration, angular acceleration, and angular velocity.

  The acceleration sensor of the present invention includes a substrate, first and second torsion beams, first and second detection frames, a plurality of detection electrodes, first and second link beams, and an inertial mass body. Yes.

The first torsion beam can be twisted about the first torsion axis and is supported on the substrate. The first detection frame is supported on the substrate via the first torsion beam so as to be rotatable about the first torsion axis. The second torsion beam can be twisted about the second torsion axis and is supported by the substrate. The second detection frame is supported on the substrate via the second torsion beam so as to be rotatable about the second torsion axis. The plurality of detection electrodes are for detecting the angles of the first and second detection frames with respect to the substrate by capacitance, and are formed on the substrate so as to face the first and second detection frames, respectively. Yes. The first link beam is connected to the first detection frame on an axis that moves in a direction that intersects the first torsion axis with the first torsion axis and toward the one end side of the first detection frame. The second link beam is connected to the second detection frame on an axis obtained by shifting the second torsion axis in the direction opposite to the above direction. The inertial mass body is supported by the first and second link beams so as to be displaceable in the thickness direction of the substrate on the substrate by being connected to each of the first and second detection frames.

  According to the acceleration sensor of the present invention, the first link beam has the first detection frame on the axis that moves in the direction crossing the first torsion axis and toward the one end side of the first detection frame. It is connected to. On the other hand, the 2nd link beam is connected with the 2nd detection frame on the axis which shifted the 2nd twist axis in the direction opposite to the above-mentioned direction.

  For this reason, when the inertial mass body is displaced in the thickness direction of the substrate, the first and second detection frames are rotationally displaced in opposite directions, but the inertial mass body is inclined or displaced in the in-plane direction of the substrate. In this case, the first and second detection frames are rotationally displaced in the same direction.

  Therefore, by providing the detection electrode so as to be highly sensitive only to the rotational displacements in opposite directions of the first and second detection frames, the sensitivity to the acceleration in the direction that is not the detection target (other axis sensitivity) is suppressed, and the angular velocity is increased. And can be made less susceptible to angular acceleration.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
First, the main configuration of the acceleration sensor according to the present embodiment will be described.

FIG. 1 is a top view schematically showing a configuration of the acceleration sensor according to Embodiment 1 of the present invention. 2 is a schematic cross-sectional view taken along the line II-II in FIG. For convenience of explanation, coordinate axes X-axis, Y-axis, and Z-axis are introduced. In FIG. 1, the X axis is a positive axis in the right direction along the horizontal direction, the Y axis is a positive axis in the upward direction along the vertical direction, and the Z axis is perpendicular to the paper surface and above the paper surface. Is the positive axis. Note that the direction of the Z axis coincides with the acceleration direction to be measured by the acceleration sensor of the present embodiment.

  Referring to FIGS. 1 and 2, the acceleration sensor of the present embodiment mainly includes a substrate 1, first and second torsion beams 11 and 12, first and second detection frames 21 and 22, A plurality of detection electrodes 40, first and second link beams 31 and 32, and an inertial mass body 2 are provided.

  As the substrate 1, a silicon substrate can be used. The first and second torsion beams 11 and 12, the first and second detection frames 21 and 22, the first and second link beams 31 and 32, the inertia mass body 2, and the detection electrode 40 are made of polysilicon. A membrane can be used. This polysilicon film desirably has low stress and no stress distribution in the thickness direction.

  The first torsion beam 11 is supported on the substrate 1 by an anchor 91 so that the first torsion beam 11 can be twisted around the first torsion axis T1 along the X axis.

  The first detection frame 21 is supported by the substrate 1 via the first torsion beam 11 so as to be rotatable about the first torsion axis T1. Further, at least a part of the first detection frame 21 has conductivity.

  The second torsion beam 12 is supported on the substrate 1 by an anchor 92 so that the second torsion beam 12 can be twisted around the second torsion axis T2 along the X axis.

  The second detection frame 22 is supported by the substrate 1 via the second torsion beam 12 so as to be rotatable about the second torsion axis T2. Further, at least a part of the second detection frame 22 has conductivity.

  The plurality of detection electrodes 40 face each of the first and second detection frames 21 and 22 so that the angles of the first and second detection frames 21 and 22 with respect to the substrate 1 can be detected by electrostatic capacitance. As described above, the insulating film 3 is formed on the substrate 1. The insulating film 3 is preferably a low stress silicon nitride film or silicon oxide film.

  The first link beam 31 has a first detection on an axis L1 that is translated by an offset e1 in a direction in which the first torsion axis T1 intersects the first torsion axis T1 and toward the one end side of the first detection frame 21. It is connected to the frame 21. That is, the absolute value of the offset e1 is a dimension between the first torsion axis T1 and the first link beam 31, and the direction intersects the first torsion axis T1 and is a direction from the first torsion axis T1 toward the axis L1. It is.

  The second link beam 32 is connected to the second detection frame 22 on the axis L2 in which the second torsion axis T2 is shifted parallel to the direction opposite to the above-described direction, that is, the offset e2 in the direction opposite to the offset e1 direction. . That is, the absolute value of the offset e2 is a dimension between the second torsion axis T2 and the second link beam 32, and the direction thereof is opposite to the offset e1.

  The inertial mass body 2 can be displaced in the thickness direction of the substrate 1 on the substrate 1 by being connected to each of the first and second detection frames 21 and 22 by the first and second link beams 31 and 32, respectively. It is supported by.

  Next, the details of the configuration of the detection electrode 40 and the principle that the detection electrode 40 can detect the angles of the first and second detection frames 21 and 22 relative to the substrate 1 will be described.

  The detection electrode 40 has a first detection electrode 41 facing the first detection frame 21. The first detection electrode 41 includes first detection electrodes 41a and 41b so as to sandwich the first twist axis T1. The first detection electrode 41a is located on the outer circumference side (upper side in FIG. 1) of the acceleration sensor, and the first detection electrode 41b is located on the inner circumference side (center side in FIG. 2) of the acceleration sensor. The first detection electrodes 41a and 41b are provided so as to sandwich the first torsion axis T1.

  When the first detection frame 21 is rotated around the first torsion beam 11, the back surface (the surface facing the first detection electrode 41) of the first detection frame 21 approaches one of the first detection electrodes 41a and 41b. And move away from the other. Therefore, the capacitance generated when the first detection frame 21 faces the first detection electrode 41a and the capacitance formed when the first detection frame 21 faces the first detection electrode 41b. The angle of the first detection frame 21 with respect to the substrate 1 can be detected.

  The detection electrode 40 has a second detection electrode 42 facing the second detection frame 22. The second detection electrode 42 includes second detection electrodes 42a and 42b so as to sandwich the second torsion axis T2. The second detection electrode 42a is located on the outer periphery side (lower side in FIG. 1) of the acceleration sensor, and the second detection electrode 42b is located on the inner periphery side (center side in FIG. 1) of the acceleration sensor. The second detection electrodes 42a and 42b are provided so as to sandwich the second torsion axis T2.

  When the second detection frame 22 is rotated around the second torsion beam 12, the back surface of the second detection frame 22 (the surface facing the detection electrode 42) approaches one of the second detection electrodes 42a and 42b, Move away from the other. For this reason, the electrostatic capacitance generated when the second detection frame 22 faces the second detection electrode 42a and the electrostatic capacitance formed when the second detection frame 22 faces the second detection electrode 42b. Is detected, the angle of the second detection frame 22 with respect to the substrate 1 can be detected.

  Preferably, the first and second torsion beams 11 and 12 and the first and second link beams 31 and 32 are arranged so that the offsets e1 and e2 are equal in opposite directions.

  More preferably, the planar layout of the acceleration sensor has a structure symmetrical with respect to a center line B extending in a direction parallel to the first and second torsion axes T1 and T2, and the center of gravity G of the inertial mass body 2 Is located on the center line B.

  The plane layout of the acceleration sensor has a symmetrical structure with respect to the center line A extending in the direction intersecting the first and second torsion axes T1 and T2, and the center of gravity G of the inertial mass body 2 is the center. Located on line A.

Next, the principle of measuring the acceleration of the acceleration sensor according to the present embodiment will be described.
FIG. 3 is a cross-sectional view schematically showing a state in which acceleration is applied upward along the film thickness direction of the substrate with respect to the acceleration sensor according to the first embodiment of the present invention. 3 is the same as that in FIG. Further, in FIG. 3, the anchors 91 and 92 are not shown for easy understanding of the drawing.

Referring to FIG. 3, when an acceleration az in the upward direction along the film thickness direction of the substrate, that is, in the positive direction of the Z axis (upward in the figure) is applied to the acceleration sensor, the inertial mass body 2 is moved to the initial position by the inertial force. It is displaced so as to sink in the negative direction of the Z-axis (downward in the figure) from the position indicated by the broken line in the figure. The first and second link beams 31 and 32 connected to the inertial mass body 2 are also displaced integrally with the inertial mass body in the negative direction of the Z-axis (downward in the figure).

  Due to the displacement of the first link beam 31, the first detection frame 21 receives a force in the negative direction of the Z-axis (downward in the figure) at the portion of the axis L1. Since the axis L1 is in a position translated from the first torsion axis Tl by the offset e1, a torque acts on the first detection frame 21. As a result, the first detection frame 21 is rotationally displaced.

  Further, due to the displacement of the second link beam 32, the second detection frame 22 receives a force in the negative direction of the Z axis (downward in the figure) at the portion of the axis L2. Since the axis L2 is in a position translated from the second torsion axis T2 by the offset e2, torque acts on the second detection frame 22. As a result, the second detection frame 22 is rotationally displaced.

  Since the offsets e1 and e2 are opposite to each other, the first detection frame 21 and the second detection frame 22 rotate in opposite directions. That is, the upper surface of the first detection frame 21 faces one end side (right side in FIG. 3) of the acceleration sensor, and the upper surface of the second detection frame 22 faces the other end side (left side in FIG. 3) of the acceleration sensor. Further, the first and second detection frames 21 and 22 are rotationally displaced.

Along with this rotational displacement, the capacitance C _{1a of the} capacitor C ₁ a constituted by the first detection frame 21 and the first detection electrode 41 a increases, and is constituted by the first detection frame 21 and the first detection electrode 41 b. The capacitance C _{1b of the} capacitor C _1b decreases. Further, the capacitance C _2a of the capacitor C2a constituted by the second detection frame 22 and the second detection electrode 42a increases, and the capacitance of the capacitor C2b constituted by the second detection frame 22 and the second detection electrode 42b increases. The capacity C _2b decreases.

Referring to FIG. 4, capacitors C1a and C2a are connected in parallel, and capacitors C1b and C2b are connected in parallel. These two parts connected in parallel are further connected in series. The thus formed circuit of a capacitor C1a, the end portion of C2a side constant potential V _d is applied, the capacitor C1b, an end portion of C2b side is grounded. The series connection portion is provided with a terminal, and the output potential _Vout of this terminal can be measured. This output potential V _out has the following value.

Since the constant potential V _d is a constant value, by measuring the output potential V _out ,

You can know the value of.
The value of this equation (2) decreases when the inertial mass body 2 sinks as shown in FIG. Further, when an acceleration in the direction opposite to the acceleration az (FIG. 3) is applied to the acceleration sensor, the inertial mass body 2 is displaced upward in the thickness direction of the substrate 1, and the value of the equation (2) increases. Therefore, the displacement of the inertial mass body 2 in the thickness direction of the substrate 1 can be detected by measuring the output potential _Vout, and the acceleration az in the Z-axis direction can be detected based on the detection result.

  Next, an example in which a motion other than the acceleration in the Z direction is applied to the acceleration sensor of the present embodiment will be described.

  5 and 6 are cross-sectional views schematically showing a state in which negative angular acceleration in the X-axis direction is applied around the center of gravity of the inertial mass body with respect to the acceleration sensor, and the cross-sectional positions are the same as those in FIG. . In FIG. 5, the first and second detection frames 21 and 22, the anchors 91 and 92, and the detection electrode 40 are omitted for easy understanding of the drawing. In FIG. 6, the anchors 91 and 92 are omitted.

  Referring to FIG. 5, when inertial mass body 2 receives negative angular acceleration aω in the X-axis direction around center of gravity G, inertia mass body 2 is opposite to angular acceleration aω from the initial position (the position indicated by the broken line in the figure) due to the moment of inertia. It is inclined to rotate in the direction (direction of arrow R in the figure).

  Referring to FIG. 6, as the inertial mass body 2 is inclined, the first detection frame 21 is lifted by the portion of the axis L1 of the first link beam 31 and rotated about the first torsion axis T1. The second detection frame 22 is pushed down at the portion of the axis L2 of the second link beam 32 and rotated around the second torsion axis T2.

As the first and second detection frames 21 and 22 rotate, the capacitance C _{1a of the} capacitor C1a formed by the first detection frame 21 and the first detection electrode 41a decreases, and the first detection frame 21 The capacitance C _{1b of the} capacitor C1b formed by the first detection electrode 41b increases. Further, the capacitance C _2a of the capacitor C2a constituted by the second detection frame 22 and the second detection electrode 42a increases, and the capacitance of the capacitor C2b constituted by the second detection frame 22 and the second detection electrode 42b increases. The capacity C _2b decreases.

Referring to equation (2), when the above-described change in capacitance occurs, the decrease in capacitance C _1a and the increase in C _2a cancel each other in the left side denominator, and the increase in C _{1b in} the left side numerator. The decrease in C _2b is offset. For this reason, the influence of the angular acceleration aω on the output potential V _out is suppressed.

  FIG. 7 shows a state in which an angular velocity having a positive component in the Z-axis direction and a negative component in the Y-axis direction is applied around the center of gravity of the inertial mass body with respect to the acceleration sensor. In FIG. 7, the first and second detection frames 21 and 22, the anchors 91 and 92, and the detection electrode 40 are omitted for easy understanding of the drawing.

  Referring to FIG. 7, the centrifugal force fc accompanying the rotation of the angular velocity ω acts on the inertial mass body 2. For this reason, the inertial mass body 2 is tilted from the initial position (the position of the broken line in the figure) to the direction in which the end of the inertial mass body 2 moves away from the rotation axis of the angular velocity ω (the direction of the arrow R in the figure). To do.

The inclination of the inertial mass body 2 is the same as that when the angular acceleration aω described above is applied. For this reason, the influence which angular velocity (omega) has on output potential _Vout is also suppressed by the same principle.

  Next, a detection error when an acceleration of another axis is applied to the acceleration sensor of the present embodiment will be described including the influence of gravity.

FIG. 8 is a cross-sectional view schematically showing a state in which negative acceleration in the Y-axis direction is applied to the acceleration sensor, and the cross-sectional position is the same as FIG. In FIG. 8, the first and second detection frames 21 and 22, the anchors 91 and 92, and the detection electrode 40 are omitted for easy understanding of the drawing.

  Referring to FIG. 8, a negative force in the Z-axis direction acts on the inertial mass body 2 as gravity, and the inertial mass body 2 moves downward (in the direction of the Z-axis in the drawing) from the initial position (the position of the broken line in the drawing). It is in a state of sinking in the negative direction.

  Under this state, when acceleration ay is applied to the acceleration sensor in the negative direction of the Y axis, an inertia force in the positive direction of the Y axis is applied to the inertial mass body 2. This inertial force is transmitted to each of the first and second detection frames 21 and 22 at portions on the axes L1 and L2 of the first and second link beams 31 and 32, respectively.

  The height of the axis L1 from the substrate 1 is lower than the first torsion axis T1 due to the influence of gravity. For this reason, the force transmitted to the portion of the axis L1 acts on the first detection frame 21 as a torque around the first torsion axis T1.

  Further, the height of the axis L2 from the substrate 1 is lower than the second torsion axis T2 due to the influence of gravity. For this reason, the force transmitted to the portion of the axis L2 acts on the second detection frame 22 as a torque around the second torsion axis T2.

  Here, the torques around the first and second torsion axes T1 and T2 both have an action point below the first and second torsion axes T1 and T2. Further, both forces acting on the action point are positive in the Y-axis direction. As a result, the rotational displacement R1 of the first detection frame 21 and the rotational displacement R2 of the second detection frame 22 are in the same direction.

As a result of the rotational displacement R1, the capacitance C _1a of the capacitor C1a formed by the first detection frame 21 and the first detection electrode 41a decreases, and is configured by the first detection frame 21 and the first detection electrode 41b. the capacitance C _1b of the capacitor C1b is increased that. Further, as the influence of the rotational displacement R2, the capacitance C _2a of capacitor C2a formed by a detection electrode 42a and the second detection frame 22 is increased, the capacitor formed by the detection electrodes 42b and the second detection frame 22 the capacitance C _2b of C2b is reduced.

Referring to equation (2), when the above-described change in capacitance occurs, the decrease in capacitance C _1a and the increase in C _2a cancel each other in the left side denominator, and the increase in C _{1b in} the left side numerator. The decrease in C _2b is offset. For this reason, the influence of the acceleration ay in the Y-axis direction on the output potential _Vout measured for detecting the acceleration in the Z-axis direction is suppressed.

  Then, the manufacturing method of the acceleration sensor of this Embodiment is demonstrated. 9 to 13 are schematic cross-sectional views sequentially illustrating first to fifth steps of the method for manufacturing the acceleration sensor according to the first embodiment of the present invention, and the cross-sectional positions thereof correspond to the cross-sectional positions of FIG. .

Referring to FIG. 9, an insulating film 3 is deposited on a substrate 1 made of silicon by LPCVD (Low Pressure Chemical Vapor Deposition) method. As the insulating film 3, a low-stress silicon nitride film or silicon oxide film is suitable. A conductive film made of, for example, polysilicon is deposited on the insulating film 3 by LPCVD. Subsequently, the conductive film is patterned to form the detection electrode 40. Thereafter, a PSG (Phosphosilicate Glass) film 101 is deposited on the entire substrate 1.

Referring mainly to FIG. 10, a portion of PSG film 10 where anchors 91 and 92 (FIG. 2) are formed is formed.
1 is selectively removed.

  Referring to FIG. 11, a polysilicon film 102 is deposited on the entire substrate 1. Subsequently, a CMP (Chemical Mechanical Polishing) process is performed on the surface.

  Referring to FIG. 12, the surface of polysilicon film 102 is planarized by the CMP process.

  Referring to FIG. 13, selective etching is performed on a portion of polysilicon film 102 above the upper surface of PSG film 101. As a result, the inertial mass body 2, the first and second link beams 31, 32, the first and second detection frames 21, 22, the first and second torsion beams 11, 12, and the anchors 91, 92 are obtained. Are collectively formed. Thereafter, the PSG film 101 is removed by etching, and the acceleration sensor of the present embodiment shown in FIG. 2 is obtained.

According to the present embodiment, as shown in FIG. 1, the acceleration sensor has a planar layout in which the offsets e1 and e2 are opposite to each other. Therefore, when an angular acceleration aω is applied to the acceleration sensor as shown in FIG. 5, in the electric circuit shown in FIG. 4, the capacitance change cancels between the capacitors C1a and C2a and between the capacitors C1b and C2b. Is done. Therefore, fluctuations in the value shown in Equation (2) are suppressed. That is, the influence of the angular acceleration aω on the output potential V _out can be suppressed. Therefore, when detecting the acceleration az from the output potential _Vout, it is possible to suppress the occurrence of a detection error due to the angular acceleration aω.

Also, as shown in FIG. 7, even when the angular velocity ω is added to the acceleration sensor, the fluctuation of the value shown in the equation (2) is suppressed by canceling the capacitance change similar to the case where the angular acceleration aω is added. Is done. That is, the influence of the angular velocity ω on the output potential V _out can be suppressed. Therefore, when the acceleration az is detected from the output potential _Vout, it is possible to suppress an error in the measurement result due to the angular velocity ω.

In addition, when acceleration ay in a direction other than the film thickness direction of the substrate 1 is added as shown in FIG. 8, the capacitance change cancels the same as when the angular acceleration aω and the angular velocity ω are added. The fluctuation of the value shown in (2) is suppressed. That is, the influence of the acceleration ay in a direction other than the thickness direction of the substrate 1 to be measured on the output potential _Vout can be suppressed. Therefore, when the acceleration az in the thickness direction of the substrate is detected by the output potential _Vout, it is possible to suppress an error in the measurement result due to the acceleration ay in the other direction.

  Further, as shown in FIGS. 12 and 13, the inertial mass body 2 serving as a movable part, the first and second link beams 31, 32, the first and second detection frames 21, 22, and the first and first Two torsion beams 11 and 12 are collectively formed from films made of the same material. Therefore, since there is no joint part of different materials in the movable part, there is no occurrence of distortion caused by the difference in thermal expansion coefficient of different materials. For this reason, the temperature dependence of the acceleration sensor can be suppressed.

  In the present embodiment, preferably, offsets e1 and e2 shown in FIG. 1 have the same absolute value. Further, the first and second torsion axes T1 and T2 shown in FIG. 1 are parallel to each other. Therefore, when the inertial mass body 2 is tilted as shown by the arrow R in FIG. 5, the rotational displacement amounts of the first and second detection frames 21 and 22 are equal as shown in FIG. Therefore, the capacitance changes of the capacitors C1a, C1b, C2a and C2b shown in FIG. 4 are offset more accurately. For this reason, the error of the acceleration sensor can be further suppressed.

(Embodiment 2)
14 and 15 are a top view and a cross-sectional view schematically showing the configuration of the acceleration sensor according to the second embodiment of the present invention. FIG. 15 is a sectional view taken along line XV-XV in FIG.

  Referring to FIGS. 14 and 15, in the acceleration sensor of the present embodiment, actuation electrode 5 is formed on substrate 1 so as to face inertial mass body 2.

  In addition, since the structure other than this of this Embodiment is the same as that of the structure of Embodiment 1 mentioned above, the same code | symbol is attached | subjected about the same element and the description is abbreviate | omitted.

  According to the present embodiment, by applying a voltage between the actuation electrode 5 and the inertial mass body 2, the static electricity that pulls the inertial mass body 2 toward the substrate 1 as shown by the arrow in FIG. 15. Can generate power. That is, the inertial mass body 2 can be electrostatically driven in the film thickness direction of the substrate 1. By this electrostatic drive, a displacement similar to the displacement of the inertial mass body 2 when the acceleration sensor is applied with the acceleration az in the film thickness direction of the substrate 1 can be generated. Therefore, the acceleration sensor can be provided with a function of self-diagnosis whether the sensor has failed without actually applying acceleration az to the acceleration sensor.

(Embodiment 3)
FIG. 16 is a top view schematically showing a configuration of the acceleration sensor according to the third embodiment of the present invention. Referring to FIG. 16, the acceleration sensor according to the present embodiment has an anchor 90 provided on substrate 1 and support beam 4.

  One end of the support beam 4 is supported on the substrate 1 by an anchor 90. The other end of the support beam 4 supports the inertial mass body 2.

  The support beam 4 includes a first support beam 4X and a second support beam 4Y. The first support beam 4X has a shape that can be easily elastically deformed in the Z-axis direction and hardly elastically deformed in the X-axis direction. The second support beam 4Y has a shape that can be easily elastically deformed in the Z-axis direction and hardly elastically deformed in the Y-axis direction. For this reason, the support beam 4 as a whole can be easily elastically deformed in the Z-axis direction and hardly elastically deformed in the XY plane direction.

  In addition, since the structure other than this of this Embodiment is the same as that of the structure of Embodiment 1 mentioned above, the same code | symbol is attached | subjected about the same element and the description is abbreviate | omitted.

  According to the present embodiment, the inertial mass body 2 is supported on the substrate 1 by the support beam 4 that is difficult to elastically deform in the XY in-plane direction. Thereby, the displacement of the inertial mass body 2 when acceleration in the XY plane direction (other-axis acceleration) is applied to the acceleration sensor can be suppressed. Therefore, it is possible to reduce the sensitivity to other axis acceleration (other axis sensitivity).

(Embodiment 4)
FIG. 17 is a top view schematically showing a configuration of the acceleration sensor according to the fourth embodiment of the present invention. In addition to the configuration of the acceleration sensor of the second embodiment, the acceleration sensor of the present embodiment further includes third and fourth torsion beams 13 and 14, third and fourth detection frames 23 and 24, and a plurality of first sensors. The third and fourth detection electrodes 43 and 44 and the third and fourth link beams 33 and 34 are provided.

  The third torsion beam 13 is supported on the substrate 1 by an anchor 93 so that it can be twisted around the third torsion axis T3 along the Y axis.

The third detection frame 23 is supported by the substrate 1 via the third torsion beam 13 so as to be rotatable about the third torsion axis T3. Further, at least a part of the third detection frame 23 has conductivity.

  The fourth torsion beam 14 is supported on the substrate 1 by an anchor 94 so that it can be twisted around a fourth torsion axis T4 along the Y axis.

  The fourth detection frame 24 is supported on the substrate 1 via the fourth torsion beam 14 so as to be rotatable about the fourth torsion axis T4. Further, at least a part of the fourth detection frame 24 has conductivity.

  The plurality of third detection electrodes 43 have third detection electrodes 43a and 43b facing the third detection frame 23 so that the angle of the third detection frame 23 with respect to the substrate 1 can be detected. The plurality of fourth detection electrodes 44 include fourth detection electrodes 44a and 44b facing the fourth detection frame 24 so that the angle of the fourth detection frame 24 with respect to the substrate 1 can be detected.

  The third link beam 33 has a third detection on an axis L3 that is translated by an offset e3 in a direction in which the third torsion axis T3 intersects the third torsion axis T3 and toward the one end side of the third detection frame 23. It is connected to the frame 23. That is, the absolute value of the offset e3 is a dimension between the third torsion axis T3 and the third link beam 33, and the direction intersects the third torsion axis T3 and is a direction from the third torsion axis T3 toward the axis L3. It is.

  The fourth link beam 34 is connected to the fourth detection frame 24 on the axis L4 in which the fourth torsion axis T4 is shifted in parallel with the direction opposite to the above-described direction, that is, the offset e4 in the direction opposite to the direction of the offset e3. . That is, the absolute value of the offset e4 is a dimension between the fourth torsion axis T4 and the fourth link beam 34, and the direction thereof is opposite to the offset e3.

  The inertial mass body 2 can be displaced in the thickness direction of the substrate 1 on the substrate 1 by being connected to each of the third and fourth detection frames 23 and 24 by the third and fourth link beams 33 and 34, respectively. It is supported by.

  The third torsion beam 13, the third detection frame 23, the third link beam 33, and the plurality of third detection electrodes 43 are the first torsion beam 11, the first detection frame 21, the first link beam 31, and the plurality of first detection electrodes. It may be formed in the same shape as the electrode 41 and in an orientation rotated by 90 ° around the Z axis.

  The fourth torsion beam 14, the fourth detection frame 24, the fourth link beam 34, and the plurality of fourth detection electrodes 44 include the second torsion beam 12, the second detection frame 22, the second link beam 32, and the plurality of detections. It may be formed in the same shape as the electrode 42 and in an orientation rotated by 90 ° around the Z axis.

  In addition, since the structure other than this of this Embodiment is the same as that of the structure of Embodiment 2 mentioned above, the same code | symbol is attached | subjected about the same element and the description is abbreviate | omitted.

  According to the present embodiment, the third and fourth link beams 33 and 34 are formed along the Y-axis direction (vertical direction in the figure) as shown in FIG. For this reason, the displacement of the inertial mass body 2 in the Y-axis direction can be suppressed. Therefore, it is possible to suppress measurement errors caused by the acceleration in the Y-axis direction (vertical direction in the figure) being applied and the inertial mass body 2 being displaced in the Y-axis direction.

(Embodiment 5)
FIG. 18 is a top view schematically showing a configuration of the acceleration sensor according to the fifth embodiment of the present invention.

  In the acceleration sensor of the second embodiment described above, the inertial mass body 2 is disposed on the outer peripheral side of the acceleration sensor, and the first and second detection frames 21 and 22 are disposed on the inner side thereof. On the other hand, the acceleration sensor of the present embodiment is different from that of the second embodiment in that the first and second detection frames 21R and 22R are arranged on the outer peripheral side of the acceleration sensor, and the inertial mass body 2R is arranged on the inner side. It is different from the acceleration sensor.

  Along with this difference in arrangement, the arrangement of the detection electrode 40R and the actuation electrode 5R in the present embodiment is also different from that in the first embodiment. That is, in the acceleration sensor of the present embodiment, the detection electrode 40R is disposed on the outer peripheral side of the substrate 1, and the actuation electrode 5R is disposed on the inside thereof.

  The detection electrode 40R includes first and second detection electrodes 41R and 42R facing the first and second detection frames 21R and 22R, respectively. The first detection electrode 41R has first detection electrodes 41aR and 41bR that are separated from each other by a first twist axis T1 as a planar layout. The second detection electrode 42R includes second detection electrodes 42aR and 42bR that are separated from each other by a second torsion axis T2 as a planar layout.

  The first and second detection electrodes 41bR and 42bR are arranged on the center side of the substrate 1, and the first and second detection electrodes 41aR and 42aR are arranged on the peripheral side of the substrate 1. Each of the first and second detection electrodes 41bR and 42bR on the center side is formed to avoid a position directly below the inertial mass body 2R. As a result, each of the first and second detection electrodes 41bR and 42bR is divided into two regions. The first and second detection electrodes 41aR and 42aR have the same shape as the first and second detection electrodes 41bR and 42bR.

  In addition, since the structure other than this of this Embodiment is the same as that of the structure of Embodiment 2 mentioned above, the same code | symbol is attached | subjected about the same element and the description is abbreviate | omitted.

  According to the present embodiment, detection electrode 40R is provided on the outer peripheral side of inertial mass body 2R. For this reason, the wiring from the detection electrode 40R can be easily performed without passing below the inertial mass body 2R. Therefore, it is possible to suppress the formation of a parasitic capacitance between the wiring for the detection electrode 40R and the inertia mass body 2R, and it is possible to detect the acceleration az with higher accuracy.

  Further, in the planar layout, a gap S exists between the first detection frame 21R and the second detection frame 22R. For this reason, by providing a wiring for the actuation electrode 5R in the space S, it is possible to suppress the formation of parasitic capacitance between the wiring and the first and second detection frames 21R and 22R. Can do. Therefore, it is possible to detect acceleration with higher accuracy.

(Embodiment 6)
FIG. 19 is a cross-sectional view schematically showing a configuration of the acceleration sensor according to the sixth embodiment of the present invention. Referring to FIG. 19, the acceleration sensor according to the present embodiment has a cap 6, first and second detection electrodes 41M and 42M, and an anchor 90 in addition to the configuration of the second embodiment. doing.

The cap 6 is made of glass, for example, and is supported on the substrate 1 by an anchor 90. As a method for bonding the cap 6, a method capable of strong bonding such as anodic bonding is desirable. The cap 6 covers the first and second detection frames 21 and 22 formed on the substrate 1 and the inertial mass body 2.

  Preferably, the cap 6 seals the first and second detection frames 21 and 22 and the inertial mass body 2 on the substrate 1.

  Each of the first and second detection electrodes 41M and 42M is formed on the back surface side (side facing the substrate 1) of the cap 6 so as to face each of the first and second detection frames 21 and 22. . The first detection electrode 41M includes a first detection electrode 41aM provided above the first detection electrode 41a and a first detection electrode 41bM provided above the first detection electrode 41b. The second detection electrode 42M includes a second detection electrode 42aM provided above the second detection electrode 42a and a second detection electrode 42bM provided above the second detection electrode 42b.

  The first detection electrode 41aM and the first detection frame 21 face each other to form a capacitor C1aM. Further, the first detection electrode 41bM and the first detection frame 21 face each other to form a capacitor C1bM. Further, the second detection electrode 42aM and the second detection frame 22 face each other to form a capacitor C2aM. Further, the second detection electrode 42bM and the second detection frame 22 face each other to form a capacitor C2bM.

  The capacitors described above and the capacitors C1a, C1b, C2a, and C2b described in the first embodiment constitute the electric circuit of FIG.

  In addition, since the structure other than this of this Embodiment is the same as that of the structure of Embodiment 2 mentioned above, the same code | symbol is attached | subjected about the same element and the description is abbreviate | omitted.

  According to the present embodiment, as shown in FIG. 19, the structure part of the acceleration sensor (the part of the first and second detection frames 21 and 22 and the inertial mass body 2) is covered by the cap 6. And preferably sealed. For this reason, it can suppress that impurities, such as garbage and a water droplet, penetrate | invade into a structure part. Therefore, the environmental resistance of the acceleration sensor is improved.

The first and second detection electrodes 41M and 42M are formed not only on the first and second detection electrodes 41 and 42 on the substrate 1 but also on the cap 6. For this reason, as shown in FIG. 20, the electrostatic capacitance between the detection terminal of the output potential _Vout and the ground portion, and between the terminal to which the constant potential _Vd is applied and the ground portion are set as shown in FIG. Compared to the case, it can be almost doubled. Thereby, the detection sensitivity of the acceleration sensor is improved.

  In the description of each of the above embodiments, a surface-processed acceleration sensor formed using, for example, a polysilicon film on a silicon substrate has been described. The present invention is not limited to this, and may be a bulk type acceleration sensor.

  In the case of a bulk type acceleration sensor, a glass substrate can be used as the substrate 1. Further, as the first to fourth detection electrodes 41, 42, 43, and 44, electrodes made of a metal thin film such as an Au (gold) thin film formed on a Cr (chromium) base can be used. In addition, the detection frames 21, 22, 23, 24, and the like can be formed of single crystal silicon.

(Embodiment 7)
In the description of the first to sixth embodiments described above, the first and second torsion beams 11 and 12 are ideal torsion beams and have been described under the approximation that they do not perform displacement other than torsional displacement. Strictly speaking, the first and second torsion beams 11 and 12 generally have a cantilever displacement in addition to the torsion displacement. That is, the first torsion beam 11 is displaced in the Z-axis direction on the first detection frame 21 side with the anchor 91 side as a fixed point, and the second torsion beam 12 is displaced on the anchor 92 side in the Z-axis direction. It is displaced to. In the description of the seventh to ninth embodiments, the above-described cantilever displacement of the first and second torsion beams 11 and 12 will be described.

  FIG. 21 is a top view schematically showing a configuration of the acceleration sensor according to the seventh embodiment of the present invention. FIG. 22 is a partial cross-sectional view schematically showing a state in which acceleration is applied upward along the film thickness direction of the substrate with respect to the acceleration sensor according to the seventh embodiment of the present invention. 22 is a position along the line XXII-XXII in FIG. Further, in FIG. 22, the anchor is not shown for easy understanding of the drawing. Further, the position of the second torsion axis T2 in the Z-axis direction in FIG. 22 corresponds to the above-mentioned cantilever displacement of the second torsion beam 12.

  Referring to FIGS. 21 and 22, as a result of the first torsion beam 11 being cantilever-displaced as described above in accordance with the change in acceleration az, the first rotation axis that is the axis of rotation of the first detection frame 21 is obtained. CR1 is displaced from the first torsion axis T1. For the same reason, the second rotation axis CR2, which is the rotation axis of the second detection frame 22, is shifted from the second torsion axis T2.

The first detection electrodes 41a and 41b are provided symmetrically with each other in plan view (plan view in the same direction as FIG. 21) with respect to the first rotation axis CR1. The second detection electrodes 42a and 42b are provided symmetrically with each other in plan view with respect to the second rotation axis CR2. Due to this symmetry, as shown in FIG. 23, regarding the output change ΔV _out of the output potential V _out , the graph of the output change ΔV _{out in} the region where the acceleration az is positive and the output change ΔV _out in the region where the acceleration az is negative. Symmetry between _out graphs is improved.

  In addition, since the structure other than this of this Embodiment is the same as that of the structure of Embodiment 1 mentioned above, the same code | symbol is attached | subjected about the same element and the description is abbreviate | omitted.

  Next, the configuration of the acceleration sensor in the comparative example of the present embodiment will be described. FIG. 24 is a top view schematically showing a configuration of the acceleration sensor in the comparative example of the seventh embodiment of the present invention. FIG. 25 is a partial cross-sectional view schematically showing a state when acceleration is applied upward along the film thickness direction of the substrate with respect to the acceleration sensor in the comparative example of the seventh embodiment of the present invention. The cross-sectional position in FIG. 25 is a position along the line XXV-XXV in FIG. In FIG. 25, the anchor is not shown in order to make the drawing easy to see. Further, the position in the Z-axis direction of the second torsion axis T2 in FIG. 25 corresponds to the above-described cantilever displacement of the second torsion beam 12.

24 and 25, the first detection electrodes 41a and 41b of the present comparative example are provided symmetrically with each other in plan view (plan view in the same direction as FIG. 24) with respect to the first twist axis T1. ing. The second detection electrodes 42a and 42b are provided symmetrically with each other in plan view with respect to the second torsion axis T2. Here, the position of the second torsion axis T2 and the second rotation axis CR2 is shifted. Therefore, the second detection electrodes 42a and 42b are asymmetric with each other in plan view with respect to the second rotation axis CR2. Similarly, the first detection electrodes 41a and 41b are asymmetric with each other in plan view with respect to the first rotation axis CR1. Due to this asymmetry, as shown in FIG. 26, regarding the output change ΔV _out of the output potential V _out , the graph of the output change ΔV _{out in} the region where the acceleration az is positive and the output change ΔV _out in the region where the acceleration az is negative. Symmetry with the _out graph is worse.

According to the present embodiment, as shown in FIGS. 21 and 22, each of the first and second detection electrodes 41 and 42 is symmetrical in plan view with respect to each of the first and second rotation axes CR1 and CR2. Since it is provided, as shown in FIG. 23, an output change ΔV _out having a good symmetry between the positive acceleration region and the negative acceleration region can be obtained.

(Embodiment 8)
In the description of the seventh embodiment, the description has been given under the approximation that the first and second rotation axes CR1 and CR2 are at fixed positions. Strictly speaking, the positions of the first and second rotation axes CR1 and CR2 have a frequency dependency with respect to acceleration. In the description of the present embodiment, the description will be made in consideration of this frequency dependency.

  FIG. 27 is a top view schematically showing a configuration of the acceleration sensor according to the eighth embodiment of the present invention. FIG. 28 is a partial cross-sectional view schematically showing a state in which acceleration is applied upward along the film thickness direction of the substrate with respect to the acceleration sensor according to the eighth embodiment of the present invention. 28 is a position along the line XXVIII-XXVIII in FIG. In FIG. 28, the anchor is not shown in order to make the drawing easy to see. Further, the position of the second torsion axis T2 in the Z-axis direction in FIG. 28 corresponds to the above-mentioned cantilever displacement of the second torsion beam 12.

  Referring to FIGS. 27 and 28, the center of gravity F1 of the first detection frame 21 of the acceleration sensor of the present embodiment is located on the first rotation axis CR1. The center of gravity F2 of the second detection frame 22 is located on the second rotation axis CR2.

  In addition, since the structure other than this of this Embodiment is the same as that of the structure of Embodiment 7 mentioned above, the same code | symbol is attached | subjected about the same element and the description is abbreviate | omitted.

  According to the present embodiment, the center of gravity of each of the first and second detection frames 21 and 22 is located on each of the first and second rotation axes CR1 and CR2. Thereby, the frequency dependence of the position of 1st and 2nd rotating shaft CR1, CR2 can be suppressed. Therefore, the acceleration sensor according to the present embodiment can stably have the effects described in the seventh embodiment over a wide frequency range.

(Embodiment 9)
FIG. 29 is a top view schematically showing a configuration of the acceleration sensor according to the ninth embodiment of the present invention. FIG. 30 is a partial cross-sectional view schematically showing a state when acceleration is applied upward along the film thickness direction of the substrate with respect to the acceleration sensor according to the ninth embodiment of the present invention. 30 is a position along the line XXX-XXX in FIG. Further, in FIG. 30, the anchor is not shown for easy understanding of the drawing.

  Referring to FIGS. 29 and 30, the first and second torsion axes T1 and T2 of the acceleration sensor of the present embodiment are the first and second rotation axes CR1 and CR2, respectively.

  In addition, since the structure other than this of this Embodiment is the same as that of the structure of Embodiment 7 mentioned above, the same code | symbol is attached | subjected about the same element and the description is abbreviate | omitted.

According to the present embodiment, the first and second detection electrodes 41 and 42 are provided so as to be symmetrical in plan view with respect to the first and second torsion axes T1 and T2, respectively. The second detection electrodes 41 and 42 can be provided symmetrically in plan view with respect to the first and second rotation axes CR1 and CR2. Therefore, the first detection electrodes 41 having a large area can be provided on both sides of the axis in the plan view of the torsion axis T1, and the second detection electrodes having a large area on both sides of the axis in the plan view of the torsion axis T2. 42 can be provided. Therefore, the capacitances of the capacitors C1a, C1b, C2a, and C2b can be increased, so that the rate of change in capacitance can be detected with high accuracy. For this reason, since the rotation angles of the first and second detection frames 21 and 22 can be detected with high accuracy, the acceleration can be measured with high accuracy.

  In the configuration shown in FIG. 21 (Embodiment 7), unlike the present embodiment, the first and second torsion shafts T1 and T2 are offset from the first and second rotation shafts CR1 and CR2, respectively. . In this case, in order to maintain the symmetry described in the seventh embodiment, the regions NE (1) on the respective sides of the first and second rotation axes CR1 and CR2 of the first and second torsion axes T1 and T2 ( The detection electrode 40 cannot be arranged in FIG. Therefore, it is difficult to increase the capacitances of the capacitors C1a, C1b, C2a, and C2b as compared with the present embodiment.

  Each embodiment disclosed this time must be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied particularly advantageously to a capacitive acceleration sensor.

It is a top view which shows roughly the structure of the acceleration sensor in Embodiment 1 of this invention. It is a schematic sectional drawing which follows the II-II line of FIG. It is sectional drawing which shows roughly a mode when the acceleration is applied to the acceleration sensor in Embodiment 1 of this invention upward along the film thickness direction of a board | substrate. It is a circuit diagram explaining the electrical connection of the capacitor | condenser formed by the 1st and 2nd detection frame of the acceleration sensor in Embodiment 1 of this invention, and a detection electrode. FIG. 3 is a cross-sectional view schematically showing a state in which negative angular acceleration around the X axis is applied to the center of gravity of the inertial mass body of the acceleration sensor according to Embodiment 1 of the present invention, and the cross-sectional position is the same as FIG. 2. FIG. 3 is a cross-sectional view schematically showing a state in which negative angular acceleration around the X axis is applied to the acceleration sensor in the first embodiment of the present invention at the center of gravity of the inertial mass body, and the cross-sectional position is the same as FIG. 2. is there. The state where the angular velocity which has the positive component of a Z-axis direction and the negative component of a Y-axis direction was added to the gravity center of the inertial mass body in Embodiment 1 of this invention is shown. FIG. 3 is a cross-sectional view schematically showing a state in which an angular velocity having a positive component in the Z-axis direction and a negative component in the Y-axis direction is applied to the acceleration sensor in the first embodiment of the present invention at the center of gravity of the inertial mass body. The cross-sectional position is the same as in FIG. It is a schematic sectional drawing which shows the 1st process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, The cross-sectional position respond | corresponds to the cross-sectional position of FIG. It is a schematic sectional drawing which shows the 2nd process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, The cross-sectional position respond | corresponds to the cross-sectional position of FIG. It is a schematic sectional drawing which shows the 3rd process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, The cross-sectional position respond | corresponds to the cross-sectional position of FIG. It is a schematic sectional drawing which shows the 4th process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, The cross-sectional position respond | corresponds to the cross-sectional position of FIG. It is a schematic sectional drawing which shows the 5th process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, The cross-sectional position respond | corresponds to the cross-sectional position of FIG. It is a top view which shows roughly the structure of the acceleration sensor in Embodiment 2 of this invention. It is sectional drawing which follows the XV-XV line | wire of FIG. It is a top view which shows roughly the structure of the acceleration sensor in Embodiment 3 of this invention. It is a top view which shows roughly the structure of the acceleration sensor in Embodiment 4 of this invention. It is a top view which shows roughly the structure of the acceleration sensor in Embodiment 5 of this invention. It is sectional drawing which shows schematically the structure of the acceleration sensor in Embodiment 6 of this invention. It is a circuit diagram explaining the electrical connection of the capacitor | condenser formed by the 1st and 2nd detection frame of the acceleration sensor in Embodiment 6 of this invention, and a detection electrode. It is a top view which shows roughly the structure of the acceleration sensor in Embodiment 7 of this invention. It is a fragmentary sectional view which shows roughly a mode when an acceleration is added to the upward direction along the film thickness direction of a board | substrate with respect to the acceleration sensor in Embodiment 7 of this invention. It is a graph which shows typically the relationship between the acceleration of the acceleration sensor in Embodiment 7 of this invention, and output potential. It is a top view which shows roughly the structure of the acceleration sensor in the comparative example of Embodiment 7 of this invention. It is a fragmentary sectional view which shows roughly a mode at the time of an acceleration being applied along the film thickness direction of a board | substrate with respect to the acceleration sensor in the comparative example of Embodiment 7 of this invention. It is a graph which shows typically the relationship between the acceleration of the acceleration sensor and output potential in the comparative example of Embodiment 7 of this invention. It is a top view which shows roughly the structure of the acceleration sensor in Embodiment 8 of this invention. It is a fragmentary sectional view which shows roughly a mode when the acceleration is applied upward along the film thickness direction of a board | substrate with respect to the acceleration sensor in Embodiment 8 of this invention. It is a top view which shows roughly the structure of the acceleration sensor in Embodiment 9 of this invention. It is a fragmentary sectional view which shows roughly a mode when the acceleration is applied upward along the film thickness direction of a board | substrate with respect to the acceleration sensor in Embodiment 9 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate, 2 Inertial mass body, 11 1st torsion beam, 12 2nd torsion beam, 21 1st detection frame, 22 2nd detection frame, 31 1st link beam, 32 2nd link beam, 40
Detection electrode, 41, 41a, 41b First detection electrode, 42, 42a, 42b Second detection electrode, 43, 43a, 43b Third detection electrode, 44, 44a, 44b Fourth detection electrode, 91, 92, 93, 94 anchor.

Claims (9)

A substrate,
A first torsion beam that twists about a first torsion axis supported by the substrate;
A first detection frame supported on the substrate via the first torsion beam so as to be rotatable about the first torsion axis;
A second torsion beam that twists about a second torsion axis supported by the substrate;
A second detection frame supported by the substrate via the second torsion beam so as to be rotatable about the second torsion axis;
A plurality of detection electrodes formed on the substrate so as to face each of the first and second detection frames, and detecting an angle of the first and second detection frames with respect to the substrate by capacitance;
A first link beam connected to the first detection frame on an axis moved in a direction intersecting the first torsion axis and in a direction toward one end of the first detection frame; ,
A second link beam connected to the second detection frame on an axis shifted in the direction opposite to the second twist axis;
An inertial mass body connected to each of the first and second detection frames by each of the first and second link beams and supported on the substrate so as to be displaceable in the thickness direction of the substrate. Acceleration sensor.   2. The acceleration sensor according to claim 1, wherein a dimension between the first torsion axis and the first link beam and a distance dimension between the second torsion axis and the second link beam are equal.   The acceleration sensor according to claim 1 or 2, wherein the first and second torsion axes are parallel to each other.   The acceleration sensor according to claim 1, further comprising a support beam for supporting the inertial mass body on the substrate so that the inertial mass body can be elastically displaced in a thickness direction of the substrate.   The acceleration sensor according to claim 1, further comprising a cap that covers the first and second detection frames.   The inertial mass body has a conductive portion, and further includes an electrode for electrostatically driving the inertial mass body in a thickness direction of the substrate on the substrate below the conductive portion. The acceleration sensor in any one of. The plurality of detection electrodes are:
A plurality of first detection electrodes formed on the substrate so as to face the first detection frame and detecting an angle of the first detection frame with respect to the substrate by a capacitance;
A plurality of second detection electrodes formed on the substrate so as to face the second detection frame and for detecting an angle of the second detection frame with respect to the substrate by a capacitance;
The plurality of first detection electrodes are provided symmetrically in plan view with respect to the rotation axis of the first detection frame, and the plurality of second detection electrodes are arranged with respect to the rotation axis of the second detection frame. The acceleration sensor according to claim 1, which is provided symmetrically in a plan view.   The acceleration sensor according to claim 7, wherein the center of gravity of each of the first and second detection frames is located on the axis of rotation of each of the first and second detection frames. The acceleration sensor according to claim 7, wherein each of the first torsion axis and the second torsion axis is a rotation axis of the first detection frame and a rotation axis of the second detection frame, respectively.

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