JP2011237393A - Movable body, two axis angular velocity sensor, and three axis acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of producing a compact sensor with high detection sensitivity.SOLUTION: The present invention is embodied as a movable body formed on a substrate. The movable body comprises a first frame body, a second frame body which is placed so as to be partly or completely superimposed on the first frame body with the first and second frame bodies opposing to each other, a coupling section which is linked with the first frame body via a first spring section and with the second frame body via a second spring section, and a stationary section which is linked with the coupling section via a third spring section and fixed to the substrate. Because in the first, second, and third spring sections, a spring constant in one direction is remarkably smaller than those in other directions, a relative displacement in the only one direction is substantially allowed. The directions in which the relative displacement is allowed by the first, second, and third spring sections are perpendicular to one another.

Description

  The present invention relates to a movable body formed on a substrate, a biaxial angular velocity sensor and a triaxial acceleration sensor including the movable body.

  Conventionally, a sensor that detects a physical quantity such as an angular velocity or an acceleration by forming a movable body including a mass body such as a frame mass on a semiconductor substrate and detecting a displacement amount of the mass body has been proposed. For example, when the X-axis and Y-axis are set in the direction along the substrate and the Z-axis is set in the direction orthogonal to the substrate, the acceleration in the X-axis direction is detected from the displacement amount of the mass body in the X-axis direction. An acceleration sensor that detects the acceleration in the Z-axis direction from the amount of displacement of the mass body in the Z-axis direction has been proposed. Alternatively, an angular velocity sensor is proposed that detects the angular velocity around the Y axis from the amount of displacement of the mass body in the Z-axis direction caused by Coriolis force by vibrating the mass body in the X-axis direction. Such a sensor is disclosed in Patent Documents 1-3.

  The single-axis angular velocity sensor (X-type gyroscope) of Patent Document 1 includes a first frame mass movable in the Z-axis direction, a second frame mass movable in the Y-axis direction, and the first frame mass in the Z-axis direction. Excitation means for oscillating the first frame mass, first detection means for detecting (monitoring) the displacement amount in the Z-axis direction of the first frame mass, and displacement of the second frame mass in the Y-axis direction Second detection means for detecting the amount is provided. Patent Document 1 describes that two such uniaxial angular velocity sensors are prepared, and one of them is rotated by 90 ° and arranged to be a biaxial angular velocity sensor. In the technique of Patent Document 1, the second frame mass is formed to be slightly smaller than the first frame mass, and the second frame mass is disposed inside the first frame mass, which is necessary for the biaxial angular velocity sensor. All the components are arranged in the same plane, and can be manufactured by a single mask.

JP 2003-194545 A JP 2005-55377 A JP 2006-271053 A

  In the technique of Patent Document 1, since the two frame masses are arranged in a double manner on the inside and outside in the same plane, the area inside the frame mass becomes small. Therefore, if the detection unit is arranged inside the frame mass, the area of the detection unit is reduced, and the physical quantity detection sensitivity is lowered. In order to increase the detection area in order to improve the detection sensitivity in the detection section, the inner frame mass and the outer frame mass must be formed larger, resulting in an increase in the occupied area of the entire apparatus. End up. It has been difficult to manufacture a sensor with high physical quantity detection sensitivity while the entire apparatus is small.

  The present invention has been created to solve the above-described problems, and provides a technique capable of manufacturing a sensor with high detection sensitivity while the entire apparatus is small.

  The present invention is embodied as a movable body formed on a substrate. The movable body includes a first frame, a second frame disposed so as to face each other and partially or completely overlap with the first frame, and a first spring portion. Connected to the first frame body, and connected to the second frame body via a second spring part, and connected to the joint part via a third spring part. And a fixing portion fixed to the substrate. The first spring part, the second spring part, and the third spring part have a significantly lower spring constant in one direction than the spring constant in the other direction, and allow a relative displacement in only one direction. To do. The directions in which the first spring portion, the second spring portion, and the third spring portion allow relative displacement are orthogonal to each other.

  In the movable body described above, the first frame body and the second frame body are arranged so as to face each other and partially or completely overlap each other. Compared to the case where the first frame body and the second frame body are arranged in the inner and outer doubles in the same plane, the area of the inner region can be secured widely. By using this movable body as a component of the sensor and arranging the detection unit for detecting the movement of the first frame or the second frame inside the first frame and the second frame, the area of the detection unit can be reduced. Widely secured. A sensor with high detection sensitivity can be realized while suppressing an increase in size of the entire apparatus.

  When the X and Y axes are set in a direction parallel to the substrate and the Z axis is set in a direction perpendicular to the substrate, the movable body is configured so that the first frame and the second frame are respectively X It is formed in a rectangular shape having sides along the axis and sides along the Y axis, the direction in which the first spring portion allows relative displacement is the Y axis direction, and the second spring portion exhibits relative displacement. The allowable direction is preferably the Z-axis direction, and the direction in which the third spring portion allows relative displacement is preferably the X-axis direction. Moreover, it is preferable that said movable body is further equipped with the Y direction detection part which detects the motion of the said 1st frame body in the Y-axis direction. Furthermore, it is preferable that the movable body includes a Z-direction detection unit that detects the movement of the second frame body in the Z-axis direction.

  The present invention can also be embodied as a biaxial angular velocity sensor including the above movable body. The biaxial angular velocity sensor of the present invention includes the movable body and an X-direction excitation unit that excites the coupling portion in the X-axis direction.

  According to this biaxial angular velocity sensor, the coupling portion, the first frame body, and the second frame body vibrate in the X-axis direction by exciting the coupling portion in the X-axis direction. When an angular velocity around the Y-axis acts on the biaxial angular velocity sensor, the second frame vibrates in the Z-axis direction by Coriolis force. By detecting the movement of the second frame body in the Z-axis direction by the Z-direction detection unit, the angular velocity around the Y-axis can be detected. Further, when an angular velocity around the Z-axis acts on this biaxial angular velocity sensor, the first frame body vibrates in the Y-axis direction by Coriolis force. By detecting the movement of the first frame body in the Y-axis direction by the Y-direction detection unit, the angular velocity around the Z-axis can be detected.

  The present invention can also be embodied as a three-axis acceleration sensor including the movable body. The triaxial acceleration sensor according to the present invention includes the movable body and an X-direction detection unit that detects the movement of the coupling portion in the X-axis direction.

  When acceleration in the X-axis direction acts on the three-axis acceleration sensor, the first frame, the second frame, and the coupling portion vibrate in the X-axis direction. By detecting the movement of the coupling portion in the X-axis direction by the X-direction detection unit, the acceleration in the X-axis direction can be detected. When acceleration in the Y-axis direction acts on this triaxial acceleration sensor, the first frame body vibrates in the Y-axis direction. The Y-axis direction acceleration can be detected by detecting the movement of the first frame in the Y-axis direction by the Y-direction detection unit. When acceleration in the Z-axis direction acts on this triaxial acceleration sensor, the second frame body vibrates in the Z-axis direction. By detecting the movement of the second frame in the Z-axis direction by the Z-direction detection unit, the acceleration in the Z-axis direction can be detected.

  According to the movable body, the biaxial angular velocity sensor, and the triaxial acceleration sensor of the present invention, a sensor with high detection sensitivity can be manufactured while the entire apparatus is small.

FIG. 3 is a plan view illustrating a configuration of a first Si layer 100 of the biaxial angular velocity sensor 10 according to the first embodiment. The top view which shows the structure of the 2nd Si layer 200 of the biaxial angular velocity sensor 10 of Example 1, and the triaxial acceleration sensor 20 of Example 2. FIG. The top view which shows the structure of the 3rd Si layer 300 of the biaxial angular velocity sensor 10 of Example 1, and the triaxial acceleration sensor 20 of Example 2. FIG. FIG. 3 is a longitudinal sectional view illustrating configurations of a biaxial angular velocity sensor 10 according to the first embodiment and a triaxial acceleration sensor 20 according to the second embodiment. FIG. 6 is a plan view illustrating a configuration of a first Si layer 500 of the triaxial acceleration sensor 20 according to the second embodiment.

The present invention can also be realized as a preferred embodiment by including the following features alone or in combination.
(Characteristic 1) The Z direction detection part is arrange | positioned inside the 1st frame and the 2nd frame.
(Feature 2) The first frame, the Y-direction detection unit, and the X-direction excitation unit are arranged in the same plane, and the Y-direction detection unit and the X-direction excitation unit are outside the first frame. Has been placed.
(Feature 3) The first frame, the Y direction detection unit, and the X direction detection unit are arranged in the same plane, and the Y direction detection unit and the X direction detection unit are located outside the first frame. Has been placed.

  FIG. 1 illustrates a configuration of a biaxial angular velocity sensor 10 including a movable body according to the first embodiment. The biaxial angular velocity sensor 10 is a biaxial angular velocity sensor that detects an angular velocity around the Y axis and an angular velocity around the Z axis.

  The biaxial angular velocity sensor 10 is formed between the first Si layer 100 shown in FIG. 1, the second Si layer 200 shown in FIG. 2, the third Si layer 300 shown in FIG. 3, and the first Si layer 100 and the second Si layer 200. The first oxide film 600 is formed, and an SOI (Silicon on Insulator) substrate having a structure in which a second oxide film 700 formed between the second Si layer 200 and the third Si layer 300 is laminated. For example, the first Si layer 100 is formed to be thicker than the second Si layer 200. Further, for example, the third Si layer 300 is formed to have a thickness larger than any of the first Si layer 100 and the second Si layer 200.

  As shown in FIG. 1, the first Si layer 100 includes a first frame mass 102, X-direction excitation units 104 a and 104 b that vibrate the first frame mass 102 in the X-axis direction, and the Y direction of the first frame mass 102. Y direction detectors 106a and 106b that detect the vibration of the first electrode, and fixed electrodes 108a and 108b and a movable electrode 110 that are part of a Z direction detector 240 described later are formed. The X-direction excitation units 104a and 104b are disposed outside the first frame mass 102 so as to sandwich the first frame mass 102 from both sides in the X-axis direction. The Y direction detection units 106a and 106b are arranged outside the first frame mass 102 so as to sandwich the first frame mass 102 from both sides in the Y axis direction. The fixed electrodes 108 a and 108 b and the movable electrode 110 are disposed inside the first frame mass 102.

  The X-direction excitation units 104 a and 104 b have a symmetrical configuration with the first frame mass 102 interposed therebetween. Hereinafter, a detailed configuration will be described by taking the X direction excitation unit 104a as an example, and detailed description of the X direction excitation unit 104b will be omitted. The X-direction excitation unit 104a includes a coupling unit 112a, an excitation electrode 114a, excitation unit springs 116a and 118a, fixing units 120a, 121a, 122a, and 123a, and first connection springs 124a and 126a. As shown in the figure, the excitation electrode 114a and the coupling portion 112a are alternately formed with comb-like electrodes on opposite sides. When the excitation electrode 114a is energized, the comb-shaped electrode of the coupling portion 112a is attracted to the gap between the comb-shaped electrodes of the excitation electrode 114a. Canceled. The coupling portion 112a is coupled to the first frame mass 102 via first coupling springs 124a and 126a extending along the X-axis direction. The first connecting springs 124a and 126a are configured such that the spring constant in the Y-axis direction is significantly smaller than the spring constants in the other directions, and only the relative displacement in the Y-axis direction is allowed. Y-axis direction spring. Therefore, the first frame mass 102 and the coupling portion 112a vibrate integrally in the X-axis direction and the Z-axis direction, and vibrate independently of each other in the Y-axis direction. One end of the coupling portion 112a in the Y-axis direction is connected to the fixing portions 120a and 121a via the excitation portion spring 116a. The other end of the coupling portion 112a in the Y-axis direction is connected to the fixing portions 122a and 123a via the excitation portion spring 118a. Exciter springs 116a and 118a are configured such that the spring constant in the X-axis direction is significantly smaller than the spring constant in the other direction, and is substantially configured to allow only relative displacement in the X-axis direction. X-axis direction spring. Accordingly, the relative displacement in the Y-axis direction and the Z-axis direction is constrained with respect to the fixing portions 120a, 121a, 122a, 123a, and the coupling portion 112a can be freely displaced in the X-axis direction. The excitation electrode 114a and the fixing parts 120a, 121a, 122a, 123a are fixed to the outer fixing part 230 of the second Si layer 200 described later via the first oxide film 600. The coupling portion 112a of the X direction excitation portion 104a, the excitation portion springs 116a and 118a, the fixing portions 120a, 121a, 122a, and 123a, and the first connection springs 124a and 126a are integrated with the first frame mass 102. These members are electrically connected.

  The Y direction detection units 106 a and 106 b have a vertically symmetric configuration with the first frame mass 102 interposed therebetween. Hereinafter, a detailed configuration will be described by taking the Y direction detection unit 106a as an example, and detailed description of the Y direction detection unit 106b will be omitted. The Y direction detection unit 106a includes a detection frame 130a, detection unit springs 132a, 134a, 136a, and 138a, fixed units 140a, 142a, 144a, and 146a, fixed electrodes 148a and 150a, and movable electrodes 152a and 154a. Detection electrodes 156a and 158a, and second connecting springs 160a and 162a. The detection unit springs 132a, 134a, 136a, 138a, the fixed units 140a, 142a, 144a, 146a, the fixed electrodes 148a, 150a, the movable electrodes 152a, 154a, and the detection electrodes 156a, 158a are included in the detection frame 130a. Arranged inside. Both ends in the X-axis direction of the detection frame 130a are connected to the first frame mass 102 via second connection springs 160a and 162a, respectively. The second connecting springs 160a and 162a are configured such that the spring constant in the X-axis direction is significantly smaller than the spring constant in the other direction, and is configured to substantially allow only relative displacement in the X-axis direction. X-axis direction spring. Accordingly, the first frame mass 102 and the detection frame 130a vibrate integrally in the Y-axis direction and the Z-axis direction, and vibrate independently of each other in the X-axis direction. One end of each of the detection unit springs 132a, 134a, 136a, 138a is connected to the vicinity of the four corners of the detection frame 130a, and the other end is connected to each of the fixing units 140a, 142a, 144a, 146a. The detector springs 132a, 134a, 136a, and 138a are configured such that the spring constant in the Y-axis direction is significantly smaller than the spring constants in the other directions, so that substantially only relative displacement in the Y-axis direction is allowed. It is the Y-axis direction spring comprised in this. Accordingly, the relative displacement in the X-axis direction and the Z-axis direction is restricted with respect to the fixing portions 140a, 142a, 144a, and 146a, and the detection frame 130a can be freely displaced in the Y-axis direction. The movable electrodes 152a and 154a are arranged so as to extend from the detection frame 130a along the X-axis direction. The fixed electrodes 148a and 150a are arranged so as to extend from the detection electrodes 156a and 158a along the X-axis direction. The movable electrode 152a is disposed so as to sandwich the fixed electrode 148a from both sides, and the movable electrode 152a and the fixed electrode 148a constitute a capacitance. The movable electrode 154a is arranged so as to sandwich the fixed electrode 150a from both sides, and the movable electrode 154a and the fixed electrode 150a constitute a capacitance. When the detection frame 130a vibrates in the Y-axis direction with respect to the detection electrodes 156a and 158a, the capacitance formed by the fixed electrodes 148a and 150a and the movable electrodes 152a and 154a changes. This change in capacitance can be detected as a signal using a CV conversion circuit (not shown). The detection electrodes 156a and 158a and the fixing parts 140a, 142a, 144a and 146a are fixed to the outer fixing part 230 of the second Si layer 200 described later via the first oxide film 600. The Y direction detection unit 106a includes a detection frame 130a, detection unit springs 132a, 134a, 136a, and 138a, fixed units 140a, 142a, 144a, and 146a, movable electrodes 152a and 154a, and a second connection. The springs 160a and 162a are formed integrally with the first frame mass 102, and these members are electrically connected.

  The first frame mass 102 is a mass body having a rectangular frame shape (frame shape). The first frame mass 102 is vibrated in the X direction by the X direction excitation units 104a and 104b. Specifically, when the excitation electrode 114a of the X-direction excitation unit 104a is energized and the energization of the excitation electrode 114b of the X-direction excitation unit 104b is released, the coupling unit 112a moves toward the left side of FIG. The first frame mass 102 also moves toward the left side of FIG. When the energization of the excitation electrode 114b of the X-direction excitation unit 104b is released and the excitation electrode 114b of the X-direction excitation unit 104b is energized, the coupling unit 112b moves toward the right side of FIG. Move toward the right side of FIG. As described above, the first frame mass 102 vibrates in the X-axis direction by energizing the excitation electrodes 114a and 114b of the X-direction excitation units 104a and 104b alternately.

  In a situation where the first frame mass 102 vibrates in the X-axis direction, when an angular velocity around the Z-axis acts on the first frame mass 102, a Coriolis force in the Y-axis direction acts on the first frame mass 102, and One frame mass 102 vibrates also in the Y-axis direction. The vibration in the Y-axis direction of the first frame mass 102 is also transmitted to the detection frames 130a and 130b of the Y-direction detection units 106a and 106b, and is detected as a change in signal output at the detection electrodes 156a and 158a.

  In a situation where the first frame mass 102 is vibrating in the X-axis direction, when an angular velocity around the Y-axis acts on the first frame mass 102, a Coriolis force in the Z-axis direction acts on the first frame mass 102. . However, the excitation part springs 116a, 118a, 116b, 118b, the first connection springs 124a, 126a, 124b, 126b, the second connection springs 160a, 162a, 160b, 162b and the detection part springs 132a, 134a, 136a, 138a, 132b, 134b, 136b, and 138b have high rigidity in the Z-axis direction, that is, a large spring constant in the Z-axis direction. For this reason, the first frame mass 102 is fixed to the fixing portions 120a, 121a, 122a, 123a, 120b, 121b, 122b, 123b of the X direction excitation units 104a, 104b and the fixing portions 140a, 142a, 144a of the Y direction detection units 106a, 106b. 146a, 140b, 142b, 144b, and 146b are restrained from displacement in the Z-axis direction. Accordingly, the first frame mass 102 hardly vibrates in the Z-axis direction.

  As shown in FIG. 2, the second frame layer 202, the third connection springs 204a, 204b, 206a, 206b, the movable electrodes 208a, 208b, the fixed electrode 209, and the detection unit are connected to the second Si layer 200. Springs 210a, 210b, 212a, 212b, detection portion supporting springs 214a, 214b, 216a, 216b, fixing portions 218, 220, 222a, 222b, 224a, 224b, 226a, 226b, and an outer fixing portion 230. ing. The outer fixing portion 230 is fixed to a third Si layer 300 described later via a second oxide film 700. Hereinafter, the movable electrodes 208a and 208b, the fixed electrode 209, the detection unit coupling springs 210a, 210b, 212a and 212b, the detection unit support springs 214a, 214b, 216a and 216b, and the fixed units 218, 220 and 222a. , 222b, 224a, 224b, 226a, 226b, the fixed electrodes 108a, 108b of FIG. 1, and the movable electrode 110 are collectively referred to as a Z direction detector 240.

  The third connecting springs 204a and 206a extend from one end portion (left end portion in FIG. 2) of the second frame mass 202 in the X-axis direction along the X-axis direction. The end portions of the third coupling springs 204a and 206a are connected to the coupling portion 112a of the X direction excitation portion 104a of FIG. 1 via the first oxide film 600. The third connecting springs 204b and 206b extend along the X-axis direction from the other end portion (right end portion in FIG. 2) of the second frame mass 202 in the X-axis direction. The end portions of the third coupling springs 204b and 206b are connected to the coupling portion 112b of the X-direction excitation portion 104b of FIG. 1 via the first oxide film 600. The third connecting springs 204a, 204b, 206a, 206b are configured so that the spring constant in the Z-axis direction is significantly smaller than the spring constants in the other directions, and substantially only relative displacement in the Z-axis direction is allowed. It is a Z-axis direction spring configured to do this. Accordingly, the coupling portion 112a of the second frame mass 202 and the X-direction excitation portion 104a and the coupling portion 112b of the second frame mass 202 and the X-direction excitation portion 104b vibrate integrally in the X-axis direction and the Y-axis direction. Oscillate independently of each other in the Z-axis direction.

  Furthermore, the end portions of the third coupling springs 204a and 206a are electrically connected to the coupling portion 112a of the X-direction excitation portion 104a via the through electrodes 232a and 234a, respectively. The end portions of the third coupling springs 204b and 206b are electrically connected to the coupling portion 112b of the X direction excitation portion 104b via the through electrodes 232b and 234b, respectively. Since the coupling portions 112a and 112b of the X-direction excitation units 104a and 104b are electrically connected to the first frame mass 102, the first frame mass 102 and the second frame mass 202 are maintained at the same potential.

  The movable electrodes 208 a and 208 b are formed inside the second frame mass 202. The movable electrode 208a is connected to the second frame mass 202 via the detection unit coupling springs 210a and 212a. The movable electrode 208b is connected to the second frame mass 202 via the detection unit coupling springs 210b and 212b. The detection unit coupling springs 210a, 210b, 212a, and 212b are configured so that the spring constant in the X-axis direction is significantly smaller than the spring constants in the other directions, and substantially only relative displacement in the X-axis direction is allowed. An X-axis direction spring configured to Accordingly, the movable electrodes 208a and 208b vibrate integrally with respect to the second frame mass 202 in the Y-axis direction and the Z-axis direction, and vibrate independently of each other in the X-axis direction.

  The movable electrode 208a is connected to the fixed portions 222a and 224a via the detection portion supporting springs 214a and 216a. The movable electrode 208b is connected to the fixed portions 222b and 224b via the detection portion supporting springs 214b and 216b. The detection unit supporting springs 214a, 214b, 216a, and 216b are configured such that the spring constant in the Z-axis direction is significantly smaller than the spring constants in the other directions, and substantially only relative displacement in the Z-axis direction is allowed. It is a Z-axis direction spring configured to do this. Therefore, the movable electrode 208a is restrained from relative displacement in the X-axis direction and the Y-axis direction with respect to the fixed portions 222a and 224a, and can be freely displaced in the Z-axis direction. Further, the movable electrode 208b is restrained from relative displacement in the X-axis direction and the Y-axis direction with respect to the fixed portions 222b and 224b, and can be freely displaced in the Z-axis direction. The fixing portions 222a and 224a are fixed to the convex portion 306a of the third Si layer 300 described later via the second oxide film 700. The fixing portions 222b and 224b are fixed to the convex portion 306b of the third Si layer 300 described later via the second oxide film 700. The movable electrodes 208a, 208b, the detection unit coupling springs 210a, 210b, 212a, 212b, the detection unit support springs 214a, 214b, 216a, 216b, and the fixed units 222a, 222b, 224a, 224b are included in the second frame mass 202. And these members are electrically connected. The movable electrodes 208a and 208b are both mechanically connected to the movable electrode 110 of FIG. 1 through the first oxide film 600, and are electrically connected to each other through the through electrodes 236a and 236b. . Note that the portion where the fixed electrode 108a in FIG. 1 overlaps when viewed in plan on the XY plane of the movable electrode 208a and the portion where the fixed electrode 108b in FIG. 1 overlaps when viewed in plan on the XY plane of the movable electrode 208b are etched, respectively. Holes are formed. The first oxide film 600 between the movable electrode 208a and the fixed electrode 108a is removed by etching, and both are separated mechanically and electrically. In addition, the first oxide film 600 between the movable electrode 208b and the fixed electrode 108b is also removed by etching, and both are separated mechanically and electrically.

The fixed portion 226a is mechanically connected to the fixed electrode 108a of FIG. 1 through the first oxide film 600. The fixing portion 226a is mechanically connected to a convex portion 304a of the third Si layer 300 described later via the second oxide film 700. Further, the fixed portion 226a is electrically connected to the fixed electrode 108a via the through electrode 238a.
Similarly, the fixed portion 226b is mechanically connected to the fixed electrode 108b of FIG. 1 through the first oxide film 600. Further, the fixing portion 226b is mechanically connected to the convex portion 304b of the third Si layer 300 described later via the second oxide film 700. Further, the fixed portion 226b is electrically connected to the fixed electrode 108b via the through electrode 238b.

  Both ends of the fixed electrode 209 in the X-axis direction are connected to the fixed portions 218 and 220, respectively. The fixing portions 218 and 220 are mechanically connected to convex portions 306a and 306b of the third Si layer 300 described later via the second oxide film 700, respectively. Note that an etching hole is formed in a portion overlapping the movable electrode 110 in FIG. 1 when viewed in plan on the XY plane of the fixed electrode 209. The first oxide film 600 between the fixed electrode 209 and the movable electrode 110 is removed by etching, and both are separated mechanically and electrically.

  As shown in FIG. 4, the movable electrode 110 of the first Si layer 100 and the fixed electrode 209 of the second Si layer 200 are arranged opposite to each other in the Z-axis direction, and an electrostatic capacity corresponding to the distance d1 between them is formed. Has been. Further, the fixed electrode 108a of the first Si layer 100 and the movable electrode 208a of the second Si layer 200 are arranged to face each other, and an electrostatic capacity corresponding to the distance d2 between them is formed. Similarly, the fixed electrode 108b of the first Si layer 100 and the movable electrode 208b of the second Si layer 200 are arranged to face each other, and an electrostatic capacity corresponding to the distance d2 between them is formed. When the second frame mass 202 is displaced in the Z direction, the movable electrodes 208 a, 208 b, 110 are displaced in the Z direction integrally with the second frame mass 202. As shown in FIG. 4, when the second frame mass 202 is displaced in the direction away from the first frame mass 102 (downward in FIG. 4), the distance d1 between the movable electrode 110 and the fixed electrode 209 decreases and is fixed. The distance d2 between the electrodes 108a and 108b and the movable electrodes 208a and 208b increases. Conversely, when the second frame mass 202 is displaced in a direction approaching the first frame mass 102 (upward in FIG. 4), the distance d1 between the movable electrode 110 and the fixed electrode 209 increases, and the fixed electrodes 108a and 108b. And the distance d2 between the movable electrodes 208a and 208b decreases. That is, a differential capacitance is formed in the Z direction detection unit 240. When the second frame mass 202 vibrates in the Z-axis direction, the above-described capacitance changes. This change in capacitance can be detected as a signal using a CV conversion circuit (not shown).

  The second frame mass 202 is a mass body having the same shape as the first frame mass 102 and having a rectangular frame shape (frame shape). The second frame mass 202 is disposed so as to completely overlap the first frame mass 102 when viewed in plan on the XY plane. When the coupling portions 112a and 112b are vibrated in the X direction by the X direction excitation portions 104a and 104b in FIG. 1, the second frame mass 202 also vibrates in the X axis direction.

  In a situation where the second frame mass 202 is vibrating in the X-axis direction, if an angular velocity around the Y-axis acts on the second frame mass 202, a Coriolis force in the Z-axis direction acts on the second frame mass 202, and The two-frame mass 202 vibrates also in the Z-axis direction. The vibration in the Z-axis direction of the second frame mass 202 is also transmitted to the movable electrodes 208a, 208b, 110 of the Z-direction detector 240, and is detected as a change in signal output at the fixed electrodes 108a, 108b, 209.

  In a situation where the second frame mass 202 is vibrating in the X-axis direction, when an angular velocity around the Z-axis acts on the second frame mass 202, a Coriolis force in the Y-axis direction acts on the second frame mass 202. . However, the excitation unit springs 116a, 118a, 116b, 118b, the detection unit support springs 214a, 214b, 216a, 216b, the third connection springs 204a, 204b, 206a, 206b, and the detection unit connection springs 210a, 210b, 212a. 212b have high rigidity in the Y-axis direction, that is, a large spring constant in the Y-axis direction. For this reason, the second frame mass 202 is fixed to the fixing portions 120a, 121a, 122a, 123a, 120b, 121b, 122b, 123b of the X direction excitation portions 104a, 104b of FIG. 1 and the fixing portions 222a, 224a, 222b, 224b of FIG. In contrast, the displacement in the Y-axis direction is constrained. Accordingly, the second frame mass 202 hardly vibrates in the Y-axis direction.

  As shown in FIG. 3, the third Si layer 300 includes a recess 302 formed by etching, and convex portions 304 a, 304 b, 306 a, and 306 b formed inside the recess 302. The convex portion 304 a is formed corresponding to the fixed portion 226 a of the second Si layer 200, and the convex portion 304 b is formed corresponding to the fixed portion 226 b of the second Si layer 200. The convex portion 306a is formed corresponding to the fixing portions 218, 222a, and 222b of the second Si layer 200, and the convex portion 306b is formed corresponding to the fixing portions 220, 224a, and 224b of the second Si layer 200. As shown in FIG. 4, since the recess 302 is formed corresponding to the second frame mass 202 and the movable electrodes 208a and 208b that vibrate in the Z-axis direction, the second frame mass 202 is connected to the movable electrodes 208a and 208b. Even when vibrating in the Z-axis direction integrally, the members of the third Si layer 300 do not interfere with each other.

  The biaxial angular velocity sensor 10 having the above configuration operates as follows. When the coupling portions 112a and 112b are excited in the X direction by the X direction excitation portions 104a and 104b, the vibration is transmitted to the first frame mass 102 via the first connection springs 124a, 124b, 126a and 126b, and One frame mass 102 vibrates in the X direction. When the angular velocity around the Z-axis acts on the first frame mass 102 in a state where the first frame mass 102 vibrates in the X direction, Coriolis force along the Y-axis direction acts on the first frame mass 102, and the first The frame mass 102 also vibrates in the Y direction. The vibration in the Y-axis direction of the first frame mass 102 is transmitted to the detection frames 130a and 130b of the Y-direction detection units 106a and 106b via the second connecting springs 160a, 162a, 160b, and 162b, and is detected by the detection electrodes. It is detected as a change in signal output at 156a, 158a, 156b, 158b.

  The vibration in the X direction of the coupling portions 112a and 112b is also transmitted to the second frame mass 202 via the third coupling springs 204a, 204b, 206a, and 206b, and the second frame mass 202 also vibrates in the X direction. . When the angular velocity around the Y axis acts on the second frame mass 202 while the second frame mass 202 is vibrating in the X direction, Coriolis force along the Z axis direction acts on the second frame mass 202, and the second The frame mass 202 also vibrates in the Z direction. The vibration in the Z-axis direction of the second frame mass 202 is also transmitted to the movable electrodes 208a, 208b, 110 via the detection connecting springs 210a, 212a, 210b, 212b, and a signal output at the fixed electrodes 108a, 108b, 209. Is detected as a change.

  Etching holes are formed in the first frame mass 102 of the first Si layer 100 and the second frame mass 202 of the second Si layer 200, respectively. By forming these etching holes, the first oxide film 600 between the first Si layer 100 and the second Si layer 200 and the second oxide film 700 between the second Si layer 200 and the third Si layer 300 are formed. Can be appropriately removed.

  As described above, according to the biaxial angular velocity sensor 10 of the present embodiment, the angular velocity around the Y axis and the angular velocity around the Z axis can be detected.

  In the biaxial angular velocity sensor 10 of the present embodiment, the first frame mass 102 and the second frame mass 202 are not arranged on the same plane, but are arranged so as to face each other and overlap each other. Accordingly, a wide area inside the first frame mass 102 and the second frame mass 202 can be secured. By adopting such a configuration, the area where the fixed electrode 209 and the movable electrode 110 of the Z direction detection unit 240 face each other, the area where the movable electrode 208a and the fixed electrode 108a face each other, and the movable electrode 208b and the fixed electrode 108b face each other. A large area can be secured, and the detection sensitivity of the Z direction detection unit 240 can be improved. In addition, as compared with the case where the first frame mass 102 and the second frame mass 202 are arranged on the same plane, for example, the first frame mass 102 is arranged on the outer side and the second frame mass 202 is arranged on the inner side, The area can be reduced. The biaxial angular velocity sensor 10 can be further downsized.

  In the biaxial angular velocity sensor 10 of the present embodiment, the first coupling springs 124a, 124b, 126a, 126b and the second coupling springs 160a, 160b, 162a, 162b connected to the first frame mass 102 are interposed via an oxide film. 3rd connection springs 204a, 204b, 206a, 206b, detection unit connection springs 210a, 210b, 212a, 212b, etc., which are integrally formed with the first frame mass 102 and connected to the second frame mass 202, etc. However, the second frame mass 202 is formed integrally with no oxide film. With such a configuration, it is possible to prevent a situation in which the residual stress of the oxide film causes the first frame mass 102 and the second frame mass 202 to warp. The center-of-gravity shift of the first frame mass 102 and the second frame mass 202 due to the occurrence of warpage can be prevented. Further, as described above, by connecting the frame masses and the springs without interposing an oxide film, it is possible to prevent the occurrence of problems during manufacturing, such as careless overetching of the oxide film.

  In the above-described embodiment, the case where the first frame mass 102 and the second frame mass 202 completely overlap when viewed in plan on the XY plane has been described. However, the first frame mass 102 and the second frame mass 202 are partially It is good also as a structure which overlaps. The fixed electrodes 108 a and 108 b and the movable electrode 110 of the first Si layer 100 can be formed inside the first frame mass 102, and the fixed electrodes 108 a and 108 b and the movable electrode 110 are part of the Z direction detection unit 240. The first frame mass 102 and the second frame mass 202 do not have to completely overlap when viewed in plan on the XY plane.

  The biaxial angular velocity sensor 10 according to the first embodiment can be a triaxial acceleration sensor by making a partial change. In the present embodiment, with respect to the triaxial acceleration sensor 20 having a movable body, portions having the same configuration as the biaxial angular velocity sensor 10 of the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only portions to be changed are provided. Will be described.

  The triaxial acceleration sensor 20 is formed between the first Si layer 500 shown in FIG. 5, the second Si layer 200 shown in FIG. 2, the third Si layer 300 shown in FIG. 3, and the first Si layer 500 and the second Si layer 200. The first oxide film 600 is formed, and an SOI (Silicon on Insulator) substrate having a structure in which a second oxide film 700 formed between the second Si layer 200 and the third Si layer 300 is laminated. The configurations of the second Si layer 200 and the third Si layer 300 are the same as those in the first embodiment. For example, the first Si layer 500 is formed to be thicker than the second Si layer 200. Further, for example, the third Si layer 300 is formed to have a thickness larger than any of the first Si layer 500 and the second Si layer 200.

  As illustrated in FIG. 5, the first Si layer 500 includes a first frame mass 102, X-direction detection units 506 a and 506 b that detect vibrations in the X direction of the first frame mass 102, and Y of the first frame mass 102. Y direction detectors 106a and 106b that detect vibrations in the direction, fixed electrodes 108a and 108b and a movable electrode 110 that are part of the Z direction detector 240 are formed. The X direction detection units 506a and 506b are arranged outside the first frame mass 102 so as to sandwich the first frame mass 102 from both sides in the X axis direction.

  The X direction detection units 506a and 506b have a symmetrical configuration with the first frame mass 102 interposed therebetween. Hereinafter, the detailed configuration will be described by taking the X direction detection unit 506a as an example, and the detailed description of the X direction detection unit 506b will be omitted. The X direction detection unit 506a includes a detection frame 530a, detection unit springs 532a, 534a, 536a, 538a, fixed units 540a, 542a, 544a, 546a, fixed electrodes 548a, 550a, movable electrodes 552a, 554a, , Detection electrodes 556a and 558a, and fourth connecting springs 560a and 562a. The detection unit springs 532a, 534a, 536a, and 538a, the fixed units 540a, 542a, 544a, and 546a, the fixed electrodes 548a and 550a, the movable electrodes 552a and 554a, and the detection electrodes 556a and 558a are included in the detection frame 530a. Arranged inside. Both ends in the Y-axis direction of the detection frame 530a are connected to the coupling portion 112a via fourth coupling springs 560a and 562a, respectively. The fourth connecting springs 560a and 562a are configured such that the spring constant in the Y-axis direction is significantly smaller than the spring constants in the other directions, and only the relative displacement in the Y-axis direction is allowed. Y-axis direction spring. Accordingly, the first frame mass 102, the coupling portion 112a, and the detection frame 530a vibrate integrally in the X axis direction and the Z axis direction, and vibrate independently of each other in the Y axis direction. One end of each of the detection unit springs 532a, 534a, 536a, and 538a is connected to the vicinity of the four corners of the detection frame 530a, and the other end is connected to each of the fixing units 540a, 542a, 544a, and 546a. The detection unit springs 532a, 534a, 536a, and 538a are configured such that the spring constant in the X-axis direction is significantly smaller than the spring constants in the other directions so that only relative displacement in the X-axis direction is allowed. It is the X-axis direction spring comprised in this. Therefore, the relative displacement in the Y-axis direction and the Z-axis direction is restricted with respect to the fixing portions 540a, 542a, 544a, and 546a, and the detection frame 530a can be freely displaced in the X-axis direction. The movable electrodes 552a and 554a are arranged so as to extend from the detection frame 530a along the Y-axis direction. The fixed electrodes 548a and 550a are arranged so as to extend from the detection electrodes 556a and 558a along the Y-axis direction. The movable electrode 552a is disposed so as to sandwich the fixed electrode 548a from both sides, and the movable electrode 552a and the fixed electrode 548a constitute a capacitance. The movable electrode 554a is disposed so as to sandwich the fixed electrode 550a from both sides, and the movable electrode 554a and the fixed electrode 550a constitute an electrostatic capacity. When the detection frame 530a vibrates in the X-axis direction with respect to the detection electrodes 556a and 558a, the capacitance formed by the fixed electrodes 548a and 550a and the movable electrodes 552a and 554a changes. This change in capacitance can be detected as a signal using a CV conversion circuit (not shown). The detection electrodes 556a and 558a and the fixing portions 540a, 542a, 544a and 546a are fixed to the outer fixing portion 230 of the second Si layer 200 via the first oxide film 600. Note that the detection frame 530a, the detection unit springs 532a, 534a, 536a, and 538a, the fixed units 540a, 542a, 544a, and 546a, the movable electrodes 552a and 554a, and the fourth connection for the X direction detection unit 506a. The springs 560a and 562a are formed integrally with the coupling portion 112a and the first frame mass 102, and these members are electrically connected.

  The triaxial acceleration sensor 20 having the above configuration operates as follows. When acceleration in the X-axis direction acts on the triaxial acceleration sensor 20, the first frame mass 102, the second frame mass 202, and the coupling portions 112a and 112b integrally vibrate in the X-axis direction. The vibration is transmitted to the detection frames 530a and 530b of the X-direction detection units 506a and 506b via the fourth connection springs 560a and 562a, and is detected as a change in signal output at the detection electrodes 556a, 558a, 556b, and 558b. The

  When acceleration in the Y-axis direction acts on the triaxial acceleration sensor 20, the first frame mass 102 vibrates in the Y direction. The vibration in the Y-axis direction of the first frame mass 102 is transmitted to the detection frames 130a and 130b of the Y-direction detection units 106a and 106b via the second connecting springs 160a, 162a, 160b, and 162b, and is detected by the detection electrodes. It is detected as a change in signal output at 156a, 158a, 156b, 158b.

  When acceleration in the Z-axis direction acts on the triaxial acceleration sensor 20, the second frame mass 202 vibrates in the Z direction. The vibration in the Z-axis direction of the second frame mass 202 is also transmitted to the movable electrodes 208a, 208b, 110 via the detection connecting springs 210a, 212a, 210b, 212b, and a signal output at the fixed electrodes 108a, 108b, 209. Is detected as a change.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. In addition, the technical elements described in the present specification or drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in the present specification or the drawings can achieve a plurality of objects at the same time, and has technical utility by achieving one of the objects.

10 2-axis angular velocity sensor 20 3-axis acceleration sensor 100 1st Si layer 102 1st frame mass 104a, 104b X direction excitation unit 106a, 106b Y direction detection unit 108a, 108b Fixed electrode 110 Movable electrode 112a, 112b Coupling unit 114a, 114b Excitation Electrodes 116a, 118a, 116b, 118b Excitation springs 120a, 121a, 122a, 123a, 120b, 121b, 122b, 123b Fixing parts 124a, 126a, 124b, 126b First connection springs 130a, 130b Detection frames 132a, 134a 136a, 138a, 132b, 134b, 136b, 138b Detector springs 140a, 142a, 144a, 146a, 140b, 142b, 144b, 146b Fixed portions 148a, 150a, 148b, 150b Fixed electrode 1 2a, 154a, 152b, 154b Movable electrodes 156a, 158a, 156b, 158b Detection electrodes 160a, 162a, 160b, 162b Second connection spring 200 Second Si layer 202 Second frame mass 204a, 204b, 206a, 206b For third connection Spring 208a, 208b Movable electrode 209 Fixed electrode 210a, 210b, 212a, 212b Detection unit coupling spring 214a, 214b, 216a, 216b Detection unit support spring fixing unit 218, 220, 222a, 222b, 224a, 224b, 226a, 226b
230 Outer fixed part 232a, 234a, 236a, 238a, 232b, 234b, 236b, 238b Through electrode 240 Z direction detection part 300 Third Si layer 304a, 306a, 304b, 306b Convex part 500 First Si layer 506a, 506b X direction detection part 530a, 530b Detection frames 532a, 534a, 536a, 538a, 532b, 534b, 536b, 538b Detector springs 540a, 542a, 544a, 546a, 540b, 542b, 544b, 546b Fixing portions 548a, 550a, 548b, 550b Electrodes 552a, 554a, 552b, 554b Movable electrodes 556a, 558a, 556b, 558b Detection electrodes 560a, 562a, 560b, 562b Fourth connection spring 600 First oxide film 700 Second oxide film

Claims (6)

A movable body formed on a substrate,
A first frame,
A second frame disposed opposite to each other and partially or completely overlapping the first frame;
A coupling portion connected to the first frame body via a first spring portion and connected to the second frame body via a second spring portion;
A fixed portion fixed to the substrate, connected to the coupling portion via a third spring portion;
The first spring part, the second spring part, and the third spring part have a significantly lower spring constant in one direction than the spring constant in the other direction, and allow a relative displacement in only one direction. And
A movable body in which directions in which the first spring portion, the second spring portion, and the third spring portion allow relative displacement are orthogonal to each other. When the X axis and the Y axis are set in a direction parallel to the substrate, and the Z axis is set in a direction perpendicular to the substrate,
The first frame and the second frame are each formed in a rectangular shape having sides along the X axis and sides along the Y axis,
The direction in which the first spring portion allows relative displacement is the Y-axis direction,
The direction in which the second spring portion allows relative displacement is the Z-axis direction,
The movable body according to claim 1, wherein a direction in which the third spring portion allows relative displacement is an X-axis direction.   The movable body according to claim 2, further comprising a Y-direction detection unit that detects movement in the Y-axis direction of the first frame body.   The movable body according to claim 3, further comprising a Z-direction detection unit that detects movement in the Z-axis direction of the second frame body. A movable body according to claim 4,
A biaxial angular velocity sensor including an X-direction excitation unit that excites the coupling unit in the X-axis direction. A movable body according to claim 4,
A three-axis acceleration sensor comprising an X-direction detection unit that detects movement in the X-axis direction of the coupling unit.

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