JP2012078121A - Physical quantity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To especially provide a thin physical quantity sensor capable of spreading a detection range in the height direction (Z axis direction) to further obtain stable sensor sensitivity.SOLUTION: A physical quantity sensor has: an anchor part which is fixed to be supported; a movable part 2 which is displaced in the height direction; support parts 3, 4 rotatably connected via a connection part to be elastically deformed; and a detection part 36 for detecting displacement of the movable part 2. The support parts are provided with leg parts 3b, 4b which are displaced in the opposite direction to the displacement direction of the movable part 2 when the movable part 2 is displaced in the height direction. The leg parts 3b, 4b are formed to be elastically displaced so that the leg parts 3b, 4b bend from a state of contacting the surface 30a of a facing part 30 which the legs 3b, 4b face in the height direction and the movable part 2 is displaced in the direction further being separated from the surface of the facing part.

Description

  The present invention relates to a physical quantity sensor that detects a displacement amount of a movable part formed by cutting out from a silicon substrate, and thereby enables measurement of a physical quantity such as acceleration acting from the outside.

  For example, the physical quantity sensor includes a movable portion that is supported so as to be displaceable in the height direction by etching a silicon substrate. In such a case, as described in Patent Document 1 below, the movable portion that is displaced in the height direction has a structure that is swingably supported via a beam portion that can be deformed by a frame located around the movable portion. is there. However, if a strong physical quantity acts on the movable part, or if the physical quantity acts for a long time, the load on the beam part will be large, the beam part will be damaged, etc., and even if the physical quantity disappears, it will be restored to its original stationary state The sensor sensitivity is likely to be lowered due to the inability to do so, and the sensor life could not be extended effectively.

  On the other hand, the invention described in Patent Document 3 discloses an acceleration sensor capable of expanding the dynamic range.

  However, in the invention described in Patent Document 3, the movable part (weight part) is supported so as to be displaceable in the horizontal direction of the X axis and the Y axis, and the movable part is displaced in the Z axis direction (height direction). For example, the acceleration sensor shown in FIG. 1 of Patent Document 3 must be held 90 degrees. Therefore, with the configuration of Patent Document 3, a thin Z-axis acceleration sensor cannot be obtained.

  Further, in the invention described in Patent Document 3, when a very large acceleration is applied, the movable part (weight part) may collide with the stopper surface, which causes damage to the movable part having a large mass. There is a possibility of receiving. Therefore, there is a problem that the sensor sensitivity tends to become unstable.

  Further, in the invention described in Patent Document 3, when the movable part (weight part) is displaced by receiving acceleration, the protrusion 32 shown in FIG. 1 of Patent Document 3 collides with the stopper 30. At this time, it is necessary to form the protrusion with high rigidity so that the protrusion does not bend. When a larger acceleration is applied, in order to further displace the movable part, it is necessary to bend the stopper in contact with the protrusion, but the movable part with the protrusion only by one elongated stopper. Since the stopper is exhausted, the sensor sensitivity is likely to become unstable, for example, the stopper is exhausted and is not properly restored to the original state.

  The invention described in Patent Document 4 also discloses a semiconductor piezo sensor for obtaining a wide dynamic range.

  However, in the invention described in Patent Document 4, since the plurality of movable parts (the first protrusion stopper part and the second protrusion stopper part) are in direct contact with the opposing surface, the movable part is easily damaged, and the sensor There was a problem that sensitivity was likely to be unstable.

  Further, referring to FIG. 3 and FIG. 4 of Patent Document 4, firstly, after the first strained portion of reference numeral 22 is deformed and the first protrusion stopper portion of reference numeral 23 comes into contact with the opposing surface, the reference numeral 24 of FIG. 2 The deformation portion is deformed, and the second protrusion stopper portion 27 is in contact with the opposing surface lowered by one step.

  However, in the configuration of Patent Document 4, when a very large acceleration is applied, the first strain-generating portion and the second strain-generating portion may be simultaneously deformed. It is considered that the timing at which the portion comes into contact with the facing surface lowered one step is not so different from the timing at which the first protrusion stopper portion comes into contact with the facing surface, and the dynamic range cannot be stably expanded.

JP 2005-283393 A Pamphlet of International Publication No. 2005/099125 JP-A-5-340955 Japanese Patent Laid-Open No. 3-112168 Pamphlet of International Publication No. 2008/026331 Pamphlet of International Publication No. 2010/026843

  Therefore, the present invention solves the above-described conventional problems, and in particular, a thin physical quantity that can widen the detection range in the height direction (Z-axis direction) and can obtain more stable sensor sensitivity. It aims to provide a sensor.

The physical quantity sensor in the present invention is
An anchor portion that is fixedly supported, a movable portion that is displaced in the height direction, a support portion that is pivotably coupled to the anchor portion and the movable portion via a coupling portion that is elastically deformable, and the movable portion And a detector for detecting the displacement of
The support portion is provided with a leg portion that is displaced in a direction opposite to the displacement direction of the movable portion when the support portion is rotated by deformation of the connecting portion and the movable portion is displaced in the height direction. And
The leg is bent so that the leg is deformed from a state where it abuts against the surface of the opposing part facing the movable part in the height direction, and the movable part can be displaced further away from the surface of the opposing part. The portion is formed to be elastically deformable.

  In the present invention, the movable part can be translated in the height direction, and at this time, the leg part protrudes in the direction opposite to the displacement direction of the movable part.

  The displacement of the movable portion is initially caused mainly by elastic deformation of the connecting portion that connects between the movable portion and the support portion or between the support portion and the anchor portion (first displacement). When the movable part is displaced in the height direction due to elastic deformation of the connecting part, the leg part is displaced in the direction opposite to the displacement direction of the movable part, and at this time, the leg part is displaced to a position where it abuts against the surface of the opposing part. It is possible (end of the first displacement in the moving part). The first displacement of the movable part can be detected by the detection part.

  In the present invention, the leg portion is formed to be elastically deformable. For this reason, when a larger physical quantity is applied to the movable part from a state where the leg part is in contact with the surface of the opposing surface, the leg part bends and displaces the movable part further away from the surface of the opposing surface. (Second displacement). The second displacement of the movable part can be detected by the detection part.

  Thus, in the present invention, not only the displacement of the movable part (first displacement) due to the elastic deformation of the connecting part, but also the elastic deformation of the leg part is utilized after the leg part contacts the surface of the opposing part. The movable part can be further displaced in the height direction (second displacement), so that the movable range of the movable part can be expanded, and the detection range (measurement range) for a change in physical quantity can be expanded.

  In the present invention, the movable portion can be translated in the height direction, so that highly accurate sensor sensitivity can be obtained and a reduction in thickness can be realized. Furthermore, even if the movable part is displaced in the height direction, the structure is such that the movable part is supported by the legs, so that the movable range of the movable part can be stably controlled while floating inside, and damage to the movable part having a large mass Can be suppressed, and stable sensor sensitivity can be obtained.

  Further, in the present invention, by adopting a structure supported by a plurality of legs, stress can be distributed to the plurality of legs even when a strong physical quantity is applied, and a long life can be realized.

  In the present invention, the support portion includes a first connecting arm that connects the anchor portion and the movable portion via the connecting portion, and the leg that extends in the opposite direction from the anchor portion to the first connecting arm. When the support portion rotates, the first connecting arm and the leg portion are displaced in opposite directions around the connecting portion between the anchor portion and the first connecting arm. It is preferable. Accordingly, the movable portion can be displaced in the height direction with a simple mechanism, and the leg portion can be displaced in the direction opposite to the displacement direction of the movable portion.

  In the present invention, a plurality of the support portions including the leg portions are provided. The first connection arm provided on one of the support portions and the first connection arm provided on the other support portion. The leg portion provided in one of the first support portions and the leg portion provided in the other first support portion are interposed via the anchor portion. And extending in the opposite direction. In this way, a plurality of support portions are provided, and the movable portion is supported at a position where one support portion and the other support portion face each other via the anchor portion, and the leg portion extends in the opposite direction via the anchor portion. By making it come out, it is easy to translate the movable part in the height direction, and it is easy to obtain highly accurate sensor sensitivity.

  Further, in the present invention, separately from the support portion, a second connecting arm that extends in the opposite direction from the anchor portion to the first connecting arm and connects the anchor portion and the movable portion via the connecting portion. Is preferably provided. As a result, the support mechanism for the movable part has a more stable structure, and it is easy to effectively translate the movable part in the height direction, and more accurate sensor sensitivity can be obtained.

  Moreover, in this invention, it is preferable that the rear-end parts located on the opposite side to the connection position with the said movable part of the said 1st connection arm and the said 2nd connection arm are connected via the said connection part. As a result, when the first connecting arm and the second connecting arm rotate, the rear end portions of the first connecting arm and the second connecting arm are less likely to vary in the height direction, and more stably. The movable part can be translated in the height direction.

In the present invention, the anchor portion, the support portion, and the second connecting arm are all provided separately from the movable portion inside the movable portion,
The anchor portion is configured to include a left anchor portion and a right anchor portion that are spaced apart in the left-right direction (Y).
The support portion is connected to the left anchor portion via the connecting portion, and the first connecting arm extends forward (X1) and the leg portion extends rearward (X2) than the left anchor portion. A second support portion that is connected to the right anchor portion via the connecting portion, the first connecting arm extends rearward (X2) from the right anchor portion, and the leg portion extends forward (X1). Comprising
The second connection arm is located between the left anchor portion and the movable portion, and extends to the opposite direction to the first connection arm of the first support portion, and the left anchor portion and the right anchor portion. It is preferable to have a right-side second connecting arm that is positioned between the movable parts and extends in a direction opposite to the first connecting arm of the second support part.

  In the present invention, a central anchor portion is provided between the left anchor portion and the right anchor portion, and the first support portion is connected to both the central anchor portion and the left anchor portion via the connecting portion. Preferably, the second support part is connected to both the central anchor part and the right anchor part via the connecting part. At this time, the center anchor portion, the left anchor portion, and the right anchor portion are arranged on the same line extending in the left-right direction (Y), and face the movable portion in the height direction, and the facing portion is It is preferable that a fixing portion for fixing and supporting each anchor portion is provided on the side opposite to the provided side.

  In the present invention, as described above, the central anchor portion, the left anchor portion, and the right anchor portion are arranged on the same line extending in the left-right direction (Y), so that the fixed portion is distorted by heat or external force. Even when this occurs, the movable part can easily maintain the neutral position appropriately.

  In the present invention, the capacitance type detection unit may be disposed between the opposed unit and the movable unit that the leg unit approaches when the leg unit is displaced in a direction opposite to a displacement direction of the movable unit. Is preferably provided. As a result, a detection unit having a simple structure can be realized, and stable sensor sensitivity can be obtained.

  According to the configuration of the present invention, the detection range in the height direction (Z-axis direction) can be widened, and a thin physical quantity sensor capable of obtaining stable sensor sensitivity can be obtained.

The top view of the physical quantity sensor in 1st Embodiment of this invention, The perspective view which shows the state which the physical quantity sensor of 1st Embodiment has stopped, The perspective view which shows the state which the physical quantity sensor of 1st Embodiment is operate | moving, The perspective view which shows the state which the physical quantity sensor of 1st Embodiment is operate | moving, (A) is a side view of the physical quantity sensor of FIG. 2, (b) is a side view of the physical quantity sensor of FIG. (A) is a side view of the physical quantity sensor of FIG. 4, (b) is a side view of the physical quantity sensor showing a state where the leg portion is bent and the movable portion is displaced further upward from the state of (a), The partial expansion perspective view which shows the connection part vicinity shown in FIG. FIG. 1 is an enlarged partial plan view showing a part of FIG. The top view of the physical quantity sensor in 2nd Embodiment of this invention, It is a figure which shows the stopper structure of this invention, (a) is a partial enlarged plan view, (b) is sectional drawing of the aa line of (a), and the part which shows the state which the leg part contact | abutted to the stopper surface Sectional drawing, (c) is a partial sectional view showing a state in which the movable part is in contact with the stopper surface, (A) is a graph showing the relationship between the acceleration and capacitance of the physical quantity sensor (with legs) in this embodiment, and (b) is the acceleration and capacitance of the physical quantity sensor (without legs) in the comparative example. A graph showing the relationship.

  Regarding the physical quantity sensor shown in each figure, the Y-axis direction is the left-right direction, the Y1 direction is the left direction, the Y2 direction is the right direction, the X-axis direction is the front-rear direction, the X1 direction is the front, and the X2 direction is the rear. . Further, the direction perpendicular to both the Y direction and the X direction is the height direction (Z-axis direction).

  The physical quantity sensor 1 shown in FIG. 1 is formed from, for example, a silicon substrate that is a rectangular flat plate. That is, a planar resist layer corresponding to the shape of each member is formed on the silicon substrate, and the silicon substrate is etched by deep RIE (deep reactive ion etching) or the like at a portion where the resist layer does not exist. Each member is separated by cutting in the process. Therefore, each member which comprises the physical quantity sensor 1 is comprised within the range of the thickness of the surface of a silicon substrate, and a back surface. As shown in FIG. 2, when the physical quantity sensor is in a stationary state, the entire front surface and the entire back surface are located on the same surface, and there are no portions protruding from the front surface and the back surface.

  The physical quantity sensor 1 is very small. For example, the long sides 1a and 1b of the rectangle have a length of 1 mm or less, and the short sides 1c and 1d have a length of 0.8 mm or less. Furthermore, the thickness dimension is 0.1 mm or less.

  As shown in FIGS. 1 and 2, in the physical quantity sensor 1, an outer frame portion surrounded by rectangular long sides 1 a and 1 b and short sides 1 c and 1 d is a movable portion 2. The direction in which the long sides 1a, 1b extend is the front-rear direction, and the direction in which the short sides 1c, 1d extend is the left-right direction.

  As shown in FIGS. 1 and 2, two support parts 3 and 4 are provided inside the movable part 2. The planar shape of the support portions 3 and 4 is formed in a crank shape.

  As shown in FIG. 1, the 1st support part 3 is integrally formed with the 1st connection arm 3a extended in the front (X1), and the leg part 3b extended in back (X2). Here, the first connecting arm 3a is a side located forward (X1) from the connecting portions 12a and 12b, which are the connecting positions of the central anchor portion 5 and the left anchor portion 6, and the leg portion 3b is It is defined as the side located rearward (X2) from the connecting portions 12a and 12b.

  As shown in FIG. 1, the second support portion 4 is formed integrally with a first connecting arm 4a extending rearward (X2) and a leg portion 4b extending forward (X1). Here, the first connecting arm 4a is a side located rearward (X2) from the connecting portions 13a and 13b which are connecting positions with the central anchor portion 5 and the right anchor portion 7, and the leg portion 4b is It is defined as the side located forward (X1) from the connecting portions 13a and 13b.

  The first connecting arms 3a, 4a and the leg portions 3b, 4b are formed in a shape extending away from the respective anchor portions 5-7 and extending in a predetermined width dimension in parallel to the front-rear direction (X1-X2 direction). Has been. For example, as shown in FIG. 1, the width dimensions (dimensions in the Y1-Y2 direction) of the first connecting arms 3a, 4a and the leg portions 3b, 4b of the support portions 3, 4 are substantially the same.

  In this embodiment, the width of the leg portions 3b and 4b is formed so that the leg portions 3b and 4b can be elastically deformed as shown in FIG. 6B from the state of FIG.

  As shown in FIG. 1, the 1st support part 3 and the 2nd support part 4 are formed in point symmetry. Therefore, when viewed from the anchor portions 5 to 7, the extending direction of the first connecting arm 3 a of the first support portion 3 and the first connecting arm 4 a of the second support portion 4, and the leg portion 3 b of the first support portion 3, The extending directions of the leg portions 4b of the second support portion 4 are reversed.

  As shown in FIG. 1, a central anchor portion 5, a left anchor portion 6, and a right anchor portion 7 are provided inside the movable portion 2. As shown in FIG. 1, when the horizontal center line Ox is a line extending in the left-right direction (Y) at the midpoint between the short side 1c and the short side 1d of the physical quantity sensor 1, the center anchor portion 5, the left anchor portion 6 and A midpoint that bisects each of the right anchor portions 7 in the front-rear direction is located on the horizontal center line Ox. The width dimension in the front-rear direction (X) of the center anchor portion 5, the left anchor portion 6, and the right anchor portion 7 is substantially the same.

For example, the anchor portions 5 to 7 are fixedly supported by a fixing portion (supporting substrate) 10 shown in FIG. The fixing portion 10 is, for example, a silicon substrate, and an oxide insulating layer (SiO ₂ layer) (not shown) is interposed between the anchor portions 5 to 7 and the fixing portion 10. The silicon substrate constituting the fixed portion 10, the oxide insulating layer, the movable portion 2, the support portions 3 and 4, the anchor portions 5 to 7 and the like shown in FIG. 1 is, for example, an SOI substrate. In the stationary state shown in FIG. 5A, the interval T1 between the movable portion 2 and the fixed portion 10 is about 1 to 5 μm. In FIG. 5A, the intervals T1 and T2 with respect to the thickness of the movable portion 2 are illustrated in a different manner from the actual scale.

  As shown in FIGS. 1 and 2, the movable portion 2, the support portions 3 and 4, and the anchor portions 5 to 7 are formed separately from each other. Among these, the oxide insulating layer described above is interposed between each anchor portion 5-7 and the fixed portion 10, and each anchor portion 5-7 is fixedly supported by the fixed portion 10, but is movable. There is no oxide insulating layer between the part 2 and each support part 3, 4 and the fixed part 10, and there is a space between the movable part 2 and each support part 3, 4 and the fixed part 10. (See FIG. 5 (a)).

  As shown in FIG. 1, the distal end portion of the first connecting arm 3 a of the first support portion 3 and the movable portion 2 are rotatably connected at a connecting portion 11 a, and the first connecting arm of the second support portion 4 is connected. The front end portion of 4a and the movable portion 2 are rotatably connected at a connecting portion 11b.

  As shown in FIG. 1, the first connecting arm 3 a of the first support portion 3 is divided into two forks at a position close to the left anchor portion 6, and a portion positioned between the left anchor portion 6 and the central anchor portion 5. The center anchor portion 5 and the left anchor portion 6 are rotatably connected at the connecting portions 12a and 12b. Further, as shown in FIG. 1, the first connecting arm 4 a of the second support portion 4 is divided into two forks at a position close to the right anchor portion 7, and is located between the right anchor portion 7 and the central anchor portion 5. And the central anchor portion 5 and the right anchor portion 7 are rotatably connected at connecting portions 13a and 13b.

  Further, in the embodiment shown in FIG. 1, a second left connecting arm 14 formed separately from the movable portion 2 and the left anchor portion 6 is provided behind the left anchor portion 6 (X2). A right second connecting arm 15 formed separately from the movable portion 2 and the right anchor portion 7 is provided in the front (X1). Both the left second connecting arm 14 and the right second connecting arm 15 are formed inside the movable portion 2. The left second connecting arm 14 and the right second connecting arm 15 are formed point-symmetrically. The left second connecting arm 14 and the right second connecting arm 15 extend away from the left anchor portion 6 and the right anchor portion 7 with a predetermined width in parallel to the front-rear direction (X1-X2 direction). Is formed. The width dimension (dimension in the Y1-Y2 direction) of the left second connecting arm 14 and the right second connecting arm 15 is preferably the same as the width dimension of the first connecting arms 3a and 4a.

  And as shown in FIG. 1, the front-end | tip part of the left side 2nd connection arm 14 and the movable part 2 are rotatably connected in the connection part 16a. Moreover, the front-end | tip part of the right side 2nd connection arm 15 and the movable part 2 are rotatably connected in the connection part 16b. As shown in FIG. 1, the left second connecting arm 14 and the left anchor portion 6 are rotatably connected at a connecting portion 17a. Further, the right second connecting arm 15 and the right anchor portion 7 are rotatably connected at a connecting portion 17b.

  As shown in FIG. 1, the first connecting arm 3 a and the left second connecting arm 14 of the first support portion 3 both have rear end portions 3 c that extend at a position on the left side (Y 1) with respect to the left anchor portion 6. 14a, and the rear end portion 3c of the first connecting arm 3a and the rear end portion 14a of the left second connecting arm 14 are arranged to face each other with a predetermined interval. And between the rear-end part 3c of the 1st connection arm 3a and the rear-end part 14a of the left side 2nd connection arm 14 is connected via the connection part 18a. As shown in FIG. 1, both the first connecting arm 4 a and the right second connecting arm 15 of the second support portion 4 extend at a position on the right side (Y2) with respect to the right anchor portion 7. 15a, and the rear end portion 4c of the first connecting arm 4a and the rear end portion 15a of the right second connecting arm 15 are opposed to each other with a predetermined interval. And between the rear-end part 4c of the 1st connection arm 4a and the rear-end part 15a of the right side 2nd connection arm 15 is connected via the connection part 18b.

  Here, the length in the X1-X2 direction from the front end portion of the first connecting arm 3a of the first support portion 3 to the rear end portion 3c, the rear from the front end portion of the first connecting arm 4a of the second support portion 4. The length dimension in the X1-X2 direction to the end portion 4c, the length dimension in the X1-X2 direction from the front end portion of the left second connection arm 14 to the rear end portion 14a, and the right second connection arm 15 The length dimension in the X1-X2 direction from the front end part to the rear end part 15a is adjusted to the same dimension.

FIG. 7 is a partially enlarged perspective view showing the vicinity of the connecting portion 16b shown in FIG. 1 in an enlarged manner.
As shown in FIG. 7, in the connecting portion 16 b, a groove 19 is formed in the movable portion 2, and an elastically deformable torsion that connects the right second connecting arm 15 and the movable portion 2 inside the groove 19. A bar (spring part) 20a is provided. The torsion bar 20 a is formed of silicon, like the movable portion 2 and the right second connecting arm 15. That is, when the rectangular silicon substrate is etched to separate the movable part 2 and the right second connecting arm 15, a part of the silicon substrate is left so as to connect the movable part 2 and the right second connecting arm 15. The torsion bar 20a is formed by processing silicon into a prismatic shape. In other words, the portion of the silicon substrate that becomes the torsion bar 20a is cut out narrowly by etching so that the spring property can be provided.

  The structure shown in FIG. 7 is the same in the connecting portions 11a, 11b, and 16a shown in FIG.

  FIG. 8 is a partially enlarged plan view showing the central anchor portion 5, the right anchor portion 7, and the peripheral portion thereof in an enlarged manner.

  As shown in FIG. 8, in each of the connecting portions 12a, 13a, 13b, and 17b, torsion bars 20b to 20e that are elastically deformable are provided in the grooves, and the anchor portions 5 and 7 and the first connecting arms 3a, 4a, and The right second connecting arm 15 is connected via torsion bars 20b to 20e. Further, the connecting portions 12b and 17a of the left anchor portion 6 and the first connecting arm 3a and the left second connecting arm 14 which are not shown are also formed in the same structure as in FIG.

  As shown in FIG. 8, the connecting portion 18b located between the rear end portion 15a of the right second connecting arm 15 and the rear end portion 4c of the first connecting arm 4a of the second support portion 4 is bent in the groove 21. The spring portion 22 is provided, one end of the spring portion 22 being the rear end portion 15a of the right second connecting arm 15 and the other end of the spring portion 22 being the first connecting arm 4a of the second support portion 4. Is connected to the rear end 4c. The reason why the spring portion 22 detours without extending in parallel in the front-rear direction (X) is to increase the length of the narrow spring portion 22 to reduce the spring constant, and the first connecting arms 3a, 4a and second This is because the connecting arms 14 and 15 are not firmly connected. Moreover, the spring part provided in connection part 18a, 18b is provided coaxially in the left-right direction (Y). Moreover, the spring part provided in the connection part 18a and the spring part provided in the connection part 18b are formed in point symmetry.

  As the torsion bars 20a to 20e and the spring portion 22 are twisted and deformed, the connecting arms can be rotated with respect to the movable portion 2 and the anchor portions 5 to 7. Further, since the silicon forming the torsion bars 20a to 20e and the spring part 22 is an elastic material, when an external force is not acting on the movable part 2 or the like, as shown in FIG. 1 and FIG. By the elastic restoring force of 20a-20e and the spring part 22, it restore | restores so that the surface of the movable part 2, and the surface of each connection arm and each leg part may become the same surface.

  As shown in FIG. 5A, the physical quantity sensor 1 is provided with a fixed portion 10 on one side and a facing portion 30 on the other side which are separated from the movable portion 2 in the height direction. In the stationary state of FIG. 5A, the interval T2 between the movable portion 2 and the facing portion 30 is about 1 to 5 μm.

  Although not shown in FIG. 5A, a fixed electrode is provided on the surface 30 a of the facing portion 30. The facing portion 30 is, for example, a silicon substrate, and the fixed electrode is formed by sputtering or plating a conductive metal material on the surface 30a of the facing portion 30 via an insulating layer.

  A movable electrode (not shown) facing the fixed electrode formed on the facing portion 30 is formed on the surface (lower surface) 2a of the movable portion 2 through an insulating layer by sputtering or plating. Alternatively, when the movable portion 2 is formed of a conductive material such as a low resistance silicon substrate, the movable portion 2 itself can be used as a movable electrode.

  This physical quantity sensor 1 is shown in FIG. 2 and FIG. 5 (a) by an elastic restoring force of a torsion bar and a spring part provided in each connecting part when no force (acceleration etc.) is applied from the outside. Thus, the state where the surface of all the parts became the same plane is maintained.

  When acceleration is applied to the physical quantity sensor 1 from the outside, for example, the acceleration acts on the movable portion 2 and the anchor portions 5 to 7. At this time, the movable part 2 tries to stay in the absolute space by the inertial force, and as a result, the movable part 2 moves relative to each of the anchor parts 5 to 7 in a direction opposite to the direction in which the acceleration acts.

  3 and FIG. 5B show operations when downward acceleration is applied to the anchor portions 5 to 7, the fixed portion 10, and the facing portion 30. At this time, the movable portion 2 is displaced in the height direction around the coupling portions 12a and 12b so that the movable portion 2 is displaced upward from the stationary position of FIGS. 2 and 5A due to inertial force. The second support portion 4 rotates in the height direction about the connecting portions 13a and 13b, the left second connecting arm 14 rotates in the height direction about the connecting portion 17a, The two connecting arms 15 rotate in the height direction around the connecting portion 17b. During this rotation operation, the torsion bars provided in the connecting portions 11a, 11b, 12a, 12b, 13a, 13b, 16a, 16b, 17a, 17b are torsionally deformed (elastically deformed). Further, as shown in FIGS. 1, 3, and 5 (b), the gap between the rear end portion 14 a of the left second connecting arm 14 and the rear end portion 3 c of the first connecting arm 3 a of the first support portion 3 is The spring portion (connecting portion 18b) is connected between the rear end portion 15a of the right second connecting arm 15 and the rear end portion 4c of the first connecting arm 4a of the second support portion 4. It is connected by. Therefore, when the movable portion 2 is displaced in the height direction as shown in FIGS. 3 and 5B, the rear end portions 14a and 15a of the second connecting arms 14 and 15 are caused by the elastic deformation of the spring portions. It is possible to suppress variations in the height positions of the rear end portions 3c and 4c of the first connecting arms 3a and 4a.

  The movable part 2 can be effectively translated in the height direction by the support mechanism of the movable part 2 of the present embodiment.

  In the present embodiment, as shown in FIGS. 3 and 5B, the first support portion 3 rotates in the height direction around the connecting portions 12a and 12b, and the second support portion 4 is connected to the connecting portions 13a and 12a. When pivoting in the height direction about 13b, the distal ends of the first connecting arms 3a, 4a are displaced upward, while the distal ends of the legs 3b, 4b are displaced downward. As shown in FIG. 3 and FIG. 5B, the tip portions 31 and 32 of the leg portions 3 b and 4 b protrude downward from the positions of the anchor portions 5 to 7.

  When the movable portion 2 is further displaced upward due to acceleration, the anchor portions 5 to 7 of the distal end portions 31 and 32 of the leg portions 3b and 4b are further rotated by the first support portion 3 and the second support portion 4. The amount of protrusion from the lens is further increased (see FIGS. 4 and 6A). At this time, before the movable part 2 comes into contact with the surface 10a of the fixed part 10, the tip parts 31 and 32 of the legs 3b and 4b come into contact with the surface 30a of the facing part 30 as shown in FIG. . That is, the movable part 2 does not contact the surface 10 a of the fixed part 10.

  Thus, in the present embodiment, as shown in the state of FIG. 5A to the state of FIG. 6A, the movable portion 2 and the support portions 3 and 4, and the support portions 3 and 4 and the anchor portions, respectively. When the movable portion 2 is displaced in the height direction (Z-axis direction) due to elastic deformation at each of the connecting portions that connect the portions 5 to 7, the legs 3b and 4b are displaced in the direction opposite to the displacement of the movable portion 2. However, since the acting acceleration increases, the amount of downward protrusion of the leg portions 3b and 4b increases, and the leg portions 3b and 4b eventually contact the surface 30a of the facing portion 30. State (end of first displacement). The first displacement of the movable part 2 is the electrostatic force at the detection part 36 (see FIGS. 5A to 6A) composed of the movable part 2 and a fixed electrode provided on the surface 30a of the facing part 30. Detection can be performed based on a change in capacitance.

  FIG. 11A shows the relationship between the acceleration when the acceleration is applied in the height direction (Z-axis direction) using the physical quantity sensor 1 in the present embodiment and the capacitance detected by the detection unit 36. It is a graph. FIG. 11B is a graph showing the relationship between the acceleration when the acceleration is applied in the height direction (Z-axis direction) using the physical quantity sensor in the comparative example and the capacitance detected by the detection unit. is there.

  Here, the change in capacitance with respect to the acceleration in FIGS. 11A and 11B is an example. Further, the comparative example has a configuration without the leg portions 3b and 4b (for example, a configuration as shown in Patent Document 1) unlike the present embodiment.

  As shown in FIG. 11 (a), in this embodiment, when the acceleration gradually increases, the movable part 2 is gradually opposed to the fixed electrode as shown in FIGS. 5 (a) to 6 (a). The electrostatic capacity gradually decreases as the distance from the surface 30a of the portion 30 increases. As shown in FIG. 11B, also in the comparative example, the change in the capacitance with respect to the acceleration has shown the same behavior as in the present embodiment of FIG. 11A so far. That is, in this embodiment, since the sensor sensitivity is high in the reduction speed range with high accuracy, it has performance necessary for acceleration detection in this acceleration range.

  However, in the case of the comparative example, once the movable part 2 comes into contact with a stopper surface (not shown), the movable part 2 cannot be displaced in the height direction even if the acceleration further increases. As shown in FIG. 4, in the comparative example without the leg portions 3b and 4b, the acceleration range that causes the capacitance change is very narrow, that is, the detection range (measurement range) is very narrow.

  On the other hand, in this embodiment, when a further downward acceleration is applied from the state in which the legs 3b and 4b are in contact with the surface 30a of the facing portion 30 as shown in FIG. Since the movable part 2 tends to lift upward in the figure, the support parts 3 and 4 further rotate. At this time, not only the elastic deformation at each connecting portion but also the leg portions 3b and 4b formed so as to be elastically deformable are bent as shown in FIG. The movable portion 2 can be displaced further upward from the height position in FIG. 6A (the position indicated by the dotted line in FIG. 6B) (second displacement). In the present embodiment, the second displacement of the movable unit 2 can be detected based on the capacitance change in the detection unit 36.

  As described above, in the present embodiment, not only the displacement in the height direction of the movable portion 2 but also the leg portions 3b and 4b after the leg portions 3b and 4b contact the surface 30a of the facing portion 30 are detected. The movable portion 2 can be further displaced using the elastic deformation (second displacement), and therefore the movable range in the height direction of the movable portion 2 can be expanded, as shown in FIG. Compared to the comparative example, the acceleration detection range (measurement range) can be expanded.

  In the present embodiment, a control unit (not shown) that detects a change in capacitance includes a calculation unit that calculates the acceleration in response to the change in capacitance. For example, as shown in FIG. Based on the capacitance change, for example, the first acceleration range A and the second acceleration range B can be obtained. As shown in FIGS. 5B and 6A, the first acceleration range A having a small acceleration is within a movable range in which the leg portions 3b and 4b move downward while the movable portion 2 is displaced upward. On the other hand, as shown in FIG. 6 (b), the second acceleration range B having a large acceleration is obtained by bending the elastically deformable leg portions 3b and 4b and moving the movable portion 2 upward. It can be obtained by changing the capacitance within the movable range of displacement.

  In this embodiment, as shown in FIGS. 2 to 4, 5, and 6, the movable part 2 can be translated in the height direction (Z), and high-accuracy sensor sensitivity can be obtained. And can be made thinner.

  Furthermore, in this embodiment, as shown in FIGS. 6A and 6B, the movable portion 2 is supported by the leg portions 3b and 4b when the movable portion 2 is displaced in the height direction (Z). Therefore, the movable part 2 can be kept floating in the space between the facing part 30 and the fixed part 10, damage to the movable part 2 having a large mass can be suppressed, and stable sensor sensitivity can be obtained. .

  In addition, as shown in FIGS. 6A and 6B, in the present embodiment, since the movable portion 2 is supported by the plurality of leg portions 3b and 4b, the plurality of leg portions even when a large acceleration is applied. Stress can be distributed to the portions 3b and 4b, damage to the legs 3b and 4b can be suppressed, and a long life can be realized.

  Note that the slope of the capacitance change graph and the detectable acceleration range (detection range) shown in FIG. 11A are examples, and the width of the legs 3b and 4b, the elastic force of each connecting portion, the movable portion 2 and It can be adjusted by changing the interval T2 between the facing portions 30 or the like.

  In the embodiment shown in FIG. 1, a central anchor portion 5, a left anchor portion 6, and a right anchor portion 7 are provided. And the center of each anchor part 5-7 is arrange | positioned on the horizontal centerline Ox extended in the left-right direction (Y). For this reason, each connection part 12a, 12b, 13a, 13b, 17a, 17b is not greatly separated in the front-back direction from the horizontal center line Ox. Thereby, for example, even when distortion due to heat or distortion due to external force occurs in the fixing portion 10 that fixes and supports the anchor portions 5 to 7, the connecting portions 12 a, 12 b, 13 a, 13 b, 17 a, and 17 b are greatly increased vertically. It can suppress movement. Therefore, it is possible to suppress the vertical displacement from the neutral posture in which no acceleration or the like is applied to the movable part 2, and it is possible to reduce the offset noise (the output based on the deviation from the neutral posture).

  Further, as shown in FIG. 9, the anchor portions may be only the left anchor portion 6 and the right anchor portion 7, and the central anchor portion 5 may be omitted. In FIG. 9, the same parts as those in FIG.

  FIG. 10 shows a stopper mechanism in the present embodiment. FIG. 10A is a partially enlarged plan view showing, for example, the vicinity of the leg 4b in an enlarged manner. FIGS. 10B and 10C are partial enlarged cross-sectional views of FIG. 10A taken along the line aa and viewed from the direction of the arrows. In the following, only the leg portion 4b will be described, but a similar stopper mechanism is also provided in the vicinity of the leg portion 3b.

  As shown in FIGS. 10A and 10B, the surface 30a of the facing portion 30 is provided with two projecting portions 41 and 42 that protrude from the surface of the height adjusting base 40 that rises in a certain region. And the surface 41a, 42a of each projection part 41, 42 is a stopper surface (henceforth called stopper surface 41a, 42a).

  As shown in FIG. 10A, the width of the stopper surfaces 41a and 42a is sufficiently smaller than the width of the leg 4b. In FIG. 10A, the stopper surface 41a is substantially circular, but the planar shape of the stopper surface 41a is not particularly limited. The “width dimension” of the stopper surface 41a is a dimension in the same direction as the width dimension of the leg portion 4b along the left-right direction (Y1-Y2). If the stopper surface 41a is circular as shown in FIG. The width of the stopper surface 41a can be about several μm.

  The formation method of the base 40 and the projection parts 41 and 42 is not limited. For example, the surface 30a of the facing portion 30 can be dug and formed by etching.

  As shown in FIGS. 10A and 10B, one of the two stopper surfaces 41a and 42a has a tip surface 32b and a lower surface (the opposing portion 30) with respect to the leg portion 4b. It is formed so as to face the inner side of the corner portion 32a where the facing surface 32c intersects.

  For this reason, as shown in FIG. 10B, when the leg portion 4b is displaced downward and the leg portion 4b comes into contact with the stopper surface 41a, the lower surface of the leg portion 4b (surface facing the facing portion 30) 32c. Is in contact with the stopper surface 41a at a position inside the corner 32a.

  FIG. 10 (c) shows a case where the movable part 2 comes into contact with the stopper surface 42a of the other protrusion 42 (the movable part 2 is displaced downward and the legs 3b and 4b are displaced upward). However, also in FIG. 10C, it is possible to appropriately reduce the contact area between the movable portion 2 and the stopper surface 42a.

  10 may be provided on the lower surface 32c of the leg portions 3b and 4b and the lower surface of the movable portion 2 instead of the surface 30a of the facing portion 30 instead of the surface 30a of the facing portion 30.

  The formation of the protruding stopper shown in FIG. 10 is optional, but the provision of the protruding stopper can effectively improve the sticking resistance.

  Although the detection unit 36 in this embodiment is a capacitance type, the configuration of the detection unit is not limited to the capacitance type. For example, the detection unit can be a piezoresistive type. In such a case, the piezo element is arranged near the tip of at least one of the leg portions 3b and 4b, or at least one of the connecting portions 11a, 11b, 12a, 12b, 13a, 13b, 16a, 16b, 17a, 17b, 18a, and 18b. Provide one. However, since the capacitance type is adopted, a simple and highly accurate configuration of the detection unit can be realized.

  This embodiment is applicable not only to acceleration sensors but also to general physical quantity sensors such as angular velocity sensors and impact sensors.

DESCRIPTION OF SYMBOLS 1 Physical quantity sensor 2 Movable part 3, 4 Support part 3a, 4a 1st connection arm 3b, 4b Leg part 5 Center anchor part 6 Left anchor part 7 Right anchor part 10 Fixed part 11a, 11b, 12a, 12b, 13a, 13b, 16a, 16b, 17a, 17b, 18a, 18b connecting portion 14, 15 second connecting arms 20a-20e torsion bar (spring portion)
22 Spring part 30 Opposite part 30a Opposite part surfaces 31, 32 Leg tip part 36 Detection part 41 42 Protrusion part 41a, 42a Stopper surface

Claims (9)

An anchor portion that is fixedly supported, a movable portion that is displaced in the height direction, a support portion that is pivotably coupled to the anchor portion and the movable portion via a coupling portion that is elastically deformable, and the movable portion And a detector for detecting the displacement of
The support portion is provided with a leg portion that is displaced in a direction opposite to the displacement direction of the movable portion when the support portion is rotated by deformation of the connecting portion and the movable portion is displaced in the height direction. And
The leg is bent so that the leg is deformed from a state where it abuts against the surface of the opposing part facing the movable part in the height direction, and the movable part can be displaced further away from the surface of the opposing part. A physical quantity sensor characterized in that the portion is formed to be elastically deformable.   The support portion includes a first connecting arm that connects the anchor portion and the movable portion via the connecting portion, and a leg portion that extends from the anchor portion in a direction opposite to the first connecting arm. The first connecting arm and the leg portion are displaced in opposite directions around the connecting portion between the anchor portion and the first connecting arm when the support portion rotates. Physical quantity sensor.   A plurality of the support portions including the leg portions are provided, and the first connection arm provided in one of the support portions and the first connection arm provided in the other support portion include the anchor portion. The leg portion provided in one of the first support portions and the leg portion provided in the other first support portion extend in the reverse direction via the anchor portion. The physical quantity sensor according to claim 2.   Apart from the support part, a second connection arm is provided that extends in the opposite direction from the anchor part to the first connection arm and connects the anchor part and the movable part via the connection part. The physical quantity sensor according to claim 2 or 3.   5. The physical quantity sensor according to claim 4, wherein rear end portions of the first connecting arm and the second connecting arm that are located on the opposite side of the connecting position with the movable portion are connected via the connecting portion. The anchor portion, the support portion, and the second connecting arm are all provided separately from the movable portion inside the movable portion,
The anchor portion is configured to include a left anchor portion and a right anchor portion that are spaced apart in the left-right direction (Y).
The support part is connected to the left anchor part via the connecting part, and the first support arm extends forward (X1) and the leg part extends rearward (X2) than the left anchor part. A second support portion that is connected to the right anchor portion via the connecting portion, the first connecting arm extends rearward (X2) from the right anchor portion, and the leg portion extends forward (X1). Comprising
The second connection arm is located between the left anchor portion and the movable portion, and extends to the opposite direction to the first connection arm of the first support portion, and the left anchor portion and the right anchor portion. 6. The physical quantity sensor according to claim 4, wherein the physical quantity sensor is configured to include a right-side second connection arm that is positioned between the movable parts and extends in a direction opposite to the first connection arm of the second support part.   A center anchor portion is provided between the left anchor portion and the right anchor portion, and the first support portion is connected to both the center anchor portion and the left anchor portion via the connecting portion, and The physical quantity sensor according to claim 6, wherein the support portion is connected to both the central anchor portion and the right anchor portion via the connecting portion.   The center anchor portion, the left anchor portion, and the right anchor portion are arranged on the same line extending in the left-right direction (Y), facing the movable portion in the height direction, and provided with the facing portion. The physical quantity sensor according to claim 7, wherein a fixing portion for fixing and supporting each anchor portion is provided on the side opposite to the side.   The electrostatic capacitance type detection unit is provided between the facing unit and the movable unit, which the leg unit approaches when the leg unit is displaced in a direction opposite to a displacement direction of the movable unit. The physical quantity sensor according to any one of 1 to 8.

Images