JP2007298385A - Electrostatic capacity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve detection accuracy in an electrostatic capacitance type sensor where the capacitance of detection parts changes, according to relative displacements of fixed electrodes and a movable electrode in the thickness directions. <P>SOLUTION: A semiconductor layer 2 is provided with the fixed electrodes 6A and 6B and the movable electrode 5, supported movably at an anchor part 3 via a beam part 4. The fixed electrodes 6A and 6B and the movable electrode 5 are made to face each other at intervals from one another to constitute the detection parts 8A and 8B. The electrostatic capacitance type sensor 1 detects prescribed physical quantities by detecting the capacitance at the detection parts 8A and 8B. The detection parts 8A and 8B detect the capacitance, corresponding to changes in areas facing each other, associated with displacements of the movable electrode 5 and the fixed electrodes 6A and 6B in the thickness directions due to the movements of the movable electrode 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a capacitance sensor that detects a predetermined physical quantity by detecting a capacitance between a fixed electrode and a movable electrode.

  Conventionally, a semiconductor substrate is processed using a known semiconductor process to form a structure in which the movable electrode is movably supported by the fixed portion via an elastic element. There is known a capacitance type sensor that can detect various physical quantities such as acceleration and angular velocity by detecting a change in capacitance between these electrodes. Reference 1).

The electrostatic capacitance sensor of Patent Document 1 is configured so that the movable electrode can move in the thickness direction of the sensor with respect to the fixed electrode, and the displacement between the layer formed on the surface of the movable electrode and the fixed electrode is reduced. A change in the electrostatic capacity is detected accordingly.
US Pat. No. 6,792,804

  However, since the electrostatic capacitance sensor of the above-mentioned Patent Document 1 configures the detection unit by causing a relatively thin layer formed on the surface of the movable electrode and the fixed electrode to face each other, the mutual facing area in the detection unit However, there is a problem that the detection accuracy is lowered due to the characteristic that the lines of electric force swell and the electric field lines swell.

  Therefore, an object of the present invention is to improve detection accuracy in a capacitive sensor in which the capacitance of a detection unit changes according to the relative displacement in the thickness direction between the fixed electrode and the movable electrode.

  According to the first aspect of the present invention, a fixed electrode formed on the semiconductor layer and a movable electrode formed on the semiconductor layer and movablely supported by a fixed portion of the semiconductor layer via a beam are provided. A detection unit is configured such that an electrode and a movable electrode are arranged to face each other with a gap, and a capacitance type sensor that detects a predetermined physical quantity by detecting capacitance at the detection unit, wherein the detection The unit is characterized in that it detects a capacitance according to a change in an opposing area caused by a shift in a thickness direction between the movable electrode and the fixed electrode due to an operation of the movable electrode.

  The invention according to claim 2 is characterized in that the movable electrode and the fixed electrode are shifted in the thickness direction while the movable electrode is in an initial position.

  According to a third aspect of the present invention, the detection unit is configured such that a comb tooth portion provided on the fixed electrode and a comb tooth portion provided on the movable electrode are engaged with each other.

  According to a fourth aspect of the present invention, in the detection unit, at least two comb teeth protruding in opposite directions are provided on one fixed electrode, and a comb of the fixed electrode is provided on one movable electrode. A comb tooth portion that meshes with the tooth portion is provided.

  In the invention of claim 5, the comb-tooth portions of the fixed electrode and the movable electrode are substantially along the direction in which the inertial force acting on the movable electrode is maximized among the directions orthogonal to the main detection direction by the detection unit. It is characterized by protruding.

  In the invention of claim 6, two detection parts are provided by making two different fixed electrodes face each other with respect to one movable electrode, and electrostatic detection is performed as a differential output of the two detection parts. Capacitance is detected, and the projecting direction of the comb-teeth portion of the fixed electrode and the projecting direction of the comb-teeth portion of the movable electrode are the same for the two detection units.

  The invention according to claim 7 is characterized in that the movable electrode is swingably supported via a beam.

  The invention according to claim 8 is characterized in that the movable electrode is supported so as to reciprocate in the thickness direction via a beam.

  The invention according to claim 9 is characterized in that the beam is meandered.

  In a tenth aspect of the present invention, a second detection unit is provided with another fixed electrode opposed to the movable electrode with a gap, and the second detection unit provides a gap between the movable electrode and the fixed electrode. A corresponding electrostatic capacity is detected.

  According to the present invention, in the capacitive sensor in which the capacitance of the detection unit changes according to the relative displacement in the thickness direction between the fixed electrode and the movable electrode, the fixed electrode and the movable electrode formed on the semiconductor layer Since the detection part is configured to face each other with a gap, a sufficient thickness can be secured at the part where the fixed electrode and the movable electrode face each other, and the detection accuracy can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  (First Embodiment) FIG. 1 is a plan view of a semiconductor layer of a capacitive sensor according to this embodiment, FIG. 2 is a partial sectional view of the capacitive sensor, and FIG. It is a figure which shows the detection part of a type | mold sensor, Comprising: (a) is a top view which expands and shows a part of detection part, (b) is AA sectional drawing of (a), FIG. It is a top view which shows the 2nd detection part of a type | formula sensor.

  As shown in FIG. 2, an electrostatic capacitance type sensor 1 (hereinafter simply referred to as sensor 1) according to the present embodiment has an insulating layer such as a glass substrate on both sides of a semiconductor layer 2 obtained by processing a semiconductor substrate. 20 and 21 are joined by anodic bonding or the like. A relatively shallow recess 22 is formed on the bonding surface between the semiconductor layer 2 and the insulating layers 20 and 21 (only the bonding surface between the semiconductor layer 2 and the insulating layer 21 in FIG. 2). The insulation and the operability of the movable electrode 5 are ensured.

  Further, as shown in FIG. 2, a conductor layer 23 is formed on the surface 20 a of the insulating layer 20 and is used as an electrode for acquiring the potential of each part of the semiconductor layer 2. In the present embodiment, a through hole 24 is formed in the insulating layer 20 by sandblasting or the like to expose a part of the surface of the semiconductor layer 2 (the surface on the insulating layer 20 side) and penetrate from the surface of the insulating layer 20. By forming a series of conductor layers 23 that are electrically connected over the inner peripheral surface of the hole 24 and the surface of the semiconductor layer 2, the potential of each part in the semiconductor layer 2 can be detected from the conductor layer 23. It is like that. The surface of the insulating layer 20 is preferably covered (molded) with a resin layer (not shown).

  Then, as shown in FIGS. 1 to 4 and the like, by forming the gap 10 in the semiconductor substrate by a known semiconductor process, the anchor portions 3 and 13, the beam portions 4 and 14, and the movable electrode 5 are formed on the semiconductor layer 2. , 15, fixed electrodes 6 </ b> A, 6 </ b> B, 16, a frame portion 7, and the like.

  As shown in FIG. 1, the semiconductor layer 2 is formed in a substantially rectangular shape as a whole in plan view, and the frame portion 7 has a frame with a substantially constant width along the four peripheral edges (four sides) of the semiconductor layer 2. It is provided in the shape.

  The gap 10 is formed by, for example, vertical etching (for example, reactive ion etching such as ICP (Inductively Coupled Plasma) processing), and wall surfaces on both sides of the gap 10 are perpendicular to the surface of the semiconductor layer 2. It is preferable that the wall surfaces face each other substantially in parallel.

  A columnar shape having a rectangular cross-section (substantially rectangular cross-section in the present embodiment) is provided inside the frame portion 7 so as to approach corners that are both ends of one side of the frame portion 7 (the short side on the left side in FIG. 1 in the present embodiment). The anchor portions 3 and 3 are provided in a pair, and a pair of beam portions 4 and 4 extend in a direction close to each other from the anchor portions 3 and 3, that is, in a direction substantially along one side of the frame portion 7. It is connected to the movable electrode 5 (the overhanging portion 5e) at a substantially central portion of one side of the frame portion 7.

  The beam portion 4 is configured as a beam that is thick in the thickness direction of the sensor 1 and has a thin rectangular (substantially rectangular) cross section that is thin in a direction orthogonal to the thickness direction (a direction along the surface of the sensor 1). Although depending on the overall size, as an example, the height in the thickness direction of the semiconductor layer 2 is 10 micrometers or more (500 micrometers or less), and the width along the surface of the semiconductor layer 2 is several micrometers ( About 3 to 10 micrometers).

  The movable electrode 5 is formed in a rectangular frame shape having a relatively large rectangular opening 5a in the center, and is disposed along the inner edge of the frame portion 7 inside the frame portion 7 with a gap 10 therebetween. Yes. In addition, in the opening part 5a of the movable electrode 5, the structure for constructing | assembling the 2nd detection part 9 which detects the motion of the movable electrode 15 of the one direction (FIG. 1 left-right direction) along the surface of the sensor 1 ( An anchor portion 13, a beam portion 14, a movable electrode 15, and a fixed electrode 16) are disposed. Such a structure will be described later.

  The movable electrode 5 has a base end side frame portion 5b extending substantially parallel to the beam portions 4 and 4, and has an overhang portion 5e protruding from the substantially central portion in the longitudinal direction to the frame portion 7 side. . The beam portions 4 and 4 are connected to the overhang portion 5e.

  Arm portions 5c, 5c extend from both longitudinal ends of the base end side frame portion 5b in a direction substantially orthogonal to the base end side frame portion 5b (that is, in a direction substantially parallel to the side of the frame portion 7). The distal end side frame portion 5d is provided so as to connect the distal ends of the arm portions 5c and 5c. The front end side frame portion 5d extends along the side opposite to the side where the beam portions 4 and 4 of the frame portion 7 are disposed, and is substantially orthogonal to the arm portions 5c and 5c.

  The movable electrode 5 is separated from the insulating layers 20 and 21 by the concave portions 22 formed on the front and back surfaces thereof, and is separated from other portions in the semiconductor layer 2 by the gap 10 formed in the semiconductor layer 2. That is, the sensor 1 according to the present embodiment has a structure in which the movable electrode 5 is movably supported by the anchor portion 3 as a fixed portion of the semiconductor layer 2 via the beam portions 4 and 4. In such a structure, the anchor portion 3, the beam portions 4, 4 and the movable electrode 5 are integrally configured as a part of the semiconductor layer 2, and the anchor portion 3, the beam portions 4, 4 and the movable electrode 5 The potential can be regarded as almost equipotential.

  The beam portions 4 and 4 function as spring elements that elastically moveably support the movable electrode 5 with respect to the frame portion 7. In the present embodiment, the beam portions 4 and 4 have a long cross section in the thickness direction of the sensor 1 (a cross section perpendicular to the extending axis of the beam portion 4). Since the electrode 5 is arranged so as to be shifted to one side in the width direction of the beam portions 4 and 4 (only on one side in this embodiment), the inertia acting on the movable electrode 5 when acceleration in the thickness direction acts on the sensor 1. The beam portions 4 and 4 are twisted by the force, and the movable electrode 5 swings around the beam portions 4 and 4. That is, in the present embodiment, the beam portions 4 and 4 function as a torsion beam (torsion beam).

  In such a configuration, the movable electrode 5 and the fixed electrodes 6A and 6B are displaced in the thickness direction due to the swing of the movable electrode 5, but in the present embodiment, in the detection units 8A and 8B, the displacement in the thickness direction is detected. The electrostatic capacity according to the change of the mutual opposing area of the movable electrode 5 (front end side frame portion 5d) and the fixed electrodes 6A and 6B is detected. In this case, the main detection direction of the detection units 8A and 8B is the thickness direction of the sensor 1 (the direction perpendicular to the paper surface in FIGS. 1 and 3A).

  Specifically, elongated fixed electrodes 6A and 6B are provided along the inner side and the outer side of the distal end side frame portion 5d of the movable electrode 5, respectively, and the comb teeth portion 5f of the movable electrode 5 and the combs of the fixed electrodes 6A and 6B are provided. The detecting portions 8A and 8B are configured by meshing with the tooth portion 6b.

  In each of the detection portions 8A and 8B, the size of the gap 10a between the comb teeth portions 5f and 6b is set to a constant value, and as shown in FIG. 3 (b), the sensor 1 of the front end side frame portion 5d. Capacitance corresponding to the mutually facing areas Aa and Ab between the movable electrode 5 and the fixed electrodes 6A and 6B that change with the vertical movement in the thickness direction is detected.

  Specifically, with respect to the detection unit 8A, when the movable electrode 5 moves upward in FIG. 3B, the capacitance Aa increases as the mutual facing area Aa between the movable electrode 5 and the fixed electrode 6A increases. On the other hand, when the movable electrode 5 moves downward, the capacitance decreases as the area Aa between the movable electrode 5 and the fixed electrode 6A decreases.

  In addition, with respect to the detection unit 8B, when the movable electrode 5 moves upward, the capacitance decreases as the mutual facing area Ab between the movable electrode 5 and the fixed electrode 6B decreases, while the movable electrode 5 moves downward. When moving in the direction, the capacitance increases as the opposing area Ab between the movable electrode 5 and the fixed electrode 6B increases.

  Then, the potentials of the fixed electrodes 6A and 6B and the potential of the movable electrode 5 are taken out separately via the conductor layer 23 (see FIG. 2) formed corresponding to each electrode, and from the potential difference between these electrodes. Capacitances of the detection units 8A and 8B are acquired, and differential outputs of the capacitances of the detection units 8A and 8B are used as detection values by the sensor 1. That is, it is possible to grasp the attitude of the movable electrode 5 from the capacitance values of the detection units 8A and 8B, and it is possible to grasp various physical quantities such as acceleration and angular acceleration.

  Here, in the present embodiment, the capacitances of the detection units 8A and 8B monotonously increase in one moving direction of the movable electrode 5 (one of the upward direction and the downward direction in FIG. 3B). However, the output characteristic is such that the movable electrode 5 and the fixed electrodes 6A and 6B are shifted in the thickness direction in a state where the movable electrode 5 (front end side frame portion 5d) is in the initial position. It is realized by arranging. If the movable electrode 5 is in the initial position and the movable electrode 5 and the fixed electrodes 6A and 6B are configured to face each other with the same thickness without being displaced from each other, the movable electrode 5 is directed upward. In both cases of moving and moving downward, the mutual facing area is reduced, and the moving direction of the movable electrode 5 cannot be grasped from the value (change) of the capacitance. Will occur.

  Moreover, in this embodiment, the inertia force which acts on the movable electrode 5 becomes the maximum among the directions orthogonal to the main detection direction (namely, thickness direction of the sensor 1) by the detection parts 8A and 8B. It is preferable to project (extend) substantially along the direction. By doing so, it is possible to suppress the detection error of the detection units 8A and 8B from occurring due to the size of the gap 10a being changed by the inertial force acting in a direction different from the main detection direction.

  In this embodiment, as described above, the anchor portions 13 and 13, the beam portions 14 and 14, the movable electrode 15, and the fixed electrodes 16 and 16 are provided in the opening 5 a of the movable electrode 5, and the movable electrode 15 is provided. And a part of the fixed electrodes 16 and 16 are opposed to each other with a gap 10b (FIG. 4) to form the second detection portions 9 and 9, and the second detection portions 9 and 9 detect the second detection portions 9 and 9. It is configured so that the displacement and acceleration of the movable electrode 15 can be detected in a direction different from the portions 8A and 8B.

  Specifically, as shown in FIG. 4, the movable electrode 15 includes a comb tooth portion 15 b that is elongated in a strip shape in a direction substantially perpendicular to the side from the center portion 15 a toward the center portion of one side of the frame portion 7. The plurality of comb teeth portions 15b are provided in parallel to each other at a constant pitch.

  On the other hand, the fixed electrode 16 includes a corner portion 16a provided close to the corner portion of the opening 5a, and an edge portion 16b extending in a strip shape from the corner portion 16a along one side of the frame portion 7, A comb tooth portion 16c extending toward the central portion 15a side of the movable electrode 15 is provided on the edge portion 16b. In the present embodiment, the plurality of comb teeth 16c are provided in parallel with each other at a constant pitch (the same pitch as the comb teeth 15b of the movable electrode 15), and the plurality of comb teeth 15b of the movable electrode 15 are provided. With a gap 10b.

  In the second detector 9, the gap 10 between the comb teeth 15b and 16c is set narrower on one side (gap 10b) and wider on the other side (gap 10c) than the comb teeth 15b. With the gap 10b on the narrow side as a detection gap, the capacitance that changes in accordance with the size of the gap 10b between the comb teeth 15b and 16c facing each other through the gap 10b is detected. Yes.

  The movable electrode 15 is movably supported by anchor portions 13 and 13 provided in the opening 5 a via beam portions 14 and 14, and the beam portions 14 and 14 are long in the thickness direction of the sensor 1 and in the width direction. By making the rectangular cross-sectional shape short in the (surface direction of the sensor 1), the movable electrode 15 is difficult to bend in the thickness direction of the sensor 1, and appropriately moving to meander the movable electrode 15 along the surface of the sensor 1. It is configured to be movable in one direction (left and right direction in FIG. 1).

  According to the present embodiment described above, the detection portions 8A and 8B cause changes in the opposing areas Aa and Ab due to the displacement of the movable electrode 5 and the fixed electrodes 6A and 6B in the thickness direction due to the operation of the movable electrode 5. Since the corresponding electrostatic capacity is detected, the linear function of the relative displacement between the movable electrode 5 and the fixed electrodes 6A and 6B, that is, the displacement (swinging angle) of the movable electrode 5 is detected. It becomes. Therefore, detection accuracy can be improved as compared with the case where the capacitance changes in inverse proportion to the square of the size of the gap by changing the size of the gap. In addition, since the movable electrodes 5 formed on the semiconductor layer 2 and the fixed electrodes 6A and 6B are opposed to each other to construct the detection units 8A and 8B, a wider area can be secured, and the lines of electric force can be secured. Since bending can be reduced, detection accuracy can be increased.

  Further, according to the present embodiment, since the movable electrode 5 and the fixed electrodes 6A and 6B are shifted in the thickness direction in a state where the movable electrode 5 is in the initial position, each detection direction is detected in one moving direction of the movable electrode 5. The capacitances of the portions 8A and 8B can be set so as to monotonously increase or monotonously decrease, so that the moving direction of the movable electrode 5 can be grasped from the change (increase / decrease) in the capacitance.

  In the present embodiment, in the detection units 8A and 8B, the comb teeth 6b provided on the fixed electrodes 6A and 6B and the comb teeth 5f provided on the movable electrode 5 are configured to mesh with each other. 5 and the fixed electrodes 6A and 6B can effectively increase the areas of the portions facing each other, thereby increasing the detection accuracy.

  Moreover, in this embodiment, the inertia force which acts on the movable electrode 5 becomes the maximum among the directions orthogonal to the main detection direction (namely, thickness direction of the sensor 1) by the detection parts 8A and 8B. Since it is configured to protrude substantially along the direction, it is possible to suppress a change in the size of the gap 10a due to the inertial force acting on the movable electrode 5, and thus to suppress occurrence of a detection error.

  In the present embodiment, the movable electrode 5 is supported by the anchor portion 3 as a fixed portion of the semiconductor layer 2 through the beam portion 4 so that the movable electrode 5 can swing. A configuration in which the fixed electrodes 6A and 6B are displaced in the thickness direction of the sensor 1 can be obtained as a relatively simple configuration.

  In the present embodiment, since the second detection units 9 and 9 that detect the displacement and acceleration of the movable electrode 15 in a direction different from the main detection direction by the detection units 8A and 8B are provided, acceleration and the like in a plurality of directions. Compared with the case where a sensor is separately provided in each direction to detect the above, downsizing can be achieved.

  In particular, in the present embodiment, the detection units 8A and 8B are formed in a portion of the movable electrode 5 that is separated from the torsion center (the central axis of the beam unit 4), and between the detection units 8A and 8B and the torsion center, Since the second detection units 9 and 9 are provided, the detection units 8A and 8B are arranged at positions far from the torsion center, and the detection units 8A and 8B are oscillated in the oscillating radial direction (left and right in FIG. 1). (Direction) can be reduced to improve detection accuracy (particularly linearity), and the detectors 8A and 8B are spaced apart from the torsion center, so that the detection units 8A and 8B are located between the torsion center. Since the generated dead space can be effectively used as a space for providing the second detection units 9 and 9, the sensor 1 can be configured more compactly.

  (Second Embodiment) FIG. 5 is a plan view of a semiconductor layer of a capacitive sensor according to this embodiment. The sensor 1A according to the present embodiment includes the same components as the sensor 1 according to the first embodiment. Therefore, below, the same code | symbol is provided to the same component and the overlapping description is abbreviate | omitted.

  In the sensor 1A according to the present embodiment, the detectors 8A1 and 8B also detect static electricity according to the change in the mutual facing area due to the displacement of the movable electrode 5A and the fixed electrodes 6A1 and 6B in the thickness direction by the operation of the movable electrode 5A. It is configured to detect the capacitance. Therefore, the same effect as the first embodiment can be obtained.

  However, in this embodiment, the protrusion direction (extension direction) of each comb-tooth part is made into the same direction about two detection part 8A1, 8B. Specifically, as shown in FIG. 5, both the fixed electrodes 6A1 and 6B project the comb-tooth portion from the right side to the left side in FIG. 5, and the comb-tooth portion of the movable electrode 5A from the left side in FIG. It protrudes toward the right side and meshes with each other. In such a configuration, the increase and decrease of the mutual facing area in the direction caused by the unintentional operation of the movable electrode 5A in the protruding direction of the comb tooth portion (left and right direction in FIG. 5) is the same for the two detection units 8A1 and 8B. Therefore, in the differential outputs of the detectors 8A1 and 8B, an error due to the increase / decrease in the mutual facing area can be canceled, and thus the detection accuracy can be improved.

  (Third Embodiment) FIG. 6 is a plan view of a semiconductor layer of a capacitive sensor according to this embodiment. The sensor 1B according to the present embodiment includes the same components as the sensor 1 according to the first embodiment. Therefore, below, the same code | symbol is provided to the same component and the overlapping description is abbreviate | omitted.

  The sensor 1B according to the present embodiment also uses the detection units 8A2 and 8B2 to detect electrostatic charges corresponding to a change in the opposing area due to a shift in the thickness direction between the movable electrode 5B and the fixed electrodes 6A2 and 6B2 due to the operation of the movable electrode 5B. It is configured to detect the capacity. Therefore, the same effect as the first embodiment can be obtained.

  However, in the sensor 1B according to the present embodiment, in the detection unit 8A2, the single fixed electrode 6A2 is provided with comb teeth 6b2 protruding (extending) in opposite directions (upward and downward in FIG. 6). The movable electrode 5B is provided with a comb tooth portion 5f2 that meshes with the comb tooth portion 6b2. Also in the detection unit 8B2, the single fixed electrode 6B2 is provided with comb teeth 6b2 protruding (extending) in opposite directions (upward and downward in FIG. 6) and meshed with these comb teeth 6b2. A comb tooth portion 5f2 is provided. Therefore, in such a configuration, in each of the detection units 8A2 and 8B2, one movable electrode 5B is provided with comb-tooth portions 5f2 and 5f2 that protrude in opposite directions.

  In such a configuration, when the movable electrode 5B is displaced upward in FIG. 6, the mutual opposing area increases in the portion where the upper comb teeth 6b2 and 5f2 in FIG. 6 are engaged, whereas the lower comb teeth in FIG. In the portion where 6b2 and 5f2 mesh with each other, the mutual facing area decreases. On the other hand, when the movable electrode 5B is displaced downward in FIG. 6, the area facing each other decreases in the portion where the upper comb teeth 6b2 and 5f2 in FIG. 6 are engaged, whereas the lower comb teeth 6b2 in FIG. In the portion where 5f2 meshes with each other, the mutual facing area increases. Therefore, according to the present embodiment, the increase or decrease in the mutual facing area is canceled for each of the detection units 8A2 and 8B2 both when the movable electrode 5B is displaced upward in FIG. 6 and when it is displaced downward in FIG. Thus, it is possible to cancel out an error associated with the increase / decrease of the mutual facing area, thereby improving the detection accuracy.

  Furthermore, in the present embodiment, the frame portion 7 supports the four corners of the substantially rectangular plate-like movable electrode 5B via the four beam portions 4B having a meandering structure, and the movable electrode 5B extends in the thickness direction of the sensor 1B. Reciprocation is possible. With this configuration, the amount of movement in the direction orthogonal to the thickness direction is reduced, and detection errors due to movement in the orthogonal direction can be reduced, so that the detection accuracy can be further increased.

  Further, when the movable electrode 5B is reciprocated in the thickness direction as described above, both ends that are symmetrical with respect to the center of gravity of the movable electrode 5B are supported by a plurality of beam portions so that the movable electrode 5B does not tilt. It is more preferable to support three or more points. In this respect, if the movable electrode 5B has a line-symmetric shape in the vertical and horizontal directions in FIG. 6 and supports the four corners as in this embodiment, the unintentional tilting of the movable electrode 5B can be more reliably performed. Can be suppressed. Moreover, there exists an advantage that it becomes easy to ensure the amount of bending by meandering the beam part 4B like this embodiment.

  (Fourth Embodiment) FIG. 7 is a plan view of a semiconductor layer of a capacitive sensor according to this embodiment. The sensor 1C according to the present embodiment includes the same components as the sensor 1 according to the first embodiment. Therefore, below, the same code | symbol is provided to the same component and the overlapping description is abbreviate | omitted.

  The sensor 1C according to the present embodiment is configured so that the movable electrode 5C can perform a reciprocating operation in the thickness direction of the sensor 1C and a reciprocating operation in at least one direction along the surface, and detects the operation in the thickness direction. The movable electrode 5C is shared by both the portions 8A3 and 8B3 and the second detection portions 9C and 9C that detect the movement in the surface direction.

  Specifically, substantially rectangular columnar anchor portions 3C, 3C are provided at positions close to each of two opposite sides (upper and lower sides in FIG. 7) of the frame portion 7, and the anchor portions 3C, 3C The movable electrode 5C is supported at four positions spaced apart from each other via the four meandering beam portions 4C, so that the movable electrode 5C is controlled in the thickness direction of the sensor 1C while suppressing the tilt of the movable electrode 5C. It is configured to be able to reciprocate in the vertical direction.

  Furthermore, the movable electrode 5C is provided with openings at four positions, which are up, down, left and right in FIG. 7 when viewed from the center, and four fixed electrodes 6A3, 6B3, 16C, and 16C are arranged in each opening with appropriate gaps. ing.

  A pair of fixed electrodes 6A3 and 6B3 along two opposite sides (two sides on the left and right in FIG. 7) of the four sides of the frame unit 7 are detection units 8A3 that detect the operation of the movable electrode 5C in the thickness direction of the sensor 1C. , 8B3. That is, the portion where the outer end surface 6c of the rod-like portion 6b3 of the fixed electrodes 6A3 and 6B3 and the inner end surface 5g of the outer frame portion 5f3 of the movable electrode 5C face each other with a gap detects the operation in the thickness direction of the sensor 1C. It becomes detection part 8A3, 8B3. In this manner, in each of the detection units 8A3 and 8B3, the fixed electrodes 6A3 and 6B3 are surrounded by the movable electrode 5C in a plan view, so that the fixed electrodes 6A3 and 6B3 and the movable electrode 5C can be Even in the case of deviation in the direction, the mutual facing area does not change, and detection errors due to the deviation can be suppressed.

  The other pair of fixed electrodes 16C and 16C are constituent elements of the second detectors 9C and 9C that detect the operation of the movable electrode 5C in one direction (vertical direction in FIG. 7) along the surface of the sensor 1C. Yes. That is, the portion where the outer end surface 16c of the fixed electrode 16C and the inner end surface 5i of the outer frame portion 5h of the movable electrode 5C face each other with a gap is the detection unit 9C that detects the vertical movement in FIG. Yes. Note that the second detection units 9C and 9C are also configured so that the fixed electrodes 6A3 and 6B3 are surrounded by the movable electrode 5C in a plan view, so that the fixed electrodes 6A3 and 6B3 and the movable electrode 5C are left and right in FIG. Even in the case of deviation in the direction, the mutual facing area does not change, and detection errors due to the deviation can be suppressed.

  According to the above embodiment, since the movable electrodes 5C can be shared by the detection units 8A3 and 8B3 and the second detection units 9C and 9C, the sensor 1C can be used as compared with the case where these are provided separately. Can be made smaller.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various modifications can be made.

The top view of the semiconductor layer of the electrostatic capacitance type sensor concerning 1st Embodiment of this invention. 1 is a cross-sectional view of a part of a capacitive sensor according to an embodiment of the present invention. It is a figure which shows the detection part of the electrostatic capacitance type sensor concerning embodiment of this invention, Comprising: (a) is a top view which expands and shows a part of detection part, (b) is AA of (a). Sectional drawing. The top view which shows the 2nd detection part of the electrostatic capacitance type sensor concerning 1st Embodiment of this invention. The top view of the semiconductor layer of the electrostatic capacitance type sensor concerning 2nd Embodiment of this invention. The top view of the semiconductor layer of the electrostatic capacitance type sensor concerning 3rd Embodiment of this invention. The top view of the semiconductor layer of the electrostatic capacitance type sensor concerning 4th Embodiment of this invention.

Explanation of symbols

1, 1A, 1B, 1C Capacitive sensor 2 Semiconductor layer 3, 3C Anchor part (fixed part)
4,4B, 4C Beam part (beam)
5, 5A, 5B, 5C Movable electrode 6A, 6B, 6A1, 6A2, 6B2, 6A3, 6B3 Fixed electrode 8A, 8B, 8A1, 8A2, 8B2, 8A3, 8B3 Detector 9, 9C Second detector 5f, 6b , 5f2, 6b2 comb teeth

Claims (10)

A fixed electrode formed in the semiconductor layer, and a movable electrode formed in the semiconductor layer and supported by a fixed portion of the semiconductor layer via a beam, and the fixed electrode and the movable electrode are mutually connected with a gap. A detection unit is configured to be opposed to each other, and is a capacitance type sensor that detects a predetermined physical quantity by detecting capacitance at the detection unit,
The detection unit detects a capacitance according to a change in an opposing area due to a shift in a thickness direction between the movable electrode and the fixed electrode due to an operation of the movable electrode.   The capacitive sensor according to claim 1, wherein the movable electrode and the fixed electrode are shifted in a thickness direction in a state where the movable electrode is in an initial position.   The electrostatic capacitance according to claim 1, wherein the detection unit is configured such that a comb tooth portion provided on the fixed electrode and a comb tooth portion provided on the movable electrode are engaged with each other. Type sensor.   In the detection unit, one fixed electrode is provided with at least two comb teeth protruding in opposite directions, and one movable electrode is provided with a comb tooth engaging with the comb teeth of the fixed electrode. The capacitive sensor according to claim 3.   The comb-tooth portion of the fixed electrode and the movable electrode is protruded substantially along a direction in which an inertial force acting on the movable electrode is maximized in a direction orthogonal to a main detection direction by the detection unit. Item 5. The capacitive sensor according to Item 3 or 4. Two detection units are provided by facing two different fixed electrodes to one movable electrode, and capacitance is detected as a differential output of the two detection units,
6. The protruding direction of the comb-tooth portion of the fixed electrode and the protruding direction of the comb-tooth portion of the movable electrode are the same for the two detection portions. Capacitive sensor.   The capacitive sensor according to claim 1, wherein the movable electrode is supported so as to be swingable via a beam.   The capacitive sensor according to claim 1, wherein the movable electrode is supported so as to be capable of reciprocating in a thickness direction via a beam.   The capacitive sensor according to any one of claims 1 to 8, wherein the beam is meandered. A second detection unit is provided with another fixed electrode opposed to the movable electrode with a gap, and the second detection unit detects a capacitance according to the gap between the movable electrode and the fixed electrode. The capacitive sensor according to any one of claims 1 to 9, characterized in that

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