JP5352865B2 - Acceleration sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acceleration sensor capable of detecting a wide range of acceleration without contact with any component members in a region of large impressed acceleration. <P>SOLUTION: The acceleration sensor 100 includes a substrate 1, a displacement member 3 supported on a surface of the substrate 1 movably in a thickness direction of the substrate 1 to the substrate 1 to have a movable electrode 7, and a fixed electrode 6 arranged so as to face to the movable electrode 7 to generate electrostatic force in between with the movable electrodes 7, wherein a facing area between the movable electrode 7 and the fixed electrode 6 is constant even if the displacement member 3 displaces to the thickness direction of the substrate 1 in a region of small acceleration while the facing area between the movable electrode 7 and the fixed electrode 6 is composed to vary when the displace member 3 displaces to the thickness direction of substrate 1 in a region of large acceleration. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

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

  2. Description of the Related Art Conventionally, there is known an acceleration sensor that detects acceleration based on a capacitance change between electrodes accompanying acceleration application. In this capacitance type acceleration sensor, an acceleration sensor for detecting a wide range of acceleration has been proposed.

  For example, JP 2004-286554 A (Patent Document 1) proposes an acceleration sensor for detecting a wide acceleration range with one sensor. The acceleration sensor of this publication has a plurality of beams that are connected to the movable electrode and are displaced according to the acceleration. The spring constants of the beams are different. Three beams having different lengths are formed as a plurality of beams having different spring constants. Each of these three beams is constituted by a two-sheet structure and has an interval inside.

  This acceleration sensor is displaced from the longest beam according to the acceleration. When a low G (low acceleration) is applied, the longest beam is displaced, and when it is displaced to the internal distance, the two beams are in contact with each other, so that the longest beam is not displaced further. When the acceleration is higher than the low G, the second longest beam is displaced, and when the acceleration is further increased, the shortest beam is displaced. As the three beams having different lengths are displaced in this way, the distance between the fixed electrode and the movable electrode changes following a range from low G to high G (high acceleration). This publication states that a wide range of acceleration can be detected with a small size.

JP 2004-286554 A

  In the acceleration sensor of the above publication, in order to detect a wide range of acceleration, when the acceleration is higher than low G, the beam contacts from the longest beam. When the beams come into contact with each other, there is a problem that a malfunction due to an impact and a malfunction due to adsorption between the beams occur.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an acceleration sensor capable of detecting a wide range of acceleration without contacting a component member in a region where the applied acceleration is large.

The acceleration sensor of the present invention is disposed on the substrate, the displacement member supported on the surface of the substrate so as to be displaceable in the thickness direction of the substrate and having a movable electrode, the movable electrode, and the movable electrode. And a fixed electrode for generating an electrostatic force between the movable electrode and the fixed electrode in a region where the acceleration is small, even if the displacement member is displaced in the thickness direction of the substrate, When the displacement member is displaced in the thickness direction of the substrate in a region where acceleration is large, the facing area between the movable electrode and the fixed electrode is changed. The movable electrode includes a plurality of movable electrode portions separated from each other, the fixed electrode includes a plurality of fixed electrode portions separated from each other, and the plurality of movable electrode portions and the plurality of fixed electrode portions are opposed to each other. There are a plurality of pairs of movable electrode portions and fixed electrode portions arranged, and in a region where acceleration is small, even if the displacement member is displaced in the thickness direction of the substrate, a plurality of pairs of movable electrode portions and fixed electrode portions When the displacement member is displaced in the thickness direction of the substrate in a region where the acceleration is constant and the acceleration is large, the total of the opposing areas of the plurality of sets of movable electrode portions and fixed electrode portions changes. ing. The plurality of sets include a set in which the opposed area between the movable electrode portion and the fixed electrode portion is increased by the displacement of the movable electrode portion in the thickness direction of the substrate in a region where the acceleration is small, and the movable electrode portion and the fixed electrode portion. And the set having a smaller opposing area.

  According to the acceleration sensor of the present invention, in the region where the acceleration is small, even if the displacement member is displaced in the thickness direction of the substrate, the facing area between the movable electrode and the fixed electrode is constant, and the displacement member is in the region where the acceleration is large. When the substrate is displaced in the thickness direction, the facing area between the movable electrode and the fixed electrode changes, so that the electrostatic force generated according to the change in capacitance due to the change in the facing area between the fixed electrode and the movable electrode is applied. A wide range of accelerations can be detected without contacting the components in a region where the acceleration is large.

It is a schematic plan view of the acceleration sensor in Embodiment 1 of this invention. It is a schematic sectional drawing in alignment with the II-II line of FIG. It is a schematic sectional drawing in alignment with the III-III line of FIG. It is a schematic sectional drawing which follows the IV-IV line of FIG. It is a schematic plan view of the acceleration sensor in Embodiment 1 of this invention, Comprising: It is a schematic plan view which shows the equipotential structural member by the same hatching. It is a schematic sectional drawing in alignment with the VI-VI line of FIG. It is a schematic sectional drawing which shows the 1st process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, Comprising: The cross-sectional position of (A), (B) and (C) is FIG.2, FIG.3 and FIG. 4 corresponding to the cross-sectional position. It is a schematic sectional drawing which shows the 2nd process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, Comprising: The cross-sectional position of (A), (B) and (C) is FIG.2, FIG.3 and FIG. 4 corresponding to the cross-sectional position. It is a schematic sectional drawing which shows the 3rd process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, Comprising: The cross-sectional position of (A), (B) and (C) is FIG.2, FIG.3 and FIG. 4 corresponding to the cross-sectional position. It is a schematic sectional drawing which shows the 4th process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, Comprising: The cross-sectional position of (A), (B) and (C) is FIG.2, FIG.3 and FIG. 4 corresponding to the cross-sectional position. It is a schematic sectional drawing which shows the 5th process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, Comprising: The cross-sectional position of (A), (B) and (C) is FIG.2, FIG.3 and FIG. 4 corresponding to the cross-sectional position. It is a schematic sectional drawing which shows the 6th process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, Comprising: The cross-sectional position of (A), (B) and (C) is FIG.2, FIG.3 and FIG. 4 corresponding to the cross-sectional position. It is a schematic sectional drawing which shows the 7th process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, Comprising: The cross-sectional position of (A), (B) and (C) is FIG.2, FIG.3 and FIG. 4 corresponding to the cross-sectional position. It is a schematic sectional drawing which shows the 8th process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, Comprising: The cross-sectional position of (A), (B) and (C) is FIG.2, FIG.3 and FIG. 4 corresponding to the cross-sectional position. It is a schematic sectional drawing which shows the 9th process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, Comprising: The cross-sectional position of (A), (B) and (C) is FIG.2, FIG.3 and FIG. 4 corresponding to the cross-sectional position. It is a schematic sectional drawing which shows the 10th process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, Comprising: The cross-sectional position of (A), (B) and (C) is FIG.2, FIG.3 and FIG. 4 corresponding to the cross-sectional position. It is a schematic sectional drawing which shows the 11th process of the manufacturing method of the acceleration sensor in Embodiment 1 of this invention, Comprising: The cross-sectional position of (A), (B) and (C) is FIG.2, FIG.3 and FIG. 4 corresponding to the cross-sectional position. It is a schematic sectional drawing which shows the state in which the acceleration was applied to the acceleration sensor in Embodiment 1 of this invention, Comprising: The cross-sectional position respond | corresponds to FIG. It is the schematic which shows arrangement | positioning with the fixed electrode of the acceleration sensor in Embodiment 1 of this invention, and a movable electrode. It is a schematic sectional drawing which shows the relative positional relationship of the stationary electrode and movable electrode of the acceleration sensor in Embodiment 1 of this invention, Comprising: The state (A) which the movable electrode moved beyond the stationary electrode in the board | substrate direction, A state in which the movable electrode moves in a range not exceeding the fixed electrode in the substrate direction (B), a state in which the movable electrode does not move (C), and a state in which the movable electrode moves in a range not exceeding the fixed electrode in the direction opposite to the substrate (D ) Is a schematic cross-sectional view showing a state (E) in which the movable electrode moves beyond the fixed electrode in the direction opposite to the substrate. It is a figure which shows the tendency of the electrostatic capacitance with respect to the displacement of a movable electrode at the time of considering with the typical parallel plate model of the acceleration sensor in Embodiment 1 of this invention. It is a figure which shows the tendency of the displacement differential of the electrostatic capacitance with respect to the displacement of a movable electrode at the time of considering with the typical parallel plate model of the acceleration sensor in Embodiment 1 of this invention, and the produced electrostatic force. It is a figure which shows the tendency of the electrostatic capacitance with respect to the displacement of a movable electrode at the time of considering the influence of the electric field distribution in the flat plate edge part of the acceleration sensor in Embodiment 1 of this invention. It is a figure which shows the tendency of the electrostatic capacity displacement differentiation with respect to the displacement of a movable electrode when the influence of the electric field distribution in the flat plate edge part of the acceleration sensor in Embodiment 1 of this invention is considered, and the electrostatic force which arises. It is a figure which shows the relationship between the applied acceleration of the acceleration sensor in Embodiment 1 of this invention, and the displacement of an inertial mass body. It is a schematic plan view of Modification 1 of the acceleration sensor according to Embodiment 1 of the present invention. It is a schematic sectional drawing of the modification 2 of the acceleration sensor in Embodiment 1 of this invention, Comprising: The cross-sectional position respond | corresponds to the cross-sectional position of FIG. It is a schematic plan view of Modification 3 of the acceleration sensor according to Embodiment 1 of the present invention. It is a schematic sectional drawing which follows the XXIX-XXIX line | wire of FIG. It is a schematic sectional drawing of the acceleration sensor in Embodiment 2 of this invention, Comprising: The cross-sectional position respond | corresponds to the cross section which follows the IV-IV line of FIG. It is the schematic which shows arrangement | positioning with the fixed electrode part and movable electrode part of the acceleration sensor in Embodiment 2 of this invention. It is a schematic sectional drawing which shows the relative positional relationship of the fixed electrode part and movable electrode part of the acceleration sensor in Embodiment 2 of this invention, Comprising: The sum total of the opposing area of a movable electrode part and a fixed electrode part changes The movable electrode is moved in the direction of the substrate (A), the movable electrode portion is moved in the direction of the substrate within a certain range of the total area of the movable electrode portion and the fixed electrode portion (B), the movable electrode portion is A state in which the movable electrode portion does not move (C), a state in which the movable electrode portion moves in the direction opposite to the substrate within a certain range of the total facing area of the movable electrode portion and the fixed electrode portion (D), It is a schematic sectional drawing which shows the state (E) which the movable electrode moved to the opposite direction to the board | substrate until the sum total of the opposing area changed. It is a schematic plan view of the acceleration sensor in Embodiment 3 of this invention. It is a schematic sectional drawing which follows the XXXIV-XXXIV line | wire of FIG. It is a schematic sectional drawing which follows the XXXV-XXXV line | wire of FIG. It is a schematic sectional drawing which shows the state by which the acceleration was applied to the acceleration sensor in Embodiment 3 of this invention, Comprising: The cross-sectional position respond | corresponds to FIG. It is a schematic sectional drawing of the acceleration sensor in Embodiment 3 of this invention, Comprising: It is a schematic sectional drawing which shows the structure by which the detection electrode is arrange | positioned on either side across the twist axis, The cross-sectional position respond | corresponds to FIG. It is a schematic plan view of the acceleration sensor in Embodiment 4 of this invention. FIG. 39 is a schematic cross-sectional view taken along line XXXIX-XXXIX in FIG. 38. It is a schematic sectional drawing which follows the XL-XL line | wire of FIG. It is a schematic sectional drawing which shows the state in which the acceleration was applied to the acceleration sensor in Embodiment 4 of this invention, Comprising: The cross-sectional position respond | corresponds to FIG. It is a schematic sectional drawing which shows the relative positional relationship of the stationary electrode and movable electrode of the acceleration sensor in Embodiment 4 of this invention, Comprising: When a detection frame part rotates, one side and the other side of a detection frame part FIG. 6 is a schematic cross-sectional view showing the state in which the movable electrode is moved up and down, and the state in which the movable electrode is moved until the opposing area of the movable electrode and the fixed electrode is changed by the rotational movement of the detection frame portion to one side (A ), A state in which the movable electrode moves within a certain range of the opposed area between the movable electrode and the fixed electrode due to the rotational movement of the detection frame portion to one side (B), a state in which the movable electrode does not move (C), a detection frame When the movable electrode is moved within a certain range of the area where the movable electrode and the fixed electrode face each other by rotating the part to the other side (D), it is possible by rotating the detection frame part to the other side. To the opposite area of the electrode and the fixed electrode changes is a schematic sectional view showing a state in which the movable electrode is moved (E). It is a schematic sectional drawing of the acceleration sensor in Embodiment 4 of this invention, Comprising: It is a schematic sectional drawing which shows the structure by which the detection electrode is arrange | positioned on either side across the twist axis, The sectional position respond | corresponds to FIG. It is a schematic plan view of the acceleration sensor in Embodiment 5 of this invention. It is a schematic sectional drawing in alignment with the XLV-XLV line | wire of FIG. FIG. 45 is a schematic sectional view taken along line XLVI-XLVI in FIG. 44. FIG. 46 is a schematic cross-sectional view showing a state where the inertial mass body of the acceleration sensor according to Embodiment 5 of the present invention is moved by the voltage application electrode, and the cross-sectional position thereof corresponds to FIG. 45. It is a schematic sectional drawing of the acceleration sensor in Embodiment 6 of this invention, Comprising: The cross-sectional position respond | corresponds to the cross section which follows the XL-XL line | wire of FIG. It is a schematic sectional drawing which shows the relative positional relationship of the fixed electrode part of the acceleration sensor in Embodiment 6 of this invention, and a movable electrode part, Comprising: When a detection frame part rotates, one side of a detection frame part and It is a schematic sectional view which shows the state where the movable electrode part of the other side moved up and down, and the movable electrode until the opposed area of the movable electrode part and the fixed electrode part changes greatly by the rotational movement of the detection frame part to one side The movable electrode portion is moved (A), the movable electrode portion is moved until the opposing area of the movable electrode portion and the fixed electrode portion is changed by rotating the detection frame portion to one side (B), the movable electrode The state in which the movable electrode part does not move (C), the state in which the movable electrode part has moved until the opposing area between the movable electrode part and the fixed electrode part is changed by the rotational movement of the detection frame part to the other side (D), detection Frame part is a schematic sectional view showing a state in which the movable electrode portion is moved to the opposing area between the fixed electrode portion movable electrode portion is greatly changed (E) by rotating movement to the other side.

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

  In FIG. 1 and FIG. 2, a detection axis DA perpendicular to the paper surface is introduced for convenience of explanation. The direction of the detection axis DA coincides with the direction of acceleration targeted by the acceleration sensor of the present embodiment. The same applies to the drawings corresponding to FIGS. 1 and 2 below.

  Referring to FIG. 1, acceleration sensor 100 of the present embodiment includes substrate 1, fixed member 2, displacement member 3, anchor member 5, fixed electrode 6, detection electrode 8, and insulator 9. It has mainly.

  1 to 4, a fixing member 2 and an anchor member 5 are supported on the substrate 1. An insulator 9 is interposed between the substrate 1, the fixing member 2 and the anchor member 5.

  The displacement member 3 is supported on the surface of the substrate 1 so as to be displaceable in the thickness direction of the substrate 1 with respect to the substrate 1. The displacement member 3 includes a beam member 4, a movable electrode 7, and an inertia mass body 31. The displacement member 3 is supported by the anchor member 5 by the beam member 4. The beam member 4 is supported on the surface of the substrate 1 via the anchor member 5. The beam member 4 has a plurality of spring members. The anchor member 5 and the inertial mass body 31 are connected to one end and the other end of the inertial mass body 31 in one direction in plan view by a plurality of spring members of the beam member 4, respectively.

  In addition, the number of the spring members of the beam member 4 that connects the one end portion and the other end portion of the inertia mass body 31 in one direction and the anchor member 5 in a plan view is not limited to a plurality, and may be a single number. . Moreover, the arrangement position and shape of the beam member 4 should just be comprised so that the inertia mass body 31 can be moved to the thickness direction of the board | substrate 1. FIG.

  The inertia mass body 31 is supported by the beam member 4 so as to be displaceable in the thickness direction of the substrate 1 with respect to the substrate 1. The inertia mass body 31 has a movable electrode 7. The plurality of movable electrodes 7 are respectively provided at one end and the other end of the inertial mass body 31 in the other direction where the plurality of movable electrodes 7 intersect the one direction in plan view. The plurality of movable electrodes 7 may be arranged in a comb shape in plan view.

  The fixing member 2 is disposed outside the inertia mass body 31 in plan view. The fixed member 2 is provided with a plurality of fixed electrodes 6. The plurality of fixed electrodes 6 may be arranged in a comb shape in a plan view. The fixed electrode 6 is disposed so as to face the movable electrode 7. The fixed electrode 6 is configured to generate an electrostatic force between the fixed electrode 6 and the movable electrode 7. The fixed electrode 6 and the movable electrode 7 may be arranged so that their comb teeth shapes are combined. The fixed electrode 6 and the movable electrode 7 may be arranged close to each other at equal intervals. The movable electrode 7 and the fixed electrode 6 may be arranged to face each other in the direction along the surface of the substrate 1.

  The fixed electrode 6 and the movable electrode 7 are regions in which the facing area between the movable electrode 7 and the fixed electrode 6 is constant and the acceleration is large even when the displacement member 3 is displaced in the thickness direction of the substrate 1 in a region where the acceleration is small. When the displacement member 3 is displaced in the thickness direction of the substrate 1, the facing area between the movable electrode 7 and the fixed electrode 6 is changed. As shown in FIG. 2, the facing area is an area where the fixed electrode 6 and the movable electrode 7 overlap each other in a cross-sectional view.

  The dimension Hm of the movable electrode 7 in the thickness direction of the substrate 1 is different from the dimension Hb of the fixed electrode 6 in the thickness direction of the substrate 1. The dimension Hb of the fixed electrode 6 in the thickness direction of the substrate 1 may be larger than the dimension Hm of the movable electrode 7 in the thickness direction of the substrate 1. The difference between the dimension Hm of the movable electrode 7 in the thickness direction of the substrate 1 and the dimension Hb of the fixed electrode 6 in the thickness direction of the substrate 1 is ΔH. Therefore, ΔH = (Hb−Hm). The fixed electrode 6 and the movable electrode 7 include a height difference between an end surface of the fixed electrode 6 on the substrate 1 side and an end surface of the movable electrode 7 on the substrate 1 side, and an end surface of the fixed electrode 6 opposite to the substrate 1 and the movable electrode 7. It is preferable that the height difference from the opposite end surface of the substrate 1 is ΔH / 2.

  The detection electrode 8 is formed on the surface of the substrate 1 so as to face the displacement member 3. An insulator 9 is interposed between the substrate 1 and the detection electrode 8. The detection electrode 8 constitutes the displacement member 3 and the capacitance Cd. The displacement member 3 and the detection electrode 8 are configured such that the capacitance Cd changes as the displacement member 3 moves. The acceleration sensor 100 is configured to detect acceleration based on the change in the capacitance Cd.

  The difference in height between the end surface of the fixed electrode 6 on the substrate 1 side and the end surface of the movable electrode 7 on the substrate 1 side, the end surface of the fixed electrode 6 on the opposite side of the substrate 1 and the opposite side of the movable electrode 7 on the substrate 1 side. The difference in height with respect to the end face may be different because a difference in displacement differential of the capacitance Ci only has to be generated. Further, by making the magnitude of the acceleration at which the change rate of the detection signal with respect to the applied acceleration changes the same in both directions of the applied acceleration, the applied acceleration is accurately detected in both directions. Therefore, the height difference between the end surface of the fixed electrode 6 on the substrate 1 side and the end surface of the movable electrode 7 on the substrate 1 side, the end surface of the fixed electrode 6 opposite to the substrate 1, and the opposite side of the movable electrode 7 on the substrate 1. It is preferable to make the difference in height from the end face of the same.

  As the substrate 1, a silicon substrate can be used. Further, as the fixed member 2, the beam member 4, the anchor member 5, the fixed electrode 6, the movable electrode 7, the detection electrode 8, and the inertia mass body 31, a conductive polysilicon (polycrystalline silicon) film can be used. This conductive polysilicon film preferably has low stress and no stress distribution. As the insulator 9, a silicon nitride film or a silicon oxide film can be used.

  The acceleration sensor 100 is applied to an external IC or the like for applying a voltage to the fixed member 2 and the anchor member 5 and converting a signal into a voltage of the electrostatic capacitance Cd between the displacement member 3 and the detection electrode 8. And are electrically connected. The acceleration sensor 100 and the external IC can be connected by a bonding wire (not shown) connected to the fixing member 2, the anchor member 5 and the detection electrode 8, a wiring pattern (not shown) on the substrate 1, or the like.

  With reference to FIG. 5 and FIG. 6, the electrical connection between the structural members of the acceleration sensor of the present embodiment will be described. The fixed member 2 and the fixed electrode 6 are electrically connected so as to be equipotential. The beam member 4, the anchor member 5, the movable electrode 7, and the inertia mass body 31 are electrically connected so as to be equipotential. The substrate 1 and the detection electrode 8 are not electrically connected to any of the above constituent members.

Next, a method for manufacturing the acceleration sensor according to the present embodiment will be described.
The structure of the acceleration sensor 100 of the present embodiment described above can be manufactured by, for example, a so-called semiconductor microfabrication technology or MEMS device technology in which processes such as film formation, patterning, etching, and planarization are repeatedly performed on a silicon substrate. A structure in which the height of the fixed electrode 6 and the height of the movable electrode 7 are different can be manufactured by three stages of film formation, patterning, and etching.

  7 to 17, the cross-sectional position in (A) corresponds to the cross-sectional position in FIG. 2, the cross-sectional position in (B) corresponds to the cross-sectional position in FIG. 3, and the cross-sectional position in (C). Corresponds to the cross-sectional position of FIG.

  With reference to FIGS. 7A to 7C, an insulating film 101 is formed on the substrate 1 by LPCVD (Low Pressure Chemical Vapor Deposition). For example, a silicon substrate is suitable as the substrate 1. As the insulating film 101, for example, a silicon nitride film or a silicon oxide film is suitable. This insulating film 101 corresponds to the insulator 9 shown in FIGS.

  With reference to FIGS. 8A to 8C, a conductive polysilicon film 102 is formed on the insulating film 101. The formed conductive polysilicon film 102 is selectively removed. The selectively removed conductive polysilicon film 102 corresponds to the detection electrode 8 shown in FIGS.

  Referring to FIGS. 9A to 9C, a PSG (Phosphosilicate Glass) film 103 is formed. Referring to FIGS. 10A to 10C, PSG film 103 is patterned and etched. The etched PSG film 103 corresponds to the space between the inertial mass body 31 and the detection electrode 8 shown in FIGS.

  Referring to FIGS. 11A to 11C, a conductive polysilicon film 102 is formed. Referring to FIGS. 12A to 12C, the conductive polysilicon film 102 is planarized by CMP (Chemical Mechanical Polishing) processing. A part of the planarized conductive polysilicon film 102 corresponds to the beam member 4 shown in FIGS.

  Referring to FIGS. 13A to 13C, conductive polysilicon film 102 is patterned and etched. Referring to FIGS. 14A to 14C, a PSG film 103 is formed. Thereafter, the PSG film 13 is planarized by etching.

  Referring to FIGS. 15A to 15C, a conductive polysilicon film 102 is formed. Thereafter, the conductive polysilicon film 102 is patterned and etched. The etched conductive polysilicon film 102 corresponds to the movable electrode 7 shown in FIGS. Subsequently, a PSG film 103 is formed. Thereafter, the PSG film is planarized by etching.

  With reference to FIGS. 16A to 16C, a conductive polysilicon film 102 is formed. Thereafter, the conductive polysilicon film 102 is patterned and etched. The etched conductive polysilicon film 102 corresponds to the fixing member 2, the inertia mass body 31, the anchor member 5, and the fixed electrode 6 shown in FIGS. 2 to 4. Subsequently, a PSG film 103 is formed. Thereafter, the PSG film is planarized by etching.

  Referring to FIGS. 17A to 17C, the PSG film 103 is removed by etching. Thereby, the acceleration sensor 100 of this Embodiment shown by FIGS. 2-4 is manufactured.

Next, the operation of the acceleration sensor according to the present embodiment will be described.
In the acceleration sensor of the present embodiment, for example, when a constant DC voltage is applied between the fixed member 2 and the anchor member 5, the applied acceleration is large, that is, the displacement of the displacement member 3 is large. A restoring force resulting from an electrostatic force due to a potential difference between the fixed electrode 6 and the movable electrode 7 is obtained. Thereby, the detection range of the applied acceleration can be expanded by increasing the restoring force of the beam member 4 equivalently, that is, increasing the rigidity. Details will be described below.

  First, an operation in which acceleration is detected by the displacement member 3 and the detection electrode 8 will be described. Referring to FIG. 18, when acceleration AZ in the direction of detection axis DA is applied to acceleration sensor 100 of the present embodiment, beam member 4 is deformed, and the force and beam acting on inertial mass body 31 due to acceleration AZ. The inertia mass body 31 is displaced to a position where the restoring force of the spring member of the member 4 is balanced.

  In general, since the restoring force and displacement of the spring member are proportional to each other, the displacement of the inertial mass body 31 is proportional to the applied acceleration AZ. The displacement of the inertial mass body 31 is detected as a change in the capacitance Cd generated between the inertial mass body 31 and the detection electrode 8 due to a change in the distance between the inertial mass body 31 and the detection electrode 8. The applied acceleration AZ is detected from the change in the capacitance Cd.

  Next, an operation in which the electrostatic force due to the potential difference between the fixed electrode 6 and the movable electrode 7 affects the displacement of the displacement member 3 will be described.

  Referring to FIG. 19, a movable electrode 7 having a dimension Hm is sandwiched between two fixed electrodes 6 having a dimension Hb. The dimension Hb of the two fixed electrodes 6 is larger than the dimension Hm of the movable electrode 7. The fixed electrode 6 and the movable electrode 7 are arranged at a certain distance GA.

  Since the fixed electrode 6 is connected to the substrate 1 through the fixing member 2 as shown in FIG. 1, the position is fixed. Since the movable electrode 7 is connected to the anchor member 5 via the inertia mass body 31 and the beam member 4 as shown in FIG. 1, it can be displaced in the thickness direction of the substrate 1 (detection axis DA direction). Further, for example, a constant DC voltage is applied between the fixed member 2 and the anchor member 5, thereby generating a potential difference between the two fixed electrodes 6 and the movable electrode 7.

  Referring to FIGS. 20A to 20E, the capacitance Ci generally generated between the fixed electrode 6 and the movable electrode 7 is (opposing area / distance) when considered in a typical parallel plate model. Proportional. Since the distance GA between the fixed electrode 6 and the movable electrode 7 is constant, the capacitance Ci is proportional to the facing area between the fixed electrode 6 and the movable electrode 7. The fixed electrode 6 and the movable electrode 7 are configured to have the same length. For this reason, the opposing area of the fixed electrode 6 and the movable electrode 7 is proportional to the dimension Hm of the movable electrode 7 in the thickness direction of the substrate 1.

  Therefore, as shown in FIGS. 20B to 20D, when the displacement Z of the movable electrode 7 is in a range of −ΔH / 2 ≦ Z ≦ + ΔH / 2 (a region where acceleration is small), even if the movable electrode 7 is displaced. Since the opposed area of the fixed electrode 6 and the movable electrode 7 is constant and does not change, the capacitance Ci with respect to the displacement Z of the movable electrode 7 does not change. The displacement Z is negative on the lower side and positive on the upper side from the center line in the figure.

  As shown in FIGS. 20A and 20E, in a region where the absolute value of the displacement Z of the movable electrode 7 exceeds ΔH / 2 (a region where acceleration is large), if the movable electrode 7 is displaced, the fixed electrode 6 and the movable electrode 7 are displaced. The capacitance Ci changes. In general, in a system in which the capacitance Ci changes with displacement, the electrostatic force proportional to the change of the capacitance Ci with respect to the displacement, that is, the displacement differential (∂Ci / ∂Z) of the capacitance Ci and the square of the potential difference. Fele is generated. The generated electrostatic force Fele has only a component in the substrate thickness direction due to the symmetry of the flat plate arrangement.

  As shown in FIG. 20A, in the region where the displacement Z is Z <−ΔH / 2, (＜ Ci / ∂Z)> 0. As shown in FIGS. 20B to 20D, (∂Ci / ∂Z) = 0 in the region where the displacement Z is −ΔH / 2 ≦ Z ≦ + ΔH / 2. As shown in FIG. 20E, the capacitance displacement differential (微分 Ci / ＺZ) <0 in the region where the displacement Z is Z> + ΔH / 2. Therefore, as shown in FIGS. 20A and 20E, in the region where the absolute value of the displacement Z exceeds ΔH / 2, an electrostatic force is generated in the direction of decreasing the absolute value of the displacement Z of the movable electrode 7.

  Referring to FIG. 21, when a typical parallel plate model is considered, the capacitance Ci with respect to the displacement Z of the movable electrode 7 decreases in the region where the absolute value of the displacement Z exceeds ΔH / 2, and the displacement Z It shows a tendency to be constant in the range of −ΔH / 2 ≦ Z ≦ + ΔH / 2.

  Referring to FIG. 22, when considered with a typical parallel plate model, the capacitance displacement derivative (∂Ci / ∂Z) and the resulting electrostatic force Fele with respect to the displacement Z of the movable electrode 7 are the absolute values of the displacement Z. In the region where ΔH / 2 exceeds ΔH / 2, the capacitance displacement derivative (変 位 Ci / ∂Z) and the absolute value of the generated electrostatic force Fele increase, and in the region where the displacement Z is −ΔH / 2 ≦ Z ≦ + ΔH / 2. It shows a tendency to be constant.

  In general, in a flat plate having an actual finite height, the capacitance Ci generated between the two flat plates changes gradually with respect to the displacement due to the influence of the electric field distribution at the end of the flat plate. Therefore, the displacement differential (∂Ci / ∂Z) of the electrostatic capacitance and the generated electrostatic force Fele continuously change when the displacement Z is in the vicinity of -ΔH / 2 and + ΔH / 2. Thereby, in the region where the absolute value of the displacement Z is large, the absolute value of the electrostatic force Fele gradually increases.

  Referring to FIG. 23, when the influence of the electric field distribution at the end of the flat plate is taken into consideration, the capacitance Ci with respect to the displacement Z of the movable electrode 7 is in the region where the absolute value of the displacement Z exceeds ΔH / 2. The gradient gradually increases and decreases due to the influence of the electric field distribution of the portion, and the displacement Z tends to be constant in the range of −ΔH / 2 ≦ Z ≦ + ΔH / 2.

  Referring to FIG. 24, when the influence of the electric field distribution at the end of the flat plate is considered, the displacement differential (∂Ci / ∂Z) of the capacitance with respect to the displacement Z of the movable electrode 7 and the generated electrostatic force Fele are expressed as follows. In the region where the absolute value of ΔH / 2 exceeds ΔH / 2, the displacement derivative of capacitance (ｉCi / ∂Z) and the absolute value of the generated electrostatic force Fele gradually increase, and the displacement Z becomes −ΔH / 2 ≦ Z ≦ + ΔH. It shows a tendency to be constant in the region of / 2.

  The generated electrostatic force Fele is generated in accordance with the displacement differential (変 位 Ci / ∂Z) of the capacitance, that is, the change in the capacitance Ci. As shown in FIG. 23, the electrostatic capacity Ci decreases in a region where the absolute value of the displacement Z is larger than ΔH / 2 due to the influence of the electric field distribution at the end of the electrode. In the displacement differential (Ci / ∂Z), the absolute value of the displacement Z gradually increases in a region where the absolute value of the displacement Z is larger than ΔH / 2. Since the electrostatic force Fele is proportional to the change in the capacitance Ci, the absolute value of the electrostatic force Fele gradually increases in a region where the absolute value of the displacement Z is larger than ΔH / 2.

  As described above, in the region where the absolute value of the displacement Z of the displacement member 3 exceeds ΔH / 2, the absolute value of the electrostatic force Fele due to the potential difference between the fixed electrode 6 and the movable electrode 7 gradually increases. To do. Thereby, the restoring force resulting from electrostatic force Fele increases.

  Referring to FIG. 25, in a region where the absolute value of displacement Z of displacement member 3 exceeds ΔH / 2, that is, a region where displacement of displacement member 3 due to applied acceleration G is large, the restoring force caused by electrostatic force Fele is a beam member. 4 is added to the restoring force by the spring member. As a result, the restoring force of the beam member 4 is equivalently increased, that is, the rigidity is increased. Therefore, in a region where the displacement of the displacement member 3 is large, the displacement Z of the displacement member 3 is −ΔH / 2 ≦ Z ≦ + ΔH / 2. Compared to a region, that is, a region where the displacement of the displacement member 3 due to the applied acceleration G is small, the change rate of the displacement of the displacement member 3 is small.

  Therefore, in the acceleration sensor 100 of the present embodiment, for example, in a region where the displacement of the displacement member 3 due to the applied acceleration G is large compared to a case where a constant DC voltage is not applied between the fixed electrode 6 and the movable electrode 7. A larger acceleration can be applied until the displacement member 3 reaches the same displacement (Zmax in FIG. 25).

  That is, as shown in FIG. 25, the applied acceleration G in the case of the displacement Zmax is compared with the applied acceleration Gmax in the case where a constant DC voltage is not applied between the fixed electrode 6 and the movable electrode 7. In the acceleration sensor 100, the applied acceleration Gmax new, which is larger than the applied acceleration Gmax, is obtained. Therefore, in the acceleration sensor 100 of the present embodiment, a wide range of acceleration can be detected by the electrostatic force Fele acting on the movable electrode 7 of the displacement member 3 in a region where the applied acceleration G is large.

  Since the electrostatic force Fele is proportional to the square of the potential difference between the fixed electrode 6 and the movable electrode 7 as described above, it can be detected by, for example, a voltage applied between the fixed member 2 and the anchor member 5. The range of acceleration can be changed. That is, the acceleration detection range can be increased by increasing the applied voltage.

  In addition, a constant DC voltage is applied between the fixed member 2 and the anchor member 5, but it is sufficient that a potential difference is applied between the fixed electrode 6 and the movable electrode 7. An AC voltage may be applied between the first and second terminals. In this case, it is desirable that the frequency of the applied AC voltage be higher than the mechanical resonance frequency of the acceleration sensor 100 of the present embodiment in order to prevent damage due to resonance.

Next, the function and effect of the acceleration sensor according to the present embodiment will be described.
According to the acceleration sensor 100 of the present embodiment, in a region where the acceleration is small, even if the displacement member 3 is displaced in the thickness direction of the substrate 1, the facing area between the movable electrode 7 and the fixed electrode 6 is constant, and the acceleration When the displacement member 3 is displaced in the thickness direction of the substrate 1 in a large area, the facing area of the movable electrode 7 and the fixed electrode 6 changes. For this reason, the electrostatic force Fele generated according to the change of the electrostatic capacity Ci due to the change of the facing area between the movable electrode 7 and the fixed electrode 6 can be made constant in a region where the acceleration is small, and can be increased in a region where the acceleration is large. .

  Thereby, since the restoring force of the beam member 4 is equivalently increased in a region where acceleration is large, the displacement of the displacement member 3 due to application of acceleration is larger in the region than in the region where the displacement of the displacement member 3 is small. The change rate of the displacement of the member 3 becomes small. Therefore, a wide range of accelerations can be detected.

  Further, in the region where the displacement of the displacement member 3 due to the application of acceleration is large due to the electrostatic force Fele generated according to the change of the electrostatic capacity Ci due to the change of the facing area between the fixed electrode 6 and the movable electrode 7, the acceleration sensor 100 It can suppress that a structural member contacts mutually. Thereby, the malfunction and performance defect resulting from the failure | damage and adsorption | suction of a structural member by the contact of a structural member can be suppressed.

  Further, it is preferable that the height difference between the upper surface and the lower surface in the thickness direction of the substrate 1 between the fixed electrode 6 and the movable electrode 7 is equal. Thereby, the acceleration in both directions of the acceleration detection direction can be accurately detected.

  According to the acceleration sensor 100 of the present embodiment, the dimension of the movable electrode 7 in the thickness direction of the substrate 1 may be different from the dimension of the fixed electrode 6 in the thickness direction of the substrate 1. Therefore, in a region where the displacement of the displacement member 3 due to application of acceleration is large, the movable electrode 7 is based on the difference between the dimension Hm of the movable electrode 7 in the thickness direction of the substrate 1 and the dimension Hb of the fixed electrode 6 in the thickness direction of the substrate 1. In the case of a large movement, the electrostatic force Fele generated according to the change in the capacitance Ci due to the change in the facing area between the fixed electrode 6 and the movable electrode 7 increases.

  Therefore, by reducing the rate of change of the displacement of the displacement member 3 in a region where the acceleration is large, it is possible to detect a wide range of accelerations without contacting the constituent members in a region where the applied acceleration is large.

  According to the acceleration sensor 100 of the present embodiment, the movable electrode 7 and the fixed electrode 6 may be arranged to face each other in the direction along the surface of the substrate 1. For this reason, when acceleration is applied in the thickness direction of the substrate 1, the movable electrode 7 and the fixed electrode 6 are disposed so as to face each other in a direction crossing the direction in which the acceleration is applied. Thereby, it is suppressed that the movable electrode 7 contacts the fixed electrode 6 even in the region where the applied acceleration is large.

  The acceleration sensor 100 according to the present embodiment further includes the detection electrode 8 that is disposed on the surface of the substrate 1 so as to face the displacement member 3 and constitutes a capacitance with the displacement member. For this reason, when acceleration is applied in the thickness direction of the substrate 1, the detection electrode 8 configures the displacement member 3 and the capacitance Cd in the acceleration detection direction. Thereby, acceleration can be detected more accurately.

  As a first modification of the present embodiment, the beam member 4 may be disposed at one end of the inertia mass body 31 as a cantilever.

  Referring to FIG. 26, the beam member 4 is disposed at one end of the inertial mass body 31 as a cantilever beam. Thereby, compared with the case where the beam member 4 is arrange | positioned at the one end part and other end part of the inertial mass body 31, the size of the acceleration sensor 100 can be made small. In addition, productivity including manufacturing cost can be improved.

  As a second modification of the present embodiment, the dimension Hm of the movable electrode 7 in the thickness direction of the substrate 1 may be larger than the dimension Hb of the fixed electrode 6 in the thickness direction of the substrate 1.

  Referring to FIG. 27, the dimension Hm of movable substrate 7 in the thickness direction of substrate 1 is larger than dimension Hb of fixed electrode 6 in the thickness direction of substrate 1. In the above description, the case where the dimension Hb of the fixed electrode 6 in the thickness direction of the substrate 1 is larger than the dimension Hm of the movable electrode 7 in the thickness direction of the substrate 1 is described. Even if the electrode 6 is larger than the dimension Hb of the substrate 1 in the thickness direction, it is possible to detect a wide range of acceleration without contacting the constituent members in a region where the applied acceleration is large as described above.

  Further, as a third modification of the present embodiment, the fixed electrode 6 and the movable member 7 are not configured in a comb-teeth shape, and the fixed member 2 and the displacement member 3 are brought close to each other, whereby the fixed member 2 and the displacement member 3 are arranged. 3 may have the functions of the fixed electrode 6 and the movable electrode 7 together.

  Referring to FIGS. 28 and 29, inertial mass body 31 is formed up to the vicinity of the inside of fixing member 2 in one direction in plan view. Thereby, the fixing member 2 and the inertial mass body 31 are brought close to each other. Capacitance Ci is constituted by a proximity portion between the fixing member 2 and the inertial mass body 31. Unlike the above, the fixing member 2 and the inertia mass body 31 are not provided independently.

  In the above description, the acceleration sensor 100 increases the opposing area by making the fixed electrode 6 and the movable electrode 7 comb-shaped, and the displacement differential (∂) in the region where the displacement of the displacement member 3 is large. The absolute value of the electrostatic force generated by increasing Ci / ∂Z) is increased efficiently. However, the facing area between the electrodes that generate the electrostatic force Fele does not change in the region where the displacement of the displacement member 3 is small, and the facing area between the electrodes that generate the electrostatic force Fele changes in the region where the displacement of the displacement member 3 is large. do it.

  Accordingly, by providing the fixed member 2 with the function of the fixed electrode 6 and also having the function of the movable electrode 7 with the displacement member 3, the displacement member 3 is changed by the change in the facing area between the fixed member 2 and the displacement member 3. The electrostatic force Fele can be increased in a region where the displacement of is large. Therefore, a wide range of acceleration can be detected in the same manner as described above.

(Embodiment 2)
The acceleration sensor according to the second embodiment of the present invention is mainly different from the acceleration sensor according to the first embodiment in the configuration of the movable electrode and the fixed electrode.

  Referring to FIG. 30, in the acceleration sensor 100 of the present embodiment, the movable electrode 7 has a plurality of movable electrode portions 71 separated from each other. The fixed electrode 6 has a plurality of fixed electrode portions 61 separated from each other. The plurality of movable electrode portions 71 and the plurality of fixed electrode portions 61 have a plurality of sets P of the movable electrode portions 71 and the fixed electrode portions 61 disposed so as to face each other.

  The set P may be composed of two fixed electrode portions 61 and one movable electrode portion 71 as shown in FIG. 30, and is composed of one fixed electrode portion 61 and one movable electrode portion 71. It may be.

  The fixed electrode portion 61 and the movable electrode portion 71 in the set P are configured to have different heights from the surface of the substrate 1. The fixed electrode portion 61 and the movable electrode portion 71 in the set P are high with respect to the substrate 1 between the end surface of the fixed electrode portion 61 opposite to the substrate 1 and the end surface of the movable electrode portion 71 opposite to the substrate 1. A difference ΔP is generated. The fixed electrode portion 61 and the movable electrode portion 71 in the set P also have a height difference ΔP between the end surface of the fixed electrode portion 61 on the substrate 1 side and the end surface of the movable electrode portion 71 on the substrate 1 side. It is configured to occur.

  The height of the fixed electrode portion 61 and the movable electrode portion 71 of the set P adjacent to each other from the surface of the substrate 1 is such that the height of the fixed electrode portion 61 of one set P is the height of the movable electrode portion 71 of the other set P. The height of the movable electrode portion 71 of one set P may be the same as the height of the fixed electrode portion 61 of one set P.

  The plurality of movable electrode portions 71 and the plurality of fixed electrode portions 61 have a plurality of sets P of movable electrode portions 71 and fixed electrode portions 61 in a region where acceleration is small even if the displacement member 3 is displaced in the thickness direction of the substrate 1. When the displacement member 3 is displaced in the thickness direction of the substrate 1 in a region where the total acceleration area is constant and acceleration is large, the total area where the movable electrode portions 71 and the fixed electrode portions 61 of the plurality of sets P face each other. Is configured to change.

  Referring to FIG. 31, in a plurality of sets P, a movable electrode portion 71 having a dimension Hm is sandwiched between two fixed electrode portions 61 having a dimension Hb. Hereinafter, two sets P will be described as an example, but a plurality of sets P may be used. The dimension Hb in the thickness direction of the substrate 1 of the plurality of fixed electrode portions 61 and the dimension Hm in the thickness direction of the substrate 1 of the plurality of movable electrode portions 71 are configured to be the same size.

  In the set P, the movable electrode portion 71 is disposed so that the movable electrode portion 71 protrudes toward the substrate 1 with respect to the fixed electrode portion 61, and the movable electrode portion 71 is disposed on the substrate 1 with respect to the fixed electrode portion 61. And a set P (convex portion) arranged so as to protrude toward the opposite side. The first set P <b> 1 is configured such that the movable electrode portion 71 is positioned below the fixed electrode portion 61 with respect to the substrate 1. The second set P <b> 2 is configured such that the movable electrode portion 71 is positioned above the fixed electrode portion 61 with respect to the substrate 1.

  In addition, since the structure of this embodiment other than this is the same as that of Embodiment 1 mentioned above, the same code | symbol is attached | subjected about the same element and the description is not repeated. In addition, since the present embodiment can be manufactured by the same manufacturing method as that of the first embodiment, the description thereof will not be repeated.

  Next, an operation in which the electrostatic force due to the potential difference between the fixed electrode portion 61 and the movable electrode portion 71 affects the displacement of the displacement member 3 will be described.

  As shown in FIG. 31, a length in which one fixed electrode portion 61 and one movable electrode portion 71 are opposed to each other is defined as a facing length Hx. In one set, since one P movable electrode portion 71 is sandwiched between two fixed electrode portions 61, the opposing length of the fixed electrode portion 61 and the movable electrode portion 71 in one set P is 2Hx. In addition, the length of the fixed electrode part 61 and the movable electrode part 71 is comprised by the equal length. For this reason, the opposing area of the fixed electrode part 61 and the movable electrode part 71 is proportional to 2Hx.

  Referring to FIGS. 32 (B) to (D), in the plurality of sets P, the movable electrode portion 71 has a displacement Z of −ΔP ≦ Z ≦ + ΔP (region where acceleration is small). A set PL in which the facing area between the movable electrode portion 71 and the fixed electrode portion 61 is increased by displacement in the thickness direction of the substrate 1 and a set PS in which the facing area between the movable electrode portion 71 and the fixed electrode portion 61 is reduced. Have.

  When the displacement Z of the movable electrode portion 71 is in the range of −ΔP ≦ Z ≦ + ΔP (the region where acceleration is small), the fixed electrode is not used in the set PS even if the opposing area between the fixed electrode portion 61 and the movable electrode portion 71 is increased in the set PL. The facing area between the portion 61 and the movable electrode portion 71 is reduced. For this reason, when the displacement Z of the movable electrode portion 71 is in the range of −ΔP ≦ Z ≦ + ΔP (the region where the acceleration is small), the fixed electrode portion 61 in the set P including the set PL and the set PS even if the movable electrode portion 71 is displaced. And the total facing area of the movable electrode portion 71 is constant and does not change. Therefore, the capacitance Ci with respect to the displacement Z of the movable electrode 7 does not change.

  32A and 32E, in a region where the absolute value of displacement Z of movable electrode portion 71 exceeds ΔP (a region where acceleration is large), when movable electrode portion 71 is displaced, a plurality of sets P are obtained. Since the sum of the opposing areas of the movable electrode portion 71 and the fixed electrode portion 61 changes, the capacitance Ci changes. For this reason, an electrostatic force Fele proportional to the displacement differential (∂Ci / ∂Z) of the capacitance Ci and the square of the potential difference is generated.

Next, the function and effect of the acceleration sensor according to the present embodiment will be described.
According to the acceleration sensor 100 of the present embodiment, the plurality of movable electrode portions 71 and the plurality of fixed electrode portions 61 include a plurality of sets P of movable electrode portions 71 and fixed electrode portions 61 arranged so as to face each other. I have one. In a region where the acceleration is small, even if the displacement member 3 is displaced in the thickness direction of the substrate 1, the total of the facing areas of the movable electrode portions 71 and the fixed electrode portions 61 of the plurality of sets P is constant, and the acceleration When the displacement member 3 is displaced in the thickness direction of the substrate 1 in a large area, the total of the opposing areas of the plurality of sets P of movable electrode portions 71 and fixed electrode portions 61 changes.

  For this reason, the electrostatic force Fele generated according to the change of the electrostatic capacitance Ci due to the change of the total facing area of the movable electrode portion 71 and the fixed electrode portion 61 of the plurality of sets P is made constant in a region where the acceleration is small, It can be increased in a region where acceleration is large. As a result, it is possible to detect a wide range of acceleration without contacting the constituent members in a region where the applied acceleration is large.

  According to the acceleration sensor 100 of the present embodiment, the plurality of sets P includes the movable electrode portion 71, the fixed electrode portion 61, and the movable electrode portion 71 that are displaced in the thickness direction of the substrate 1 in a region where acceleration is small. A set PL in which the opposed area of the movable electrode portion 71 and the fixed electrode portion 61 are reduced.

  For this reason, even if the movable electrode portion 71 is displaced in the thickness direction of the substrate 1 in a region where the acceleration is small, the electrostatic force due to the change in the total facing area of the movable electrode portions 71 and the fixed electrode portions 61 of the plurality of sets P The electrostatic force Fele generated according to the change of the capacitance Ci can be made constant in a region where the acceleration is small.

  According to the acceleration sensor 100 of the present embodiment, the movable electrode portion 71 and the fixed electrode portion 61 have the same dimension in the thickness direction of the substrate 1, and the plurality of sets P are movable electrode portions relative to the substrate 1. A first set P1 configured such that 71 is positioned below the fixed electrode portion 61 and a second set P2 configured such that the movable electrode portion 71 is positioned above the fixed electrode portion 61 with respect to the substrate 1. And have.

  For this reason, in the first set P1 and the second set P2, the acceleration causes the electrostatic force Fele generated according to the change in the capacitance Ci due to the change in the total facing area of the movable electrode portion 71 and the fixed electrode portion 61. It can be made constant in a small area and large in a large acceleration area.

  In the above description, the case where the first set P1 and the second set P2 have the same number has been described. However, the first set P1 and the second set P2 may have different numbers. When the number of the first set P1 and the second set P2 is different, the displacement Z of the movable electrode portion 71 is in the range of −ΔP ≦ Z ≦ + ΔP, and the capacitance Ci of the first set P1 is Since the change and the change in the capacitance Ci in the second set P2 are not equal, the electrostatic force Fele is generated. However, a remarkably large electrostatic force Fele occurs in the region where the absolute value of the displacement Z of the movable electrode portion 71 exceeds ΔP. Since the electrostatic force Fele can be significantly increased in a region where acceleration is large compared to a region where acceleration is small, a wide range of acceleration can be detected even if the number of the first group P1 and the second group P2 is different. it can.

(Embodiment 3)
The acceleration sensor according to the third embodiment of the present invention is mainly different from the acceleration sensor according to the first embodiment in the configuration of the displacement member.

  33 to 35, the displacement member 3 of the acceleration sensor 100 of the present embodiment includes the movable electrode 7, the inertia mass body 31, the detection frame portion 32, the torsion beam 33, and the link beam 34. Have.

  The torsion beam 33 is supported by the substrate 1 via the anchor member 5. The torsion beam 33 is configured to be twisted about the torsion axis T. The detection frame portion 32 is supported by the torsion beam 33 so as to be rotatable about the torsion axis T. The link beam 34 is supported by the detection frame portion 32 at a position on an imaginary line L that is shifted from the twist axis T in a plan view.

  The link beam 34 crosses the torsion axis T of the torsion beam 33 with the torsion axis T and moves parallel to the one end side of the detection frame unit 32 by an offset e at the position on the imaginary line L. It is connected with. That is, the absolute value of the offset e is a dimension between the twist axis T and the imaginary line L.

  The inertia mass body 31 is supported by the link beam 34 so as to be displaceable in the thickness direction of the substrate 1 with respect to the substrate 1. The inertia mass body 31 has a movable electrode 7. The displacement of the connection portion between the link beam 34 and the inertia mass body 31 and the displacement of the connection portion between the link beam 34 and the detection frame portion 32 are configured to be the same. A detection electrode 8 is formed on the substrate 1 facing the detection frame portion 32. As shown in FIG. 34, the detection electrode 8 is formed on one side with respect to the anchor member 5.

  In addition, since the structure of this embodiment other than this is the same as that of Embodiment 1 mentioned above, the same code | symbol is attached | subjected about the same element and the description is not repeated. In addition, since the present embodiment can be manufactured by the same manufacturing method as that of the first embodiment, the description thereof will not be repeated.

Next, the operation of the acceleration sensor according to the present embodiment will be described.
Referring to FIG. 36, when acceleration AZ in the detection axis DA direction is applied to acceleration sensor 100 of the present embodiment, torsion beam 33 is deformed, and displacement member 3 excluding torsion beam 33 is displaced by acceleration AZ. The inertial mass body 31 is displaced to a position where the working force and the restoring force of the torsion beam 33 are balanced. The inertial mass body 31 is displaced in the direction opposite to the direction of the acceleration AZ.

  Referring to FIGS. 34 and 36, link beam 34 connected to inertial mass body 31 is also integrated with inertial mass body 31 and displaced in the direction opposite to acceleration AZ. Due to the displacement of the link beam 34 with respect to the acceleration AZ, the detection frame unit 32 receives a force in the direction of the imaginary line L of the link beam 34 in the direction opposite to the acceleration AZ. Since this imaginary line L is at a position translated from the torsion axis T of the torsion beam 33 by an offset e, torque acts on the detection frame portion 32. As a result, the detection frame part 32 is rotationally displaced.

  That is, the detection frame portion 32 is rotationally displaced in the direction of arrow R in the figure so that the upper surface of the detection frame portion 32 faces one end side (left side in FIG. 36) of the acceleration sensor 100. Since the distance between the detection frame unit 32 and the detection electrode 8 is reduced by the rotational displacement of the detection frame unit 32, the capacitance Cd formed by the detection frame unit 32 and the detection electrode 8 increases. The acceleration AZ is detected from the change in the capacitance Cd.

  Note that the operation in which the electrostatic force due to the potential difference between the fixed electrode 6 and the movable electrode 7 affects the displacement of the displacement member 3 is the same as in the first embodiment described above, and therefore the description thereof will not be repeated.

  In the above description, the detection electrode 8 is formed on one side of the anchor member 5 as shown in FIG. 34, but the detection electrode 8 may be formed on both sides of the anchor member 5. Referring to FIG. 37, detection electrode 8L and detection electrode 8R are formed on substrate 1 facing detection frame portion 32 so as to sandwich anchor member 5 therebetween.

  Therefore, a change in capacitance is detected from the difference between the capacitance CdL constituted by the detection electrode 8L and the detection frame portion 32 and the capacitance CdR constituted by the detection electrode 8R and the detection frame portion 32. Can do. When the acceleration AZ in the direction of the detection axis DA is applied to the acceleration sensor 100, the detection frame portion 32 rotates around the torsion axis T of the torsion beam 33.

  For this reason, one of the electrostatic capacitance CdL and the electrostatic capacitance CdR becomes larger and the other becomes smaller. That is, since the changes in the capacitance CdL and the capacitance CdR have different signs, the sensitivity to the applied acceleration AZ can be increased.

  Further, the fixed electrode 6 and the movable electrode 7 of the present embodiment may adopt the configurations of the fixed electrode 6 and the movable electrode 7 of the second embodiment.

Next, the function and effect of the acceleration sensor according to the present embodiment will be described.
According to the acceleration sensor 100 of the present embodiment, the displacement member 3 is supported by the substrate 1 and twisted with the torsion beam 33 twisted about the torsion axis T, and the torsion beam 33 so as to be rotatable about the torsion axis T. A detection frame portion 32 supported by the detection frame portion 32, a link beam 34 supported by the detection frame portion 32 at a position on a virtual line L shifted from the twist axis T in plan view, and a thickness direction of the substrate 1 with respect to the substrate 1. And an inertial mass body 31 supported by the link beam 34 so as to be displaceable and having the movable electrode 7.

  Thereby, since the displacement of the inertial mass body 31 with respect to acceleration can be increased, the displacement of the movable electrode 7 can be increased. Therefore, a wide range of accelerations can be detected.

(Embodiment 4)
The acceleration sensor according to the fourth embodiment of the present invention is mainly different from the acceleration sensor according to the first embodiment in the configuration of the displacement member.

  38 to 40, the displacement member 3 of the acceleration sensor 100 according to the present embodiment includes a movable electrode 7, an inertial mass body 31, a detection frame portion 32, a torsion beam 33, a link beam 34, and the like. have.

  The torsion beam 33 is supported by the substrate 1 via the anchor member 5. The torsion beam 33 is configured to be twisted about the torsion axis T. The detection frame portion 32 is supported by the torsion beam 33 so as to be rotatable about the torsion axis T. The detection frame part 32 has the movable electrode 7. The link beam 34 is supported by the detection frame portion 32 at a position on an imaginary line L that is shifted from the twist axis T in a plan view.

  The link beam 34 crosses the torsion axis T of the torsion beam 33 with the torsion axis T and moves parallel to the one end side of the detection frame unit 32 by an offset e at the position on the imaginary line L. It is connected with. That is, the absolute value of the offset e is a dimension between the twist axis T and the imaginary line L.

  The inertia mass body 31 is supported by the link beam 34 so as to be displaceable in the thickness direction of the substrate 1 with respect to the substrate 1. The displacement of the connection portion between the link beam 34 and the inertia mass body 31 and the displacement of the connection portion between the link beam 34 and the detection frame portion 32 are configured to be the same. The inertia mass body 31 is configured to surround the fixing member 2 and the detection frame portion 32. A detection electrode 8 is formed on the substrate 1 facing the detection frame portion 32. As shown in FIG. 39, the detection electrode 8 is formed on one side with respect to the anchor member 5.

  In addition, since the structure of this embodiment other than this is the same as that of Embodiment 1 mentioned above, the same code | symbol is attached | subjected about the same element and the description is not repeated. In addition, since the present embodiment can be manufactured by the same manufacturing method as that of the first embodiment, the description thereof will not be repeated.

Next, the operation of the acceleration sensor according to the present embodiment will be described.
Referring to FIG. 41, when acceleration AZ in the direction of detection axis DA is applied to acceleration sensor 100 of the present embodiment, torsion beam 33 is deformed and applied to displacement member 3 excluding torsion beam 33 by acceleration AZ. The inertial mass body 31 is displaced to a position where the working force and the restoring force of the torsion beam 33 are balanced. The inertial mass body 31 is displaced in the direction opposite to the direction of the acceleration AZ.

  The link beam 34 connected to the inertial mass body 31 is also integrated with the inertial mass body 31 and displaced in the direction opposite to the acceleration AZ. Due to the displacement of the link beam 34 with respect to the acceleration AZ, the detection frame unit 32 receives a force in the direction of the imaginary line L of the link beam 34 in the direction opposite to the acceleration AZ. As a result, the detection frame part 32 is rotationally displaced.

  That is, the detection frame portion 32 is rotationally displaced in the direction of the arrow R in the figure so that the upper surface of the detection frame portion 32 faces one end side (left side in FIG. 41) of the acceleration sensor 100. Since the distance between the detection frame unit 32 and the detection electrode 8 is reduced by the rotational displacement of the detection frame unit 32, the capacitance Cd formed by the detection frame unit 32 and the detection electrode 8 increases. The acceleration AZ is detected from the change in the capacitance Cd. Further, the movable electrode 7 is rotationally displaced with the rotational displacement of the detection frame portion 32.

  Next, an operation in which the electrostatic force due to the potential difference between the fixed electrode 6 and the movable electrode 7 affects the displacement of the displacement member 3 will be described.

  Since the movable electrode 7 and the fixed electrode 6 are opposed to each other at one end side and the other end side of the detection frame portion 32, the facing area between the fixed electrode 6 and the movable electrode 7 is the thickness direction of the substrate 1 of the movable electrode 7. Is proportional to the dimension 2Hm.

  42A to 42E, the upper part of each figure shows the arrangement of the fixed electrode 6 and the movable electrode 7 on one side of the detection frame part 32, and the lower part of each figure shows the detection frame part 32. The arrangement of the fixed electrode 6 and the movable electrode 7 on the other side is shown. Since the movable electrode 7 is rotationally displaced along with the rotational displacement of the detection frame portion 32, the movable electrode 7 on one side and the movable electrode 7 on the other side of the detection frame portion 32 are displaced in the opposite directions. The difference between the dimension Hm of the movable electrode 7 in the thickness direction of the substrate 1 and the dimension Hb of the fixed electrode 6 in the thickness direction of the substrate 1 is ΔH. The fixed electrode 6 and the movable electrode 7 include a height difference between an end surface of the fixed electrode 6 on the substrate 1 side and an end surface of the movable electrode 7 on the substrate 1 side, and an end surface of the fixed electrode 6 opposite to the substrate 1 and the movable electrode 7. The difference in height from the opposite end surface of the substrate 1 is ΔH / 2.

  Referring to FIGS. 42B to 42D, detection is performed when the displacement Zr of the movable electrode 7 on one side of the detection frame portion 32 is in a range of −ΔH / 2 ≦ Zr ≦ + ΔH / 2 (a region where acceleration is small). Even if the movable electrode 7 on one side and the other side of the frame portion 32 is displaced, the facing area between the fixed electrode 6 and the movable electrode 7 is constant and does not change, so the capacitance Ci with respect to the displacement Zr of the movable electrode 7 changes. do not do. Referring to FIGS. 42A and 42E, in a region where the absolute value of displacement Zr of movable electrode 7 on one side of detection frame portion 32 exceeds ΔH / 2 (region where acceleration is large), movable electrode 7 is When displaced, the opposing area between the fixed electrode 6 and the movable electrode 7 changes, and the capacitance Ci changes. For this reason, an electrostatic force Fele is generated that is proportional to the displacement differential (∂Ci / ∂Zr) of the capacitance Ci and the square of the potential difference.

  In the above description, the detection electrode 8 is formed on one side with respect to the anchor member 5 as shown in FIG. 39, but the detection electrode 8 may be formed on both sides with respect to the anchor member 5. Referring to FIG. 43, detection electrode 8L and detection electrode 8R are formed on substrate 1 facing detection frame portion 32 so as to sandwich anchor member 5 therebetween.

  Therefore, a change in capacitance is detected from the difference between the capacitance CdL constituted by the detection electrode 8L and the detection frame portion 32 and the capacitance CdR constituted by the detection electrode 8R and the detection frame portion 32. Can do. When the acceleration AZ in the direction of the detection axis DA is applied to the acceleration sensor 100, the detection frame portion 32 rotates around the torsion axis T of the torsion beam 33.

  For this reason, one of the electrostatic capacitance CdL and the electrostatic capacitance CdR becomes larger and the other becomes smaller. That is, since the changes in the capacitance CdL and the capacitance CdR have different signs, the sensitivity to the applied acceleration AZ can be increased.

  Further, the fixed electrode 6 and the movable electrode 7 of the present embodiment may adopt the configurations of the fixed electrode 6 and the movable electrode 7 of the second embodiment.

Next, the function and effect of the acceleration sensor according to the present embodiment will be described.
According to the acceleration sensor 100 of the present embodiment, the displacement member 3 is supported by the substrate 1 and twisted with the torsion beam 33 twisted about the torsion axis T, and the torsion beam 33 so as to be rotatable about the torsion axis T. The detection frame portion 32 supported by the detection frame portion 32 and having the movable electrode 7; the link beam 34 supported by the detection frame portion 32 at a position on the virtual line L shifted from the twist axis T in plan view; And an inertial mass body 31 supported by a link beam 34 so as to be displaceable in the thickness direction of the substrate 1.

  Thereby, since the displacement of the inertial mass body 31 with respect to acceleration can be increased, the displacement of the movable electrode 7 can be increased. Moreover, the inertia mass body 31 can be enlarged. Therefore, a wide range of accelerations can be detected.

(Embodiment 5)
The acceleration sensor according to the fifth embodiment of the present invention is mainly different from the acceleration sensor according to the first embodiment in that it further includes a voltage application electrode for moving the inertial mass body with respect to the substrate. Yes.

  44 to 46, the voltage applying electrode 10 is formed on the substrate 1 via the insulator 9 so as to face the inertial mass body 31. The voltage application electrode 10 is configured to be applied with a voltage in order to move the displacement member 3 in the thickness direction of the substrate 1 with respect to the substrate 1. The fixed electrode 6 and the movable electrode 7 are configured such that the height of the upper surface in the thickness direction of the substrate 1 is the same. That is, the end surface of the movable electrode 7 opposite to the substrate 1 and the end surface of the fixed electrode 6 opposite to the substrate 1 are configured to have the same height with respect to the substrate 1.

  In addition, since the structure of this embodiment other than this is the same as that of Embodiment 1 mentioned above, the same code | symbol is attached | subjected about the same element and the description is not repeated.

  Referring to FIG. 47, when a voltage is applied between voltage application electrode 10 and displacement member 3, an electrostatic force due to capacitance Cv is generated between voltage application electrode 10 and displacement member 3. . With this electrostatic force, the movable electrode 7 is moved so that the difference in height between the upper surface and the lower surface of the fixed electrode 6 and the movable electrode 7 becomes ΔH / 2 in a state where no acceleration is applied.

  According to the acceleration sensor 100 of the present embodiment, since the displacement member 3 is further provided with the voltage application electrode 10 to which a voltage is applied in order to move the displacement member 3 in the thickness direction of the substrate 1, the fixed electrode 6. Even when the upper surface of the movable electrode 7 in the thickness direction of the substrate 1 is formed to have the same height, an electrostatic force caused by the capacitance Cv is generated between the voltage application electrode 10 and the displacement member 3. Thus, a difference in height between the upper surface and the lower surface of the fixed electrode 6 and the movable electrode 7 can be generated in a state where no acceleration is applied. Thereby, the acceleration can be accurately detected in both directions of the applied acceleration.

  Since the heights of the upper surfaces of the fixed electrode 6 and the movable electrode 7 in the thickness direction of the substrate 1 can be formed to be the same, the heights of the upper surfaces of the fixed electrode 6 and the movable electrode 7 in the thickness direction of the substrate 1 are different. In comparison, since the number of film formation, patterning and etching can be reduced by one in the manufacturing process, the manufacturing process can be simplified. In addition, productivity including manufacturing cost can be improved.

(Embodiment 6)
The acceleration sensor according to the sixth embodiment of the present invention is mainly different from the acceleration sensor according to the fourth embodiment in the configuration of the fixed electrode and the movable electrode.

  Referring to FIG. 48, in acceleration sensor 100 of the present embodiment, movable electrode 7 includes a plurality of movable electrode portions 71 separated from each other. The fixed electrode 6 includes a plurality of fixed electrode portions 61 separated from each other. The plurality of movable electrode portions 71 and the plurality of fixed electrode portions 61 have at least two sets P of the movable electrode portions 71 and the fixed electrode portions 61 arranged so as to face each other. The set P may be composed of two fixed electrode portions 61 and one movable electrode portion 71, or may be composed of one fixed electrode portion 61 and one movable electrode portion 71.

  The plurality of movable electrode portions 71 and the plurality of fixed electrode portions 61 are end surfaces opposite to all the substrates 1 of the plurality of movable electrode portions 71 and end surfaces opposite to all the substrates 1 of the plurality of fixed electrode portions 61. Are configured to have the same height with respect to the substrate 1. In addition, the plurality of movable electrode portions 71 and the plurality of fixed electrode portions 61 are connected to the substrate 1 on the end surfaces of all of the plurality of movable electrode portions 71 on the substrate 1 side and on the end surfaces of all of the plurality of fixed electrode portions 61 on the substrate 1 side. You may be comprised so that height may become the same height.

  In the plurality of sets P, when the displacement member 3 is displaced in the thickness direction of the substrate 1 in a region where the acceleration is small, of the at least two sets P, the movable electrode portion 71 of one set P and the movable set P of the other set P are movable. When the electrode portion 71 is displaced in the direction opposite to the thickness direction of the substrate 1, the opposing area of the movable electrode portion 71 and the fixed electrode portion 61 is constant in one set P and the other in the region where the acceleration is small. In the set P, the facing area between the movable electrode portion 71 and the fixed electrode portion 61 is changed.

  In the acceleration sensor 100 according to the present embodiment, the total change in electrostatic force between the movable electrode portion 71 and the fixed electrode portion 61 of the plurality of sets P is smaller in a region where acceleration is small than in a region where acceleration is large. It is configured to be small.

  In addition, since the structure other than this of this Embodiment is the same as that of the structure of Embodiment 4 mentioned above, about the same element, the same code | symbol is attached | subjected and the description is not repeated. In addition, since the present embodiment can be manufactured by the same manufacturing method as that of the first embodiment, the description thereof will not be repeated.

  Next, an operation in which the electrostatic force due to the potential difference between the fixed electrode 6 and the movable electrode 7 affects the displacement of the displacement member 3 will be described.

  49A to 49E, the upper part of each figure shows the arrangement of the fixed electrode part 61 and the movable electrode part 71 on one side of the detection frame part 32, and the lower part of each figure shows the detection frame part. The arrangement of the fixed electrode portion 61 and the movable electrode portion 71 on the other side of 32 is shown. Since the movable electrode portion 71 is rotationally displaced along with the rotational displacement of the detection frame portion 32, the movable electrode portion 71 on one side and the movable electrode portion 71 on the other side of the detection frame portion 32 are displaced in the opposite directions. The fixed electrode unit 61 and the movable electrode unit 71 are configured such that a height difference ΔP with respect to the substrate 1 is generated between the end surface of the fixed electrode unit 61 on the substrate 1 side and the end surface of the movable electrode unit 71 on the substrate 1 side. ing.

  As shown in FIG. 49C, when the displacement Zr of the movable electrode portion 71 on one side and the other side of the detection frame portion 32 is 0, the fixed electrode portion 61 on the one side and the other side of the detection frame portion 32. Since the facing area between the movable electrode portion 71 is constant and does not change, the capacitance Ci with respect to the displacement Zr of the movable electrode 7 does not change. Therefore, no electrostatic force is generated.

  As shown in FIGS. 49B and 49D, in the region where the displacement Zr of the movable electrode 7 on one side and the other side of the detection frame portion 32 is −ΔP ≦ Zr ≦ + ΔP (region where acceleration is small), Even if the movable electrode 7 on one side and the other side of the detection frame portion 32 is displaced, the opposing area of the movable electrode portion 71 and the fixed electrode portion 61 is constant and does not change in one set P. The change of the electrostatic capacity Ci with respect to Zr becomes small. Therefore, the total change in electrostatic force between the movable electrode portions 71 and the fixed electrode portions 61 of the plurality of sets P is smaller than that in a region where acceleration is large.

  As shown in FIGS. 49A and 49E, in the region where the absolute value of the displacement Zr of the movable electrode 7 on one side and the other side of the detection frame portion 32 exceeds ΔP (region where acceleration is large), the movable electrode When 7 is displaced, the opposing area between the fixed electrode portion 61 and the movable electrode portion 71 is changed in both the one set P and the other set P, so that the capacitance Ci with respect to the displacement Zr of the movable electrode 7 is changed. For this reason, the total change of the electrostatic force between the movable electrode portion 71 and the fixed electrode portion 61 of the plurality of sets P becomes large.

  According to the acceleration sensor 100 of the present embodiment, the end surfaces of the plurality of movable electrode portions 71 opposite to all the substrates 1 and the end surfaces of the plurality of fixed electrode portions 61 opposite to all the substrates 1 are substrates 1. , And the height of all the movable electrode portions 71 on the substrate 1 side and the height of all the fixed electrode portions 61 on the substrate 1 side with respect to the substrate 1 are the same height. It is configured as follows. For this reason, compared with the case where the height of the end surface of the thickness direction of the board | substrate 1 of the fixed electrode part 61 and the movable electrode part 71 differs, the frequency | count of film-forming, patterning, and an etching can be reduced once in a manufacturing process. Therefore, the manufacturing process can be simplified. In addition, productivity including manufacturing cost can be improved.

  Further, when the displacement member 3 is displaced in the thickness direction of the substrate 1 in a region where the acceleration is small, the movable electrode portion 71 of one set P and the other set P out of at least two sets P. The movable electrode portion 71 is displaced in the direction opposite to each other in the thickness direction of the substrate 1, so that in one region P, the opposing area of the movable electrode portion 71 and the fixed electrode portion 61 is constant in a region where the acceleration is small. In the other set P, the facing area between the movable electrode portion 71 and the fixed electrode portion 61 is changed.

  For this reason, in the region where acceleration is small, the opposing area of the movable electrode portion 71 and the fixed electrode portion 61 is constant and does not change in one set P, and therefore the change in the capacitance Ci with respect to the displacement Zr of the movable electrode 7 is small. Become. Therefore, in the region where the acceleration is small, the total change in electrostatic force between the movable electrode portions 71 and the fixed electrode portions 61 of the plurality of sets P is small compared to the region where the acceleration is large. In a region where acceleration is large, since the opposing area of the fixed electrode portion 61 and the movable electrode portion 71 changes in both the one set P and the other set P, the capacitance Ci with respect to the displacement Zr of the movable electrode 7 changes. To do. For this reason, the total change of the electrostatic force between the movable electrode portion 71 and the fixed electrode portion 61 of the plurality of sets P becomes large. Therefore, since the rigidity is higher in a region where acceleration is large than in a region where acceleration is small, a wide range of acceleration can be detected.

  According to the acceleration sensor 100 of the present embodiment, the displacement member 3 is supported by the substrate 1 and twisted with the torsion beam 33 twisted about the torsion axis T, and the torsion beam 33 so as to be rotatable about the torsion axis T. The detection frame portion 32 supported by the detection frame portion 32 and having the movable electrode 7; the link beam 34 supported by the detection frame portion 32 at a position on the virtual line L shifted from the twist axis T in plan view; And an inertial mass body 31 supported by a link beam 34 so as to be displaceable in the thickness direction of the substrate 1.

  Thereby, since the displacement of the inertial mass body 31 with respect to acceleration can be increased, the displacement of the movable electrode 7 can be increased. Moreover, the inertia mass body 31 can be enlarged. Therefore, a wide range of accelerations can be detected.

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

  DESCRIPTION OF SYMBOLS 1 Board | substrate, 2 Fixed member, 3 Displacement member, 4 Beam member, 5 Anchor member, 6 Fixed electrode, 7 Movable electrode, 8 Detection electrode, 9 Insulator, 10 Voltage application electrode, 31 Inertial mass body, 61 Movable electrode part, 71 Fixed electrode part, 100 Accelerometer, L virtual line, P group, P1 first group, P2 second group, T twist axis.

Claims (10)

A substrate,
A displacement member supported on the surface of the substrate so as to be displaceable in the thickness direction of the substrate with respect to the substrate, and having a movable electrode;
A fixed electrode arranged to face the movable electrode and for generating an electrostatic force between the movable electrode,
In the region where the acceleration is small, even if the displacement member is displaced in the thickness direction of the substrate, the facing area between the movable electrode and the fixed electrode is constant, and in the region where the acceleration is large, the displacement member is the thickness of the substrate. When the displacement in the direction is configured to change the facing area of the movable electrode and the fixed electrode ,
The movable electrode includes a plurality of movable electrode portions separated from each other,
The fixed electrode includes a plurality of fixed electrode portions separated from each other,
The plurality of movable electrode portions and the plurality of fixed electrode portions have a plurality of sets of the movable electrode portions and the fixed electrode portions arranged to face each other,
In a region where the acceleration is small, even if the displacement member is displaced in the thickness direction of the substrate, the total of the opposed areas of the plurality of sets of the movable electrode portion and the fixed electrode portion is constant, and
When the displacement member is displaced in the thickness direction of the substrate in a region where the acceleration is large, the total of the opposing areas of the plurality of the movable electrode portions and the fixed electrode portions is changed.
The plurality of sets are formed by the movable electrode portion being displaced in the thickness direction of the substrate in a region where acceleration is small.
A set in which the facing area of the movable electrode portion and the fixed electrode portion is increased;
Opposing area between said fixed electrode portion and the movable electrode portion and a smaller group, acceleration sensors. The movable electrode portion and the fixed electrode portion have the same dimension in the thickness direction of the substrate,
The plurality of sets are
A first set configured such that the movable electrode portion is positioned below the fixed electrode portion with respect to the substrate;
Wherein said movable electrode portion with respect to the substrate and a second set that is configured to be positioned above said fixed electrode portion, the acceleration sensor according to claim 1. The displacement member is
A beam member supported by the substrate;
Supported by the beam member displaceable in the thickness direction of the substrate relative to the substrate, and an inertial mass having a movable electrode, an acceleration sensor according to claim 1 or 2. The displacement member is
A torsion beam supported by the substrate and twisted about a torsion axis;
A detection frame portion supported by the torsion beam so as to be rotatable about the torsion axis; and
A link beam supported by the detection frame portion at a position on an imaginary line deviated from the twist axis in plan view;
The displaceably the thickness direction of the substrate relative to the substrate is supported by the link beams, and and an inertial mass having a movable electrode, an acceleration sensor according to claim 1 or 2. The displacement member is
A torsion beam supported by the substrate and twisted about a torsion axis;
A detection frame part supported by the torsion beam so as to be rotatable about the torsion axis and having the movable electrode;
A link beam supported by the detection frame portion at a position on an imaginary line deviated from the twist axis in plan view;
And a displaceably said link supported beam inertial mass body in the thickness direction of the substrate relative to the substrate, the acceleration sensor according to claim 1 or 2. The movable electrode is configured such that the end surface of the movable electrode opposite to the substrate and the end surface of the fixed electrode opposite to the substrate have the same height with respect to the substrate.
The apparatus further comprises a voltage application electrode formed on the substrate so as to face the displacement member and to which a voltage is applied to move the displacement member relative to the substrate in the thickness direction of the substrate. Item 6. The acceleration sensor according to any one of Items 1 to 5 . The acceleration sensor according to any one of said movable electrode and the fixed electrode are arranged to face in a direction along the surface of the substrate, according to claim 1-6. Wherein disposed on said surface of said substrate to the displacement member and the counter, and further comprising a detection electrode constituting the displacement member and the electrostatic capacitance, the acceleration sensor according to any of claims 1-7. A substrate,
A displacement member supported on the surface of the substrate so as to be displaceable in the thickness direction of the substrate with respect to the substrate, and having a movable electrode;
A fixed electrode arranged to face the movable electrode and for generating an electrostatic force between the movable electrode,
The movable electrode includes a plurality of movable electrode portions separated from each other,
The fixed electrode includes a plurality of fixed electrode portions separated from each other,
The plurality of movable electrode portions and the plurality of fixed electrode portions have at least two sets of the movable electrode portion and the fixed electrode portion arranged to face each other,
The heights of the end surfaces of the plurality of movable electrode portions opposite to the substrates and the end surfaces of the plurality of fixed electrode portions opposite to the substrates with respect to the substrates, and the plurality of movable electrode portions All of the substrate-side end surfaces and all of the substrate-side end surfaces of the plurality of fixed electrode portions are configured to have the same height with respect to the substrate,
When the displacement member is displaced in the thickness direction of the substrate in a region where the acceleration is small, the plurality of the groups are at least two of the groups, and the movable electrode portion of one of the groups and the other of the groups are When the movable electrode portion is displaced in the opposite direction to the thickness direction of the substrate, the opposing area of the movable electrode portion and the fixed electrode portion is constant in one set and the other in the region where acceleration is small. In the set, the opposed area of the movable electrode portion and the fixed electrode portion is configured to change,
An acceleration sensor configured to reduce a total change in electrostatic force between the plurality of the movable electrode portions and the fixed electrode portions in the plurality of sets in a region where acceleration is small compared to a region where acceleration is large. . The displacement member is
A torsion beam supported by the substrate and twisted about a torsion axis;
A detection frame part supported by the torsion beam so as to be rotatable about the torsion axis and having the movable electrode;
A link beam supported by the detection frame portion at a position on an imaginary line deviated from the twist axis in plan view;
The acceleration sensor according to claim 9 , further comprising an inertia mass body supported by the link beam so as to be displaceable in the thickness direction of the substrate with respect to the substrate.

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