JP2016044979A - Physical quantity sensor, electronic apparatus, and movable body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a physical quantity sensor which can prevent occurrence of sticking and reduce capacity off-set, an electronic apparatus and a movable body with the physical quantity sensor.SOLUTION: A physical quantity sensor 100 according to the present invention includes: a base plate 10; a supporting part 40; a movable part 20 connected to the supporting part 40 with connecting parts 30 and 32; fixed electrodes 50 and 52 for the base plate 10 facing the movable part 20, and dummy electrodes 53, 54, and 55, the movable part 20 having a first mass part 20a, a second mass part 20b with mass larger than that of the first mass part 20a, a first movable electrode 21 in the first mass part 20a, and a second movable electrode 22 in the second mass part 20b, and the fixed electrodes 50 and 52 and the dummy electrodes 53, 54, and 55 serving to reduce the capacity off-set.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a physical quantity sensor, an electronic device, and a moving object.

  In recent years, for example, a physical quantity sensor that detects a physical quantity such as acceleration has been developed by using, for example, silicon MEMS (Micro Electro Mechanical Systems) technology.

  This physical quantity sensor has a large plate portion and a small plate portion, a movable electrode supported by the insulating layer so that they can swing in a seesaw shape, and an insulating layer facing the large plate portion. One having a fixed electrode provided and a fixed electrode provided on an insulating layer so as to face the small plate portion is known (for example, see Patent Document 1).

  In the physical quantity sensor described in Patent Document 1, when a structure (Si structure) having a movable electrode is anodically bonded to a glass substrate, the electrostatic force generated is large if the exposed glass surface facing the structure is large. Therefore, there is a problem that sticking (sticking) of the structure to the glass substrate occurs.

  In order to solve such a problem, an attempt has been made to provide a counter electrode (dummy electrode) having the same potential as that of the movable electrode so as to prevent the movable body from sticking to the substrate (for example, Patent Document 2). reference).

  However, in the physical quantity sensor of Patent Document 2, the occurrence of sticking of the movable electrode can be reduced by the dummy electrode, but a difference in capacitance (capacitance offset) between each fixed electrode and the movable electrode is generated. Depending on the variation, the yield may deteriorate beyond the IC (integrated circuit) adjustment range. In addition, the capacitance offset affects each of the entire sensor (for example, see Patent Document 3).

JP 2007-298405 A JP2013-160554A Japanese Patent Laid-Open No. 2002-202320

  An object of the present invention is to provide a physical quantity sensor capable of preventing the occurrence of sticking and reducing a capacity offset, and an electronic apparatus and a moving body including the physical quantity sensor.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
The physical quantity sensor of the present invention includes a substrate,
A support fixed to the substrate;
A movable part connected to the support part via a connecting part and swingable relative to the support part;
A fixed electrode disposed on the substrate so as to face the movable part,
The movable part is arranged on the first mass part provided on one side with respect to the connecting part, a second mass part provided on the other side and having a mass larger than the first mass part, and the first mass part. A first movable electrode, and a second movable electrode disposed on the second mass part,
The fixed electrode is opposed to the first fixed part, the first fixed electrode disposed opposite to the first mass part, the second fixed electrode disposed opposite to the second mass part, the movable part, and A dummy electrode disposed so as not to contact the first fixed electrode and the second fixed electrode, and having the same potential as the movable part,
The dummy electrode includes a first dummy electrode provided between the first fixed electrode and the second fixed electrode, and a second dummy electrode provided on the opposite side of the first fixed electrode from the first dummy electrode. A dummy electrode, and a third dummy electrode provided on the opposite side of the second fixed electrode from the first dummy electrode,
Capacitance when the separation distance between the first fixed electrode and the first dummy electrode and the second dummy electrode is equal to the separation distance between the second fixed electrode and the first dummy electrode and the third dummy electrode The fixed electrode and the dummy electrode are arranged so that the capacitance offset is smaller than the offset.

  Thereby, it is possible to prevent the occurrence of sticking and to reduce the capacity offset.

[Application Example 2]
In the physical quantity sensor of the present invention, the separation distance between the first fixed electrode and the first dummy electrode is w1, the separation distance between the second fixed electrode and the first dummy electrode is w2, and the first fixed electrode and the first dummy electrode are It is preferable that the relationship of w1 <w2 and w3 = w4 is satisfied, where w3 is the separation distance from the second dummy electrode and w4 is the separation distance between the second fixed electrode and the third dummy electrode.
Thereby, the capacity offset can be reduced more easily.

[Application Example 3]
In the physical quantity sensor of the present invention, the separation distance between the first fixed electrode and the first dummy electrode is w1, the separation distance between the second fixed electrode and the first dummy electrode is w2, and the first fixed electrode and the first dummy electrode are It is preferable that the relationship of w1 <w2 and w3 <w4 is satisfied, where w3 is the separation distance from the second dummy electrode and w4 is the separation distance between the second fixed electrode and the third dummy electrode.
Thereby, the capacity offset can be reduced more easily.

[Application Example 4]
In the physical quantity sensor of the present invention, the separation distance between the first fixed electrode and the first dummy electrode is w1, the separation distance between the second fixed electrode and the first dummy electrode is w2, and the first fixed electrode and the first dummy electrode are It is preferable that the relationship of w1 <w2, w3> w4 is satisfied, where w3 is the separation distance from the second dummy electrode and w4 is the separation distance between the second fixed electrode and the third dummy electrode.
Thereby, the capacity offset can be reduced more easily.

[Application Example 5]
In the physical quantity sensor of the present invention, the separation distance between the first fixed electrode and the first dummy electrode is w1, the separation distance between the second fixed electrode and the first dummy electrode is w2, and the first fixed electrode and the first dummy electrode are It is preferable that the relationship of w1> w2 and w3 <w4 is satisfied, where w3 is the separation distance from the second dummy electrode and w4 is the separation distance between the second fixed electrode and the third dummy electrode.
Thereby, the capacity offset can be reduced more easily.

[Application Example 6]
In the physical quantity sensor of the present invention, the substrate is preferably a glass substrate.

  Thereby, the movable part and the substrate can be easily electrically insulated from each other, and the sensor structure can be simplified.

[Application Example 7]
An electronic apparatus according to the present invention includes the physical quantity sensor according to the present invention.

  Such an electronic device includes the physical quantity sensor according to this application example, and thus can have high reliability.

[Application Example 8]
The moving body of the present invention includes the physical quantity sensor of the present invention.

  Such a moving body includes the physical quantity sensor according to this application example, and thus can have high reliability.

It is a top view which shows typically the physical quantity sensor which concerns on suitable embodiment of this invention. It is the II-II sectional view taken on the line of FIG. 1 which shows the physical quantity sensor 100 of FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1 schematically showing the physical quantity sensor 100 in FIG. 1. FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 1 schematically illustrating the physical quantity sensor 100 in FIG. 1. It is sectional drawing which shows typically the manufacturing process of the physical quantity sensor of FIG. It is sectional drawing which shows typically the manufacturing process of the physical quantity sensor of FIG. It is sectional drawing which shows typically the manufacturing process of the physical quantity sensor of FIG. It is a top view which shows typically the physical quantity sensor which concerns on a modification. 1 is a perspective view illustrating a configuration of a mobile (or notebook) personal computer to which an electronic apparatus of the present invention is applied. It is a perspective view which shows the structure of the mobile telephone (PHS is also included) to which the electronic device of this invention is applied. It is a perspective view which shows the structure of the digital still camera to which the electronic device of this invention is applied. It is a perspective view which shows the structure of the motor vehicle which is an example of the mobile body of this invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a physical quantity sensor, an electronic device, and a moving body of the invention will be described with reference to the accompanying drawings.

[Physical quantity sensor]
First, the physical quantity sensor of FIG. 1 will be described with reference to the drawings.
FIG. 1 is a plan view schematically showing a physical quantity sensor 100 according to a preferred embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1 schematically showing the physical quantity sensor 100 of FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 1 schematically showing the physical quantity sensor 100 of FIG. 1, and FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 1 schematically showing the physical quantity sensor 100 of FIG. .

  For convenience, in FIG. 1, the lid 80 is shown through. In FIGS. 3 and 4, the lid 80 is omitted. 1 to 4 show the X axis, the Y axis, and the Z axis as three axes orthogonal to each other.

  As shown in FIGS. 1 to 4, the physical quantity sensor 100 includes a substrate 10, a movable portion 20, connecting portions 30 and 32, a support portion 40, fixed electrodes 50 and 52, and dummy electrodes 53, 54 and 55. And wirings 60, 64, 66, pads 70, 72, 74, and a lid 80.

  In the present embodiment, an example in which the physical quantity sensor 100 is an acceleration sensor (capacitive MEMS acceleration sensor) that detects acceleration in the vertical direction (Z-axis direction) will be described.

Hereinafter, each part which comprises the physical quantity sensor 100 is demonstrated in detail sequentially.
The material of the substrate 10 is, for example, an insulating material such as glass. For example, when the substrate 10 is made of an insulating material such as glass and the movable portion 20 is made of a semiconductor material such as silicon, the two can be easily electrically insulated, and the sensor structure can be simplified. When the substrate 10 is made of glass, a more sensitive physical quantity sensor can be provided.

  A recess 11 is formed in the substrate 10. Above the recess 11, the movable part 20 and the connecting parts 30 and 32 are provided via a gap. In the example shown in FIG. 1, the planar shape of the recess 11 (the shape viewed from the Z-axis direction) is a rectangle. A post portion 13 is provided on the bottom surface (surface of the substrate 10 defining the recess 11) 12 of the recess 11.

  In the example shown in FIGS. 2 to 4, the post portion 13 is provided integrally with the substrate 10. The post portion 13 protrudes above the bottom surface 12 (+ Z axis direction).

  As shown in FIGS. 3 and 4, in this embodiment, the height of the post portion 13 (the distance between the upper surface 14 and the bottom surface 12 of the post portion 13) and the depth of the recess 11 are configured to be equal. ing.

  The upper surface 14 of the post portion 13 is joined to the support portion 40. A recess 15 is formed on the upper surface 14 of the post portion 13. A first wiring 60 is provided on the bottom surface (the surface of the post portion 13 that defines the recess 15) 16 of the recess 15.

  2 to 4, the side surface of the recess 11 (the side surface of the substrate 10 defining the recess 11) and the side surface of the post portion 13 are perpendicular to the bottom surface 12 of the recess 11, but the bottom surface 12. It may be inclined with respect to.

  The movable part 20 can be displaced around a support shaft (first axis) Q. Specifically, when the acceleration in the vertical direction (Z-axis direction) is applied, the movable unit 20 swings the seesaw using the support shaft Q determined by the connecting portions 30 and 32 as the rotation axis (swing shaft). The support axis Q is, for example, parallel to the Y axis. In the illustrated example, the planar shape of the movable portion 20 is a rectangle. The thickness (size in the Z-axis direction) of the movable unit 20 is constant, for example.

The movable part 20 has a first mass part 20a and a second mass part 20b.
The first mass part 20a is one of the two parts of the movable part 20 defined by the support shaft Q (a part located on the right side in FIG. 1) in plan view.

  The second mass part 20b is the other of the two parts of the movable part 20 defined by the support shaft Q (a part located on the left side in FIG. 1) in plan view.

  When acceleration in the vertical direction (for example, gravitational acceleration) is applied to the movable unit 20, a rotational moment (moment of force) is generated in each of the first mass unit 20a and the second mass unit 20b. Here, when the rotational moment (for example, clockwise rotational moment) of the first mass portion 20a and the rotational moment of the second mass portion 20b (for example, counterclockwise rotational moment) are balanced, the inclination of the movable portion 20 is increased. No change occurs and acceleration cannot be detected. Therefore, when the acceleration in the vertical direction is applied, the movable part is arranged such that the rotational moment of the first mass part 20a and the rotational moment of the second mass part 20b are not balanced and a predetermined inclination occurs in the movable part 20. 20 is designed.

  In the physical quantity sensor 100, by disposing the support shaft Q at a position deviating from the center (center of gravity) of the movable portion 20 (by making the distance from the support shaft Q to the tip of each mass unit 20a, 20b different), The mass parts 20a and 20b have different masses. That is, the movable unit 20 has a mass different from one side (first mass unit 20a) and the other side (second mass unit 20b) with the support axis Q as a boundary. In the illustrated example, the distance from the support shaft Q to the end surface 23 of the first mass unit 20a is smaller than the distance from the support shaft Q to the end surface 24 of the second mass unit 20b. Moreover, the thickness of the 1st mass part 20a and the thickness of the 2nd mass part 20b are equal. Therefore, the mass of the first mass unit 20a is smaller than the mass of the second mass unit 20b. Thus, when the mass parts 20a and 20b have different masses, when the acceleration in the vertical direction is applied, the rotational moment of the first mass part 20a and the rotational moment of the second mass part 20b are balanced. You can not let it. Therefore, when vertical acceleration is applied, the movable portion 20 can be caused to have a predetermined inclination.

  The movable part 20 is provided apart from the substrate 10. The movable part 20 is provided above the recess 11. In the illustrated example, a gap is provided between the movable portion 20 and the substrate 10. In addition, the movable portion 20 is provided away from the support portion 40 by connecting portions 30 and 32. Thereby, the movable part 20 can be rocked by a seesaw.

  The movable part 20 includes a first movable electrode 21 and a second movable electrode 22 provided with the support axis Q as a boundary. The 1st movable electrode 21 is provided in the 1st mass part 20a. The second movable electrode 22 is provided in the second mass unit 20b.

  The first movable electrode 21 is a portion of the movable portion 20 that overlaps the first fixed electrode 50 in plan view. The first movable electrode 21 forms a capacitance C <b> 1 with the first fixed electrode 50. That is, the capacitance C <b> 1 is formed by the first movable electrode 21 and the first fixed electrode 50.

  The second movable electrode 22 is a portion of the movable portion 20 that overlaps the second fixed electrode 52 in plan view. The second movable electrode 22 forms a capacitance C2 between the second movable electrode 22 and the second fixed electrode 52. That is, the second movable electrode 22 and the second fixed electrode 52 form a capacitance C2. In the physical quantity sensor 100, the movable part 20 is made of a conductive material (silicon doped with impurities), so that the movable electrodes 21 and 22 are provided. That is, the first mass part 20 a functions as the first movable electrode 21, and the second mass part 20 b functions as the second movable electrode 22.

  For example, the electrostatic capacitance C1 and the electrostatic capacitance C2 are configured to be equal to each other in a state where the movable portion 20 shown in FIG. 2 is horizontal. The positions of the movable electrodes 21 and 22 change according to the movement of the movable part 20. The electrostatic capacitances C1 and C2 change according to the positions of the movable electrodes 21 and 22. A predetermined potential is applied to the movable portion 20 via the connecting portions 30 and 32 and the support portion 40.

  The movable part 20 is formed with a through hole 25 penetrating the movable part 20. Thereby, the influence (air resistance) of the air when the movable part 20 swings can be reduced. For example, a plurality of through holes 25 are formed. In the illustrated example, the planar shape of the through hole 25 is a rectangle.

  The movable portion 20 is provided with an opening 26 that penetrates the movable portion 20. The opening 26 is provided on the support shaft Q in plan view. In the opening portion 26, connecting portions 30 and 32 and a support portion 40 are provided. In the illustrated example, the planar shape of the opening 26 is a rectangle. The movable part 20 is connected to the support part 40 via the connecting parts 30 and 32.

  The connection parts 30 and 32 connect the movable part 20 and the support part 40. The connecting portions 30 and 32 function as torsion springs (torsion springs). Thereby, the connection parts 30 and 32 can have a strong restoring force with respect to the torsional deformation which arises in the connection parts 30 and 32 when the movable part 20 rocks a seesaw.

  The connecting portions 30 and 32 are disposed on the support shaft Q in plan view. The connecting portions 30 and 32 extend along the support axis Q. The first connecting part 30 extends from the support part 40 in the + Y axis direction. The second connecting portion 32 extends from the support portion 40 in the −Y axis direction.

  The support portion 40 is disposed in the opening portion 26. The support portion 40 is provided on the support shaft Q in plan view. A part of the support part 40 is joined (connected) to the upper surface 14 of the post part 13. The support part 40 supports the movable part 20 via the connection parts 30 and 32. The support portion 40 is connected to the connecting portions 30 and 32 and is provided along the support axis Q, and a first portion provided on the substrate and provided outside the connection region 46 in plan view. A contact region 63 electrically connected to the wiring 60 is provided.

  The support part 40 has a first part 41 and second parts 42, 43, 44, 45. The support portion 40 has a first portion 41 extending along a second axis R that intersects (specifically, orthogonally) the support axis Q, and the second portions 42, 43, 44, 45 is a protruding shape. The second axis R is an axis parallel to the X axis.

  The first portion 41 of the support portion 40 extends so as to intersect (specifically, orthogonally) the support axis Q. The first portion 41 is joined to the connecting portions 30 and 32. The first portion 41 is provided on the support shaft Q in plan view and is separated from the substrate 10. That is, the portion of the support portion 40 on the support shaft Q is separated from the substrate 10. In the example illustrated in FIG. 1, the planar shape of the first portion 41 is a rectangle. The first portion 41 extends along the second axis R.

  A connection region 46 is provided in the first portion 41 of the support portion 40. In the example illustrated in FIG. 1, the connection region 46 is a region sandwiched between the coupling portions 30 and 32 of the support portion 40 in plan view. In the illustrated example, the planar shape of the connection region 46 is a rectangle. At least a part of the connection region 46 is not fixed to the substrate 10.

  The second portions 42, 43, 44, 45 of the support portion 40 protrude (extend) from the end portion of the first portion 41. In the example shown in FIG. 1, the planar shape of the second portions 42, 43, 44, 45 is a rectangle. A contact region 63 is provided in each of the second portions 42, 43, 44, 45.

  The second portions 42 and 43 of the support portion 40 extend from one end portion of the first portion 41 (specifically, the end portion in the −X axis direction) along the support axis Q in opposite directions. In the illustrated example, the second portion 42 extends in the + Y-axis direction from one end portion of the first portion 41. The second portion 43 extends in the −Y axis direction from one end portion of the first portion 41. A part of the second part 42 and a part of the second part 43 are joined to the post part 13.

  The second portions 44 and 45 of the support portion 40 extend in the opposite directions along the support axis Q from the other end portion (specifically, the end portion in the + X axis direction) of the first portion 41. In the illustrated example, the second portion 44 extends from the other end of the first portion 41 in the + Y-axis direction. The second portion 45 extends from the other end of the first portion 41 in the −Y axis direction. A part of the second part 44 and a part of the second part 45 are joined to the post part 13.

  The support portion 40 includes the above-described portions 41, 42, 43, 44, and 45, and thus has an H-shaped (substantially H-shaped) planar shape. That is, the first portion 41 forms an H-shaped horizontal bar. The second parts 42, 43, 44, 45 constitute an H-shaped vertical bar.

  The movable part 20, the connection parts 30, 32, and the support part 40 are integrally provided. In the illustrated example, the movable portion 20, the connecting portions 30 and 32, and the support portion 40 constitute one structure (silicon structure) 2. The movable part 20, the connecting parts 30, 32, and the support part 40 are integrally provided by patterning one substrate (silicon substrate). The material of the movable part 20, the connecting parts 30, 32, and the support part 40 is, for example, silicon provided with conductivity by doping impurities such as phosphorus and boron. When the material of the substrate 10 is glass and the material of the movable portion 20, the connecting portions 30, 32, and the support portion 40 is silicon, the substrate 10 and the support portion 40 are joined by, for example, anodic bonding.

  In the physical quantity sensor 100, the structure 2 is fixed to the substrate 10 by one support portion 40. That is, the structure 2 is fixed to the substrate 10 at one point (one support portion 40). Therefore, for example, compared to a configuration in which the structure is fixed to the substrate at two points (two support portions), stress generated by the difference between the thermal expansion coefficient of the substrate 10 and the thermal expansion coefficient of the structure 2, The influence which the stress etc. which are added to a device at the time of mounting give to connecting parts 30 and 32 can be reduced.

  The fixed electrodes 50 and 52 are provided on the substrate 10. In the illustrated example, the fixed electrodes 50 and 52 are provided on the bottom surface 12 of the recess 11. The first fixed electrode 50 is disposed to face the first movable electrode 21. Above the first fixed electrode 50, the first movable electrode 21 is located via a gap. The second fixed electrode 52 is disposed to face the second movable electrode 22. Above the second fixed electrode 52, the second movable electrode 22 is located via a gap. The area of the first fixed electrode 50 and the area of the second fixed electrode 52 are, for example, equal. The planar shape of the first fixed electrode 50 and the planar shape of the second fixed electrode 52 are symmetric with respect to the support axis Q, for example.

  The dummy electrodes 53, 54, 55 are provided on the substrate 10 so as not to contact the fixed electrodes 50, 52. The dummy electrodes 53, 54, and 55 are configured to have the same potential as the movable unit 20.

  The first dummy electrode 53 is provided between the first fixed electrode 50 and the second fixed electrode 52. The second dummy electrode 54 is provided on the opposite side of the first fixed electrode 50 from the first dummy electrode 53. The third dummy electrode 55 is provided on the opposite side of the second fixed electrode 52 from the first dummy electrode 53.

  The material of the fixed electrodes 50 and 52 and the dummy electrodes 53, 54, and 55 is, for example, aluminum, gold, or ITO (Indium Tin Oxide). The material of the fixed electrodes 50, 52 and the dummy electrodes 53, 54, 55 is preferably a transparent electrode material such as ITO. When the substrate 10 is a transparent substrate (glass substrate) by using a transparent electrode material as the fixed electrodes 50, 52 and the dummy electrodes 53, 54, 55, the fixed electrodes 50, 52, the dummy electrodes 53, 54, 55 This is because foreign matters and the like existing in the can be easily visually recognized.

  The first wiring 60 is provided on the substrate 10. The first wiring 60 has a wiring layer portion 61 and a bump portion 62.

  The wiring layer portion 61 of the first wiring 60 connects the first pad 70 and the bump portion 62. In the illustrated example, the wiring layer portion 61 extends from the first pad 70 to the bump portion 62 through the first groove portion 17, the recess portion 11, and the recess portion 15 formed in the substrate 10. The portion provided in the recess 15 of the wiring layer portion 61 overlaps the support portion 40 in plan view. In the illustrated example, the planar shape of the portion provided in the recess 15 of the wiring layer portion 61 is H-shaped (substantially H-shaped). The material of the wiring layer portion 61 is the same as the material of the fixed electrodes 50 and 52, for example.

  The bump part 62 of the first wiring 60 is provided on the wiring layer part 61. The bump part 62 connects the wiring layer part 61 and the support part 40 in the contact region 63. That is, the contact region 63 is a region where the first wiring 60 and the support portion 40 are connected (contacted). More specifically, the contact region 63 is a region (contact surface) in contact with the support portion 40 of the bump portion 62. The material of the bump part 62 is, for example, aluminum, gold, or platinum.

  The contact region 63 is arranged avoiding the support shaft Q. That is, the contact region 63 is arranged away from the support shaft Q. In plan view, at least one contact region 63 is provided on one side (specifically on the + X axis direction side) and the other side (specifically on the −X axis direction side) with the support axis Q as a boundary. ing. The contact regions 63 are provided on both sides of the connection region 46 with the support axis Q as a boundary in plan view. In the illustrated example, four contact regions 63 are provided, and are provided so as to overlap the second portions 42, 43, 44, 45 of the support portion 40 in plan view. That is, the contact region 63 is provided so as to overlap each end of the vertical bar of the support portion 40 having an H shape (substantially H shape) in plan view. In the illustrated example, the planar shape of the contact region 63 is a rectangle.

  As shown in FIGS. 3 and 4, the contact region 63 is located above the upper surface 14 (joint surface between the post portion 13 and the support portion 40) 14 of the post portion 13. Specifically, when the silicon substrate is bonded to the substrate 10 (details will be described later), the silicon substrate is pushed and depressed by the bump portion 62 of the first wiring 60, and the contact region 63 is the upper surface 14 of the post portion 13. It is located above. For example, when the support portion 40 is pressed by the bump portion 62 (the silicon substrate), stress is generated in the support portion 40.

  Although not shown, if the first wiring 60 and the support portion 40 are in contact, the support portion 40 is not depressed, and the contact region 63 and the upper surface 14 of the post portion 13 are the same in the Z-axis direction. May be in position. That is, the contact region 63 and the upper surface 14 may have the same height. Even in such a form, the first wiring 60 and the support portion 40 come into contact with each other, so that stress is generated in the support portion 40.

  The second wiring 64 is provided on the substrate 10. The second wiring 64 connects the second pad 72 and the first fixed electrode 50. In the illustrated example, the second wiring 64 extends from the second pad 72 to the first fixed electrode 50 through the second groove 18 and the recess 11. The material of the second wiring 64 is the same as the material of the fixed electrodes 50 and 52, for example.

  The third wiring 66 is provided on the substrate 10. The third wiring 66 connects the third pad 74 and the second fixed electrode 52. In the illustrated example, the third wiring 66 extends from the third pad 74 to the second fixed electrode 52 through the third groove 19 and the recess 11. The material of the third wiring 66 is the same as the material of the fixed electrodes 50 and 52, for example.

  The pads 70, 72, and 74 are provided on the substrate 10. In the illustrated example, the pads 70, 72, and 74 are provided in the groove portions 17, 18, and 19, respectively, and are connected to the wirings 60, 64, and 66. The pads 70, 72, and 74 are provided at positions that do not overlap the lid 80 in plan view. Thereby, even in a state where the movable portion 20 is housed in the substrate 10 and the lid 80, the capacitances C1 and C2 can be detected by the pads 70, 72, and 74. The material of the pads 70, 72, 74 is the same as that of the fixed electrodes 50, 52, for example.

  The lid 80 is provided on the substrate 10. The lid 80 is bonded to the substrate 10. The lid 80 and the substrate 10 form a cavity 82 that houses the movable portion 20. The cavity 82 is, for example, an inert gas (for example, nitrogen gas) atmosphere. The material of the lid 80 is, for example, silicon. When the material of the lid 80 is silicon and the material of the substrate 10 is glass, the substrate 10 and the lid 80 are bonded by, for example, anodic bonding.

Next, the operation of the physical quantity sensor 100 will be described.
In the physical quantity sensor 100, the movable unit 20 swings around the support axis Q according to physical quantities such as acceleration and angular velocity. As the movable portion 20 moves, the distance between the first movable electrode 21 and the first fixed electrode 50 and the distance between the second movable electrode 22 and the second fixed electrode 52 change. Specifically, for example, when vertical upward (+ Z-axis direction) acceleration is applied to the physical quantity sensor 100, the movable portion 20 rotates counterclockwise, and the distance between the first movable electrode 21 and the first fixed electrode 50 is increased. Decreases, and the distance between the second movable electrode 22 and the second fixed electrode 52 increases. As a result, the capacitance C1 increases and the capacitance C2 decreases. Further, for example, when vertical downward acceleration (−Z axis direction) is applied to the physical quantity sensor 100, the movable portion 20 rotates clockwise, and the distance between the first movable electrode 21 and the first fixed electrode 50 increases. The distance between the second movable electrode 22 and the second fixed electrode 52 is reduced. As a result, the capacitance C1 is reduced and the capacitance C2 is increased.

  In the physical quantity sensor 100, the capacitance C <b> 1 is detected using the pads 70 and 72, and the capacitance C <b> 2 is detected using the pads 70 and 74. Then, based on the difference between the capacitance C1 and the capacitance C2 (by a so-called differential detection method), it is possible to detect a physical quantity such as the direction and size such as acceleration and angular velocity.

  As described above, the physical quantity sensor 100 can be used as an inertial sensor such as an acceleration sensor or a gyro sensor. Specifically, for example, a capacitance for measuring acceleration in the vertical direction (Z-axis direction). It can be used as a type acceleration sensor.

  In the physical quantity sensor 100 described above, the separation distance between the first fixed electrode 50 and the first dummy electrode 53 and the second dummy electrode 54 and the separation distance between the second fixed electrode 52 and the first dummy electrode 53 and the third dummy electrode 55. The fixed electrodes 50 and 52 and the dummy electrodes 53, 54, and 55 are arranged so that the capacitance offset is smaller than the capacitance offset when the distance is equal.

  With such a configuration, it is possible to prevent the occurrence of sticking and reduce the capacity offset.

  More specifically, for example, the distance between the first fixed electrode 50 and the first dummy electrode 53 is w1, the distance between the second fixed electrode 52 and the first dummy electrode 53 is w2, and the first fixed electrode 50 is When the separation distance from the second dummy electrode 54 is w3 and the separation distance between the second fixed electrode 52 and the third dummy electrode 55 is w4, the relationship of w1 <w2 and w3 = w4 is satisfied.

  With this configuration, the capacitance C4 between the first fixed electrode 50 and the first dummy electrode 53, the capacitance C5 between the second fixed electrode 52 and the first dummy electrode 53, the first When the capacitance C6 between the first fixed electrode 50 and the second dummy electrode 54 and the capacitance C7 between the second fixed electrode 52 and the third dummy electrode 55 are set, C4 = C5 and C6> C7. The capacity offset can be further reduced.

  Further, for example, by configuring w1 <w2 and w3 = w4, even if C6 <C7, the capacitance offset can be further reduced by satisfying C4> C5.

  Further, for example, by configuring so that w1 <w2 and w3 <w4, C4> C5 and C6> C7, and the capacitance offset can be further reduced.

  Further, for example, when w1 is narrowed, by configuring so that w1 <w2, w3> w4, C4 >> C5 and C6 <C7, and the capacitance offset can be further reduced.

  Further, for example, when w3 is narrowed, by configuring so that w1> w2, w3 <w4, C4 <C5, C6 >> C7, and the capacitance offset can be further reduced.

  Further, in the physical quantity sensor 100 configured as described above, since the dummy electrodes 53, 54, and 55 are not formed in the sensor area (area where the capacitance changes), there is a risk that the accuracy may be reduced due to the occurrence of measurement variations or the like. Absent.

[Method of manufacturing physical quantity sensor]
Next, a method for manufacturing the physical quantity sensor of FIG. 1 will be described with reference to the drawings. 5 to 7 are cross-sectional views schematically showing the manufacturing process of the physical quantity sensor 100 of FIG. 1 and correspond to FIG.

  As shown in FIG. 5, for example, a glass substrate is patterned to form a recess 11, a post portion 13 in which a recess portion 15 is formed, and groove portions 17, 18, and 19 (see FIG. 1). The patterning is performed by, for example, photolithography and etching. By this step, the substrate 10 on which the concave portion 11, the post portion 13, and the groove portions 17, 18, and 19 are formed can be obtained.

  Next, fixed electrodes 50 and 52 and dummy electrodes 53, 54 and 55 are formed on the bottom surface 12 of the recess 11. Next, the wiring layer portion 61 and the wirings 64 and 66 are formed on the substrate 10 (see FIG. 1). The wirings 64 and 66 are formed so as to be connected to the fixed electrodes 50 and 52, respectively. Next, the bump part 62 is formed on the wiring layer part 61 (see FIGS. 3 and 4). Thereby, the first wiring 60 can be formed. The bump part 62 is formed so that its upper surface is located above the upper surface 14 of the post part 13. Next, pads 70, 72, and 74 are formed so as to be connected to the wirings 60, 64, and 66, respectively (see FIG. 1).

  The fixed electrodes 50 and 52, the wirings 60, 64, and 66, and the pads 70, 72, and 74 are formed by, for example, film formation by sputtering or CVD (Chemical Vapor Deposition) and patterning. The patterning is performed by, for example, photolithography and etching.

  As shown in FIG. 6, for example, a silicon substrate 102 is bonded to the substrate 10. The bonding between the substrate 10 and the silicon substrate 102 is performed by, for example, anodic bonding. Thereby, the board | substrate 10 and the silicon substrate 102 can be joined firmly. When the silicon substrate 102 is bonded to the substrate 10, the silicon substrate 102 is depressed by, for example, the bump portion 62 of the first wiring 60 (see FIGS. 3 and 4). As a result, stress is generated in the silicon substrate 102.

  As shown in FIG. 7, the silicon substrate 102 is ground by, for example, a grinding machine to form a thin film, and then patterned into a predetermined shape so that the movable unit 20, the coupling units 30 and 32, and the support unit 40 are integrated. Form. The patterning is performed by photolithography and etching (dry etching), and a Bosch method can be used as a more specific etching technique.

As shown in FIG. 2, the lid 80 is bonded to the substrate 10, and the movable portion 20 and the like are accommodated in the cavity 82 formed by the substrate 10 and the lid 80. The bonding between the substrate 10 and the lid 80 is performed by, for example, anodic bonding. Thereby, the board | substrate 10 and the cover body 80 can be joined firmly. By performing this step in an inert gas atmosphere, the cavity 82 can be filled with an inert gas.
Through the above steps, the physical quantity sensor 100 can be manufactured.

[Modification of physical quantity sensor]
Next, a physical quantity sensor according to a modification of the physical quantity sensor 100 will be described with reference to the drawings. FIG. 8 is a plan view schematically showing a physical quantity sensor 200 according to a modification. For the sake of convenience, FIG. 8 shows the lid 80 in a perspective view. Further, in FIG. 8, an X axis, a Y axis, and a Z axis are illustrated as three axes orthogonal to each other.

  Hereinafter, in the physical quantity sensor 200 according to the modification, members having the same functions as those of the constituent members of the physical quantity sensor 100 in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the physical quantity sensor 100, as shown in FIG. 1, the planar shape of the support portion 40 is H-shaped (substantially H-shaped). On the other hand, in the physical quantity sensor 200, as shown in FIG. 8, the planar shape of the support part 40 is a quadrangle (in the illustrated example, a rectangle).

  In the physical quantity sensor 200, the contact region 63 is 1 on one side (specifically on the + X axis direction side) and on the other side (specifically on the −X axis direction side) with the support axis Q as a boundary in plan view. It is provided one by one.

  Similar to the physical quantity sensor 100, the physical quantity sensor 200 can have high reliability.

[Electronics]
Next, the electronic apparatus of the present invention will be described.

  FIG. 9 is a perspective view showing a configuration of a mobile (or notebook) personal computer to which the electronic apparatus of the present invention is applied.

  As shown in FIG. 9, the personal computer 1100 includes a main body portion 1104 having a keyboard 1102 and a display unit 1106 having a display portion 1108. The display unit 1106 has a hinge structure portion with respect to the main body portion 1104. It is supported so that rotation is possible.

  Such a personal computer 1100 incorporates a physical quantity sensor 100.

  FIG. 10 is a perspective view showing a configuration of a mobile phone (including PHS) to which the electronic apparatus of the invention is applied.

As shown in FIG. 10, the cellular phone 1200 includes a plurality of operation buttons 1202, an earpiece 1204, and a mouthpiece 1206, and a display unit 1208 is disposed between the operation buttons 1202 and the earpiece 1204. .
Such a cellular phone 1200 incorporates a physical quantity sensor 100.

  FIG. 11 is a perspective view showing the configuration of a digital still camera to which the electronic apparatus of the present invention is applied. In this figure, connection with an external device is also simply shown.

  Here, an ordinary camera sensitizes a silver halide photographic film with a light image of a subject, whereas a digital still camera 1300 photoelectrically converts a light image of a subject with an image sensor such as a CCD (Charge Coupled Device). An imaging signal (image signal) is generated.

  A display unit 1310 is provided on the back of a case (body) 1302 in the digital still camera 1300, and is configured to display based on an imaging signal from the CCD. The display unit 1310 displays an object as an electronic image. Functions as a viewfinder.

  A light receiving unit 1304 including an optical lens (imaging optical system), a CCD, and the like is provided on the front side (the back side in the drawing) of the case 1302.

  When the photographer confirms the subject image displayed on the display unit 1310 and presses the shutter button 1306, the CCD image pickup signal at that time is transferred and stored in the memory 1308.

  In the digital still camera 1300, a video signal output terminal 1312 and an input / output terminal 1314 for data communication are provided on the side surface of the case 1302. A television monitor 1430 is connected to the video signal output terminal 1312 and a personal computer 1440 is connected to the input / output terminal 1314 for data communication, if necessary. Further, the imaging signal stored in the memory 1308 is output to the television monitor 1430 or the personal computer 1440 by a predetermined operation.

  Such a digital still camera 1300 incorporates a physical quantity sensor 100.

  Since the electronic devices 1100, 1200, and 1300 as described above include the physical quantity sensor 100, they can have high reliability.

  In addition to the personal computer (mobile personal computer) shown in FIG. 9, the mobile phone shown in FIG. 10, the digital still camera shown in FIG. (For example, inkjet printers), laptop personal computers, televisions, video cameras, video tape recorders, various navigation devices, pagers, electronic notebooks (including those with communication functions), electronic dictionaries, calculators, electronic game devices, head mounted displays, Word processor, workstation, videophone, security TV monitor, electronic binoculars, POS terminal, medical equipment (eg electronic thermometer, blood pressure monitor, blood glucose meter, electrocardiogram measuring device, ultrasonic diagnostic device, electronic endoscope), fish finder , Seed measuring instruments, gauges (e.g., vehicles, aircraft, rockets, instruments and a ship), attitude control such as a robot or a human body, can be applied to a flight simulator.

[Moving object]
FIG. 12 is a perspective view showing a configuration of an automobile which is an example of the moving body of the present invention.

  The automobile 1500 has a physical quantity sensor 100 built therein. Specifically, as shown in FIG. 12, an electronic control unit (ECU) that controls the output of the engine by incorporating a physical quantity sensor 100 that detects the acceleration of the automobile 1500 into the body 1502 of the automobile 1500. 1504 is mounted. In addition, the physical quantity sensor 100 can be widely applied to a vehicle body attitude control unit, an anti-lock brake system (ABS), an air bag, and a tire pressure monitoring system (TPMS). .

  Since the automobile 1500 includes the physical quantity sensor 100, the automobile 1500 can have high reliability.

  The above-described embodiments and modifications are merely examples, and the present invention is not limited to these. For example, it is possible to appropriately combine each embodiment and each modification.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 2 ... Structure 10 ... Board | substrate 102 ... Silicon substrate 11 ... Recessed part 12 ... Bottom surface 13 ... Post part 14 ... Upper surface 15 ... Depression part 16 ... Bottom surface 17 ... 1st groove part 18 ... 2nd groove part 19 ... 3rd groove part 20 ... Movable part 20a ... 1st mass part 20b ... 2nd mass part 21 ... 1st movable electrode 22 ... 2nd movable electrode 23, 24 ... End surface 25 ... Through-hole 26 ... Opening part 30 ... 1st connection part 32 ... 2nd connection part 40 ... support part 41 ... first part 42 ... second part 43 ... second part 44 ... second part 45 ... second part 46 ... connection region 50 ... first fixed electrode 52 ... second fixed electrode 53 ... first dummy electrode 54 ... 2nd dummy electrode 55 ... 3rd dummy electrode 60 ... 1st wiring 61 ... Wiring layer part 62 ... Bump part 63 ... Contact area 64 ... 2nd wiring 66 ... 3rd wiring 70 ... 1st pad 72 ... 2nd pad 74 ... Third pad 80 ... lid body 82 ... cavity 100, 200 ... physical quantity sensor 1100 ... personal computer 1102 ... keyboard 1104 ... main body 1106 ... display unit 1108 ... display unit 1200 ... mobile phone 1202 ... operation button 1204 ... earpiece 1206 ... mouthpiece 1208 ... Display unit 1300 ... Digital still camera 1302 ... Case 1304 ... Light receiving unit 1306 ... Shutter button 1308 ... Memory 1310 ... Display unit 1312 ... Video signal output terminal 1314 ... Input / output terminal 1430 ... TV monitor 1440 ... Personal computer 1500 ... Automobile 1502 ... Body 1504 ... Electronic control unit Q ... Support shaft R ... Second shaft

Claims (8)

A substrate,
A support fixed to the substrate;
A movable part connected to the support part via a connecting part and swingable relative to the support part;
A fixed electrode disposed on the substrate so as to face the movable part,
The movable part is arranged on the first mass part provided on one side with respect to the connecting part, a second mass part provided on the other side and having a mass larger than the first mass part, and the first mass part. A first movable electrode, and a second movable electrode disposed on the second mass part,
The fixed electrode is opposed to the first fixed part, the first fixed electrode disposed opposite to the first mass part, the second fixed electrode disposed opposite to the second mass part, the movable part, and A dummy electrode disposed so as not to contact the first fixed electrode and the second fixed electrode, and having the same potential as the movable part,
The dummy electrode includes a first dummy electrode provided between the first fixed electrode and the second fixed electrode, and a second dummy electrode provided on the opposite side of the first fixed electrode from the first dummy electrode. A dummy electrode, and a third dummy electrode provided on the opposite side of the second fixed electrode from the first dummy electrode,
Capacitance when the separation distance between the first fixed electrode and the first dummy electrode and the second dummy electrode is equal to the separation distance between the second fixed electrode and the first dummy electrode and the third dummy electrode The physical quantity sensor, wherein the fixed electrode and the dummy electrode are arranged so that a capacitance offset is smaller than an offset.   The separation distance between the first fixed electrode and the first dummy electrode is w1, the separation distance between the second fixed electrode and the first dummy electrode is w2, and the separation between the first fixed electrode and the second dummy electrode. 2. The physical quantity sensor according to claim 1, wherein a relationship of w <b> 1 <w <b> 2 and w <b> 3 = w <b> 4 is satisfied, where a distance is w <b> 3 and a separation distance between the second fixed electrode and the third dummy electrode is w <b> 4.   The separation distance between the first fixed electrode and the first dummy electrode is w1, the separation distance between the second fixed electrode and the first dummy electrode is w2, and the separation between the first fixed electrode and the second dummy electrode. 2. The physical quantity sensor according to claim 1, wherein a relationship of w <b> 1 <w <b> 2 and w <b> 3 <w <b> 4 is satisfied, where w <b> 3 is a distance and w <b> 4 is a separation distance between the second fixed electrode and the third dummy electrode.   The separation distance between the first fixed electrode and the first dummy electrode is w1, the separation distance between the second fixed electrode and the first dummy electrode is w2, and the separation between the first fixed electrode and the second dummy electrode. 2. The physical quantity sensor according to claim 1, wherein a relationship of w <b> 1 <w <b> 2, w <b> 3> w <b> 4 is satisfied, where a distance is w <b> 3 and a separation distance between the second fixed electrode and the third dummy electrode is w <b> 4.   The separation distance between the first fixed electrode and the first dummy electrode is w1, the separation distance between the second fixed electrode and the first dummy electrode is w2, and the separation between the first fixed electrode and the second dummy electrode. 2. The physical quantity sensor according to claim 1, wherein a relationship of w <b> 1> w <b> 2 and w <b> 3 <w <b> 4 is satisfied, where a distance is w <b> 3 and a separation distance between the second fixed electrode and the third dummy electrode is w <b> 4.   The physical quantity sensor according to claim 1, wherein the substrate is a glass substrate.   An electronic apparatus comprising the physical quantity sensor according to claim 1.   A moving body comprising the physical quantity sensor according to claim 1.

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