JP5850195B2 - Functional element - Google Patents

Description

  The present invention relates to a functional element.

  As the functional element, there is a fixed electrode that is fixedly arranged, and a movable electrode that is disposed so as to be displaceable and opposed to the fixed electrode, and a capacitance between the fixed electrode and the movable electrode Based on the above, there are known physical quantity sensor elements that detect physical quantities such as acceleration and angular velocity (see Patent Document 1 and Patent Document 2).

  The physical quantity sensor elements of Patent Document 1 and Patent Document 2 have a structure in which each comb electrode portion is mechanically connected while being electrically insulated by a groove filled with an insulating material so that capacitance can be detected by a differential method. have.

  For example, the physical quantity sensor element described in Patent Document 1 uses a single-layer semiconductor substrate or an SOI substrate, and the fixed electrode and the movable electrode each have a plurality of electrode fingers arranged in a comb-teeth shape. They are arranged to engage.

  Moreover, in the physical quantity sensor element described in Patent Document 1, two electrode fingers of the fixed electrode are provided between two adjacent electrode fingers of the movable electrode, and the two electrode fingers of the fixed electrode are provided. Are electrically isolated from each other. Thereby, the electrostatic capacitance between the other electrode finger of the one electrode finger of the two electrode fingers of the fixed electrode and the electrode finger of the movable electrode opposed thereto is measured separately, and based on the measurement results (Using a so-called differential detection method), the physical quantity can be detected.

  Further, in Patent Document 1 and Patent Document 2, a physical quantity sensor element is formed by processing a cavity under a movable structure by dry etching or the like on a single layer semiconductor substrate. When such a method is used, a sensor structure including an insulating separation structure can be formed using only a single layer substrate, and low cost can be realized.

Japanese Patent No. 4238437 Japanese translation of PCT publication No. 2002-510139

  However, in Patent Document 1 and Patent Document 2, since the movable structure that is insulated and separated in the single-layer semiconductor substrate is floated by dry etching or the like, there are restrictions on the thickness and shape of the movable structure, and high sensitivity and There was a problem in terms of impact resistance.

  In particular, the physical quantity sensor element described in Patent Document 1 has a problem in that it is necessary to individually isolate and separate the electrode fingers so that each of the fixed electrode and the movable electrode does not conduct, and manufacturing efficiency decreases. Furthermore, the SOI substrate is generally expensive, and there is a problem that the product cost increases.

  Accordingly, the present invention focuses on the above-described problems and aims to provide a functional element that suppresses a decrease in manufacturing efficiency.

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.
A functional element according to a first aspect includes a first substrate and a first fixed electrode provided on one side of the first substrate, and the space between the first substrate and the first fixed electrode. Is provided with an internal space, and the first board is provided with a first wiring groove and a first wiring groove that communicates the internal space and the outside. The first fixed electrode is disposed so as to overlap at least a part of the first wiring groove, and the first fixed electrode is electrically connected to the first wiring provided in the first wiring groove. It is characterized by being connected to.
The functional element according to a second aspect is the functional element according to the first aspect, wherein the functional element includes a conductive layer between the first fixed electrode and the first wiring, and the first fixed electrode and the first wiring Are electrically connected to each other.
The functional element according to a third aspect is the functional element according to the first aspect or the second aspect, wherein the second fixed electrode is spaced from the first fixed electrode, and the first fixed electrode And a movable electrode provided between the second fixed electrode, and a second wiring groove having a second wiring arranged on the first substrate and communicating with the outside The second fixed electrode is disposed so as to overlap at least part of the second wiring groove in a plan view of the first substrate, and the second fixed electrode is disposed in the second wiring groove. It is electrically connected to the second wiring provided.
The functional element according to a fourth aspect is the functional element according to the second aspect or the third aspect, wherein the second fixed electrode is disposed so as to straddle the first wiring groove, and the first fixed electrode is The second wiring is electrically connected to the first wiring and insulated from the second wiring, and the second fixed electrode is electrically connected to the second wiring and the first wiring. It is characterized by being insulated from the wiring.
A functional element according to a fifth aspect is a lid provided to cover the first fixed electrode and the second fixed electrode in the functional element according to any one of the first to fourth aspects. The outside is outside the portion covered with the lid.

  [Application Example 1] A first substrate and a second substrate provided on the first substrate and having an element portion, and an internal space is provided between the first substrate and the second substrate. A functional element is provided, wherein at least one of the opposing surfaces of the first substrate and the second substrate is provided with a groove communicating the internal space with the outside.

  In the above configuration, for example, when the element portion is formed on the second substrate after laminating the second substrate on the first substrate, a gas due to bonding may be generated when the first substrate and the second substrate are bonded. May be adversely affected on the formation of the element portion. However, by forming a groove that connects the outside and the internal space on at least one surface of the first substrate and the second substrate before stacking, the gas passes from the internal space through the vent hole during stacking. Since it can be discharged to the outside, the manufacturing yield of the element portion can be increased. Further, it is not necessary to form the ventilation holes independently, and the ventilation holes can be easily formed by forming grooves on the surface of the substrate and laminating them.

Application Example 2 According to Application Example 1, wherein a lid is bonded to the first substrate with an adhesive member so as to cover the second substrate, and the groove is sealed with the adhesive member. The functional element described.
With the above configuration, since the groove can be sealed with the lid adhesive member while the second substrate is sealed with the lid, the manufacturing efficiency is remarkably improved.

Application Example 3 The functional element according to Application Example 1 or 2, wherein the groove is provided with wiring of the element portion.
With the above configuration, the groove can be used not only for degassing the internal space but also as a wiring path for the element portion.

Application Example 4 The first substrate is formed of glass, the second substrate is formed of a semiconductor material, and the first substrate and the second substrate are bonded by anodic bonding. The functional element as described in any one of Application Examples 1 to 3.
With the above configuration, the first substrate and the second substrate can be firmly connected by anodic bonding without using an adhesive. In addition, gas is generated and released into the internal space at the time of anodic bonding, but the gas can be discharged to the outside through the vent hole, and the yield of manufacturing the movable part can be increased.

Application Example 5 The element unit includes a movable part, a support part that supports the movable part, and a fixed electrode finger that is connected to the first substrate side, and the movable part includes the fixed electrode finger. The functional element according to any one of Application Examples 1 to 4, further comprising: a movable electrode finger facing the flexible electrode; and a flexible part connecting the movable electrode finger and the support part.
With the above configuration, for example, when an external force is applied, the capacitance between the movable electrode finger and the fixed electrode finger changes due to the displacement of the movable electrode finger. Therefore, a physical quantity such as acceleration can be detected by the change in capacitance, and a sensor with excellent manufacturing efficiency can be realized.

Application Example 6 Preparing a first substrate and a second substrate, forming a groove on a surface of at least one of the first substrate and the second substrate, and forming the second substrate on the first substrate Bonding, forming an internal space between the first substrate and the second substrate, venting the internal space by the groove, forming an element portion on the second substrate, and the second And a step of bonding a lid on the first substrate with an adhesive member so as to cover the substrate, and sealing the groove with the adhesive member.
According to the above method, when the first substrate and the second substrate are stacked, the gas can be discharged from the internal space to the outside through the vent formed by the groove, so that the manufacturing yield of the element portion is increased. Can do.

  Application Example 7 Preparing a first substrate and a second substrate, forming a through hole in the second substrate, joining the second substrate on the first substrate, and connecting the first substrate and the second substrate Forming an internal space between the second substrate and venting the internal space by the through hole; and forming an element portion by etching a region including the through hole of the second substrate; A method for manufacturing a functional element, comprising:

  According to the above method, the gas can be discharged from the internal space through the through hole to the outside during the stacking, so that the yield of manufacturing the element portion can be increased. Furthermore, since the through hole penetrating into the internal space is formed in the region where the second substrate is etched, the through hole can be eliminated when forming the element portion, and it is not necessary to seal the through hole. Manufacturing efficiency is improved.

[Application Example 8] A physical quantity sensor comprising the functional element according to any one of Application Examples 1 to 5.
With the above configuration, a physical quantity sensor with excellent manufacturing efficiency can be provided.

Application Example 9 An electronic apparatus comprising the functional element according to any one of Application Examples 1 to 8.
With the above configuration, an electronic device having excellent manufacturing efficiency can be provided.

It is a top view of the functional element concerning a 1st embodiment. It is an enlarged view of the part enclosed with the dashed-dotted line of FIG. It is the sectional view on the AA line of FIG. It is the BB sectional view taken on the line of FIG. It is CC sectional view taken on the line of FIG. It is the DD sectional view taken on the line of FIG. The manufacturing process of the functional element of 1st Embodiment is shown. Here, in FIGS. 7A to 7E, the left side shows the manufacturing process of the part surrounded by the one-dot chain line in FIG. 5, and the center shows the manufacturing process of the part surrounded by the one-dot chain line in FIG. The right side shows the manufacturing process of the part surrounded by the one-dot chain line in FIG. It is a figure which shows the functional element which concerns on 2nd Embodiment. The functional element which concerns on 3rd Embodiment is shown, Fig.9 (a) is a partial top view, FIG.9 (b) is a partial side view. The functional element which concerns on 4th Embodiment is shown, FIG.10 (a) is a fragmentary top view before forming a movable part etc. in a 2nd board | substrate, FIG.10 (b) is the sectional view on the AA line of Fig.10 (a). FIG. 10 (c) is a partial plan view after a movable part and the like are formed on the second substrate. It is a figure which shows the functional element which concerns on 5th Embodiment. The functional element which concerns on 6th Embodiment is shown, Fig.12 (a) is a top view, FIG.12 (b) is the schematic diagram seen from the side surface. It is a figure which shows the functional element which concerns on 7th Embodiment.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .

  1 to 6 show a functional element according to the first embodiment. Here, FIG. 1 is a plan view of the functional element according to the first embodiment, FIG. 2 is an enlarged view of a portion surrounded by a one-dot chain line in FIG. 1, FIG. 3 is a sectional view taken along line AA in FIG. 1 is a cross-sectional view taken along line BB in FIG. 1, FIG. 5 is a cross-sectional view taken along line CC in FIG. 1, and FIG. 6 is a cross-sectional view taken along line DD in FIG.

The functional element 10 of the present embodiment has a configuration in which a second substrate 50 is stacked on a first substrate 12 serving as an insulator, and the second substrate 50 is sealed with a lid 66.
For example, the first substrate 12 is formed of an insulator such as glass, and the second substrate 50 is formed of a semiconductor substrate such as silicon. On the second substrate 50 side of the first substrate 12, a recess 20, an exhaust groove 24 serving as a first groove, a first wiring groove 26 serving as a second groove, and a second wiring groove 28 are formed. Furthermore, a third wiring groove 30 is formed in the first substrate 12 in addition to the first wiring groove 26 and the second wiring groove 28.

  Further, the first substrate 12 includes a bonding portion 14 that is bonded to the second substrate 50, an outer peripheral portion 16 that surrounds the periphery of the bonding portion 14, and a terminal portion 18 that is connected to the outer peripheral portion 16. The joining portion 14 is a region overlapping the second substrate 50 in plan view, and the outer peripheral portion 16 is a region surrounding the joining portion 14 and overlapping the lid 66 in plan view.

  The concave portion 20 is for avoiding interference between the movable portion 54 constituting the element portion described later and the first substrate 12. Therefore, the concave portion is formed in the joint portion 14 at a position facing the movable portion 54. Further, when the second substrate 50 is laminated on the first substrate 12, an internal space 68 having the first substrate 12 as a part of the inner wall is formed by the recess 20.

  The exhaust groove 24 is for exhausting gas generated when the first substrate 12 is laminated (adhered) to the second substrate 50 to the outside. The exhaust groove 24 cuts out a part of the inner wall of the recess 20 and communicates with the outside via the joint portion 14 and the outer peripheral portion 16. Therefore, an exhaust hole 70 communicating from the internal space 68 to the outside of the joint portion 14 is formed by the exhaust groove 24.

  The first wiring groove 26 is a groove for arranging the first wiring 32 electrically connected to the second substrate 50, and the second wiring groove 28 is the first wiring electrically connected to the second substrate 50. This is a groove for arranging a second wiring 38 different from the groove 26. The first wiring groove 26 and the second wiring groove 28 extend from the region which is the bonding portion 14 of the first substrate 12 outside the concave portion 20 to the terminal portion 18 via the outer peripheral portion 16 and again to the outer peripheral portion 16 and the bonding. It is formed in a U shape that returns to the portion 14. The second wiring groove 28 is formed along the inside of the first wiring groove 26. Further, in the joint portion 14, the first wiring groove 26 and the second wiring groove 28 are under fixed electrode fingers (a first fixed electrode finger 62 and a second fixed electrode finger 64) described later configured using the second substrate 50. Pass through. Note that a gap is formed between the first wiring groove 26 and the second wiring groove 28 and a support portion 52 (described later) configured using the second substrate 50, and each wiring groove is formed of an insulating material or the like as described later. Each wiring groove in the joint portion 14 functions as an exhaust hole 72 unless filled with.

  The third wiring groove 30 is a groove for arranging the third wiring 44 for electrical connection with the second substrate 50. The third wiring groove 30 passes under the support portion 52 and is led out to the terminal portion 18 via the outer peripheral portion 16.

  Specifically, it is preferable to use a high-resistance silicon material or glass material as the constituent material of the first substrate 12. In particular, when the second substrate described later is composed mainly of a silicon material, alkali metal ions are used. It is preferable to use a glass material containing (movable ions) (for example, a borosilicate glass such as Pyrex (registered trademark)). By this. When the second substrate 50 is composed of silicon as a main material, the first substrate 12 and the second substrate 50 can be anodically bonded. By this anodic bonding, the first substrate 12 and the second substrate 50 can be firmly connected without using an adhesive.

  Further, the constituent material of the first substrate 12 is preferably such that the difference in thermal expansion coefficient between the constituent materials of the second substrate 50 is as small as possible. Specifically, the constituent material of the first substrate 12 and the constituent material of the second substrate 50 ( And the difference in thermal expansion coefficient from the constituent material of the lid) is preferably 3 ppm / ° C. or less. Accordingly, even if the first substrate 12 and the second substrate 50 are exposed to a high temperature during bonding, the residual stress between the first substrate 12 and the second substrate 50 can be reduced.

  The first wiring 32 is formed in the first wiring groove 26 as a wiring of an element portion to be described later, and is electrically connected to the first fixed electrode finger 62 constituting the fixed electrode finger. In addition, the second wiring 38 is formed in the second wiring groove 28 as a wiring of an element portion to be described later, and is electrically connected to the second fixed electrode finger 64 constituting the fixed electrode finger. Therefore, the first bump 34 serving as a protrusion is provided at a position facing the first fixed electrode finger 62 of the first wiring 32, and the protrusion is disposed at a position facing the second fixed electrode finger 64 of the second wiring 38. The second bump 40 is provided. A first terminal electrode 36 is provided on the terminal portion 18 side of the first wiring 32, and a second terminal electrode 42 is provided on the terminal portion 18 side of the second wiring 38.

  The third wiring 44 is formed in the third wiring groove 30 as a wiring of an element section to be described later, and is electrically connected to a supporting section 52 (movable electrode finger 58) to be described later configured using the second substrate 50. To connect. Therefore, a third bump 46 serving as a protrusion is provided at a position facing the support portion 52 of the third wiring 44, and a third terminal electrode 48 is provided on the terminal portion 18 side of the third wiring 44.

  The thickness dimensions of the first wiring 32, the second wiring 38, and the third wiring 44 are formed to be smaller than the depth dimensions of the first wiring groove 26, the second wiring groove 28, and the third wiring groove 30, respectively. ing. The first bump 34, the second bump 40, and the third bump 46 are formed so as to protrude from the first wiring groove 26, the second wiring groove 28, and the third wiring groove 30 onto the main surface of the first substrate 12, respectively. . Each bump is crushed when the second substrate 50 is stacked on the first substrate 12. As a result, the first wiring 32 is electrically and mechanically connected to a first fixed electrode finger 62 described later, and the second wiring 38 is electrically and mechanically connected to a second fixed electrode finger 64 described later. The third wiring 44 is electrically and mechanically connected to a support portion 52 (movable electrode finger 58) described later.

  Further, the first wiring groove 26, the second wiring groove 28, and the third wiring groove 30 are respectively a first bump 34, a first terminal electrode 36, a second bump 40, a second terminal electrode 42, a third bump 46, and a third bump. The terminal electrode 48 may be exposed and embedded with an insulating resin material or the like.

  The constituent materials of the first wiring 32, the second wiring 38, and the third wiring 44 are not particularly limited as long as they have conductivity, and various electrode materials can be used. For example, ITO (Indim Tin Oxide), IZO (Indium Zinc Oxide), In3O3, SnO2, Sb-containing SnO2, oxides (transparent electrode materials) such as Al-containing ZnO, Au, Pt, Ag, Cu, Al or alloys containing these. These can be used alone or in combination of two or more.

  Among these, it is preferable to use a transparent electrode material (especially ITO) as a constituent material of each of the above-mentioned wirings. When each wiring is made of a transparent conductive material, when the first substrate 12 is transparent, fixed electrode fingers (first fixed electrode fingers 62, second fixed electrode fingers 64) constituting the second substrate 50 are used. It is possible to easily see foreign matter or the like existing on the surface of the first substrate 12 from the surface opposite to the fixed electrode finger of the first substrate 12, and the functional element 10 can be easily inspected.

  In addition, the constituent materials of the first terminal electrode 36, the second terminal electrode 42, and the third terminal electrode 48 are not particularly limited as long as they have conductivity similar to the above-described wirings, and various electrode materials are used. Can do.

  Further, the constituent materials of the first bump 34, the second bump 40, and the third bump 46 are not particularly limited as long as they have conductivity, and various electrode materials can be used. A single metal such as Au, Pt, Ag, Cu, Al, or an alloy metal containing these is suitable. By configuring each bump using such a metal, the contact resistance between each of the above-described wirings, the fixed electrode finger (first fixed electrode finger 62, second fixed electrode finger 64), and the movable electrode finger 58 is reduced. Can be small.

  The second substrate 50 detects physical quantities such as acceleration in the functional element 10. The second substrate 50 has an element part including a support part 52, a movable part 54, a first fixed electrode finger 62, and a second fixed electrode finger 64. Here, it is preferable to use a conductive substrate for the second substrate 50, and the support portion 52 and the movable portion 54 are in an electrically connected state. On the other hand, the first fixed electrode finger 62 and the second fixed electrode finger 64 are spatially separated from the support portion 52 and the movable portion 54 and are electrically insulated. Therefore, the second substrate 50 has the cavity portion 74 between the support portion 52, the movable portion 54, the first fixed electrode finger 62, and the second fixed electrode finger 64.

  The support part 52 is bonded to the first substrate 12 and supports the movable part 54. The support portion is electrically connected to the third wiring and the third terminal electrode by connecting the third bump. The support 52 forms a gap with the exhaust groove 24 by stacking the second substrate 50 on the first substrate 12. As a result, an exhaust hole 70 communicating from the internal space 68 to the outside of the joint portion 14 of the first substrate 12 is formed.

  The movable part 54 is displaced in the direction of the arrow in FIG. The movable portion 54 is formed at a position facing the concave portion 20 formed in the first substrate 12, and the movable portion 54 is prevented from joining and interference with the first substrate 12, and is movable by an external force (for example, acceleration) received from the outside. . The movable portion 54 includes a beam 56 whose longitudinal direction is the arrow direction in FIG. 1, a flexible portion 60 connected to both ends of the beam 56 in the longitudinal direction and connected to the support portion 52, and perpendicular to the longitudinal direction of the beam 56. A plurality of movable electrode fingers 58 connected to the beam 56 in a state of being arranged at a constant interval so as to extend in the direction. For example, when the movable portion 54 as a whole receives acceleration in the direction of the arrow in the drawing, the flexible portion 60 bends and deforms in the direction of the arrow in the drawing. Therefore, the beam 56 is displaced in the longitudinal direction of the beam 56 by the acceleration. As a result, the movable electrode finger 58 connected to the beam 56 is also displaced in the longitudinal direction of the beam 56.

  The first fixed electrode finger 62 and the second fixed electrode finger 64 are formed spatially separated from the support portion 52 and the movable portion 54 as described above, and one end in the longitudinal direction of the fixed electrode finger is the first substrate. 12 are joined at positions facing the first wiring 32 and the second wiring 38 of the joining portion 14, and the other end in the longitudinal direction of the fixed electrode finger is disposed at a position facing the recess 20 of the first substrate 12. In addition, the first fixed electrode fingers 62 and the second fixed electrode fingers 64 are alternately arranged in the direction of the arrow in the drawing at regular intervals. Further, a movable electrode finger 58 is disposed between the first fixed electrode finger 62 and the second fixed electrode finger 64 so as to intersect from the direction perpendicular to the direction of the arrow in the drawing. Therefore, the movable electrode finger 58 is opposed to the first fixed electrode finger 62 at a certain interval on one surface in the direction of the arrow in the figure, and at a certain interval from the second fixed electrode finger 64 on the other surface. Will face each other. Therefore, a comb-like fixed electrode is formed by the arrangement of the first fixed electrode finger 62 and the second fixed electrode finger 64, and the comb-like shape is formed by the movable electrode finger 58 disposed so as to bite the comb-like fixed electrode. The movable electrode is formed.

  Further, the first fixed electrode finger 62 is electrically connected to the first bump 34, and the second fixed electrode finger 64 is electrically connected to the second bump 40. Therefore, the first fixed electrode finger 62 is electrically connected to the first terminal electrode 36, and the second fixed electrode finger 64 is electrically connected to the second terminal electrode 42. The movable electrode finger 58 is electrically connected to the support portion 52 via the beam 56 and the flexible portion 60. Therefore, the movable electrode finger 58 is electrically connected to the third terminal electrode 48 via the support portion 52. Therefore, when a voltage is applied to the third terminal electrode 48, a capacitance is generated between the movable electrode finger 58 and the first fixed electrode finger 62, and a static electricity is generated between the movable electrode finger 58 and the second fixed electrode finger 64. Electric capacity is generated. Therefore, information on the capacitance between the movable electrode finger 58 and the first fixed electrode finger 62 can be obtained from the first terminal electrode 36. Capacitance information between the movable electrode finger 58 and the second fixed electrode finger 64 can be obtained from the second terminal electrode 42.

  Here, when the movable portion 54 is displaced in the direction of the arrow in the drawing, the movable electrode finger 58 is biased to one of the first fixed electrode finger 62 and the second fixed electrode finger 64. At this time, the capacitance between the fixed electrode finger that is closer to the movable electrode finger 58 and the movable electrode finger 58 is increased, and between the fixed electrode finger that is farther away from the movable electrode finger 58 and the movable electrode finger 58. The capacitance of decreases.

  Therefore, in this embodiment, the electrostatic capacitance between the movable electrode finger 58 and the first fixed electrode finger 62 and the electrostatic capacitance between the movable electrode finger 58 and the second fixed electrode finger 64 are independently measured. Further, by measuring the difference, the magnitude of the physical quantity measured and the direction thereof (direction of the arrow in the figure) can be detected with high accuracy.

  Here, the constituent materials of the second substrate 50, that is, the support portion 52, the movable portion 54 (the beam 56, the movable electrode finger 58, the flexible portion 60), the first fixed electrode finger 62, and the second fixed electrode finger 64 will be described later. Thus, it is preferable to form by etching. As described above, the concave portion 20 is formed at a position facing the movable portion 54 of the first substrate 12. Therefore, in the second substrate 50, it is not necessary to form a recess for avoiding the joining and interference between the movable portion 54 and the first substrate 12, and each constituent material has the thickness of the second substrate 50 prepared in advance. It can be formed in a state. Therefore, the thickness of each constituent material can be easily and accurately aligned. Moreover, since each constituent material can be formed thick, the impact resistance of the functional element 10 can be improved. Furthermore, since the movable electrode finger 58, the first fixed electrode finger 62, and the second fixed electrode finger 64 can be formed thick, the capacitance between the electrodes can be increased, and the physical quantity detection sensitivity of the functional element 10 can be increased. Can be increased. Further, the first fixed electrode finger 62 and the second fixed electrode finger 64 are spatially separated from the support portion 52 and the movable portion 54. Thereby, it is possible to reduce the size of each fixed electrode finger while ensuring a sufficient bonding area between each fixed electrode finger and the first substrate 12. Therefore, it is possible to achieve both improvement in impact resistance and downsizing of the functional element 10.

  The constituent material of the second substrate 50 is not particularly limited as long as it can detect a physical quantity based on a change in capacitance as described above, but is preferably a semiconductor. Specifically, for example, single crystal silicon, polycrystal It is preferable to use a silicon material such as silicon.

  Silicon can be processed with high precision by etching. Therefore, by configuring the second substrate 50 using silicon as a main raw material, the dimensional accuracy of the second substrate 50 can be increased, and as a result, the sensitivity of the functional element 10 that is a physical quantity sensor element can be increased. In addition, since silicon is less fatigued, the durability of the functional element 10 can be improved. Further, it is preferable that the silicon material constituting the second substrate 50 is doped with impurities such as phosphorus and boron, whereby the conductivity of the second substrate 50 can be made excellent.

  The lid 66 has a cavity portion 76 in the shape of a cap, and is joined to the outer peripheral portion 16 of the first substrate 12 by, for example, an epoxy-based adhesive, and the second substrate 50 is accommodated in the cavity portion 76. The second substrate 50 is sealed. At that time, an adhesive layer 78 as an adhesive member between the lid 66 and the first substrate 12 enters the exhaust groove 24, the first wiring groove 26, the second wiring groove 28, and the third wiring groove 30, thereby causing the second. The substrate 50 is sealed.

  FIG. 7 shows a manufacturing process of the functional element of the first embodiment. Here, in FIGS. 7A to 7F, the left side shows the manufacturing process of the part surrounded by the one-dot chain line in FIG. 5, and the center shows the manufacturing process of the part surrounded by the one-dot chain line in FIG. The right side shows the manufacturing process of the part surrounded by the one-dot chain line in FIG.

  A manufacturing process of the functional element 10 according to the above configuration will be described. In the present embodiment, a case where a glass material is used as the constituent material of the first substrate 12 and silicon is used as the constituent material of the second substrate 50 will be described. First, as shown in FIG. 7A, the recess 20, the exhaust groove 24, the first wiring groove 26 (not shown), the second wiring groove 28, and the third wiring groove 30 are formed in the first substrate 12. These forming methods are not particularly limited, but for example, one or two of physical etching methods such as plasma etching, reactive ion etching, beam etching, and optically assisted etching, and chemical etching such as wet etching. A combination of the above can be used. Note that the same method can be used for etching in the following steps.

  In the above-described etching, for example, a mask formed by a photolithography method can be preferably used. Further, the mask formation, etching, and mask removal are repeated a plurality of times to form the recess 20, the exhaust groove 24, the first wiring groove 26, the second wiring groove 28, and the third wiring groove 30. This mask is removed after etching. As a method for removing the mask, for example, when the mask is formed of a resist material, a resist stripping solution is used. When the mask is formed of a metal material, a metal stripping solution such as a phosphoric acid solution is used. be able to. In addition, although the formation order of the recessed part 20, the exhaust groove 24, the 1st wiring groove 26, the 2nd wiring groove 28, and the 3rd wiring groove 30 can be set arbitrarily, a gray scale mask is used as a mask, for example. Thus, these (a plurality of recesses having different depths) may be formed collectively.

  Next, as shown in FIG. 7B, the first wiring 32 (not shown), the second wiring 38 and the third wiring 44 are formed on the first substrate 12. The method for forming each wiring (film forming method) is not particularly limited. For example, vacuum plating, sputtering (low temperature sputtering), dry plating methods such as ion plating, wet plating methods such as electrolytic plating and electroless plating, etc. For example, thin film bonding and the like. Note that the same method can be used for film formation in the following steps.

  Then, as shown in FIG. 7C, the first terminal electrode 36 (not shown), the second terminal electrode 42 (not shown), the third terminal electrode 48, the first bump 34 (not shown), the second bump 40, a third bump 46 is formed. In addition, after these are formed, an insulating material for protecting each wiring may be embedded in each groove in a state where these are exposed.

  Next, as shown in FIG. 7D, the bonding portion 14 on the upper surface of the first substrate 12 and the second substrate 50 before etching are bonded by an anodic bonding method. Thereby, an internal space is formed by the recess 20 and the second substrate 50. Also, by this bonding, each bump is crushed and is electrically and mechanically bonded to the corresponding movable electrode finger 58 and fixed electrode finger as described above.

  By the way, oxygen is generated from the bonding region between the first substrate 12 and the second substrate 50 by this anodic bonding and released into the internal space 68. However, since the exhaust hole 70 that connects the internal space 68 and the outside is formed by the second substrate 50 and the exhaust groove 24 during the anodic bonding, oxygen can be discharged from the internal space 68 to the outside. In addition, the second substrate 50 is for improving the handling sensitivity when being stacked on the first substrate 12 and increasing the detection sensitivity by increasing the aspect ratio (ratio of electrode width to electrode thickness) of the fixed electrode finger or the movable electrode finger. In addition, it may be thicker than necessary before bonding to the first substrate 12. At this time, the second substrate 50 after lamination is thinned using a CPM method, a dry polishing method, or the like.

  Then, as shown in FIG. 7E, the second substrate 50 is etched to form the cavity 74, and the support 52, the movable part 54 (the beam 56, the movable electrode finger 58, the flexible part 60). First fixed electrode fingers 62 and second fixed electrode fingers 64 are formed. At this time, the first fixed electrode finger 62 and the second fixed electrode finger 64 are spatially separated from each other and joined to the joint portion 14 of the first substrate 12 while being spatially separated from the support portion 52 and the movable portion. Maintain the state. Further, the first fixed electrode finger 62 is maintained in a state of being bonded to the first bump 34. The second fixed electrode finger 64 maintains a state where it is bonded to the second bump 40.

  Finally, as shown in FIG. 7F, the functional element 10 in which the lid 66 having the cavity portion 76 is bonded to the first substrate 12 and the second substrate 50 is accommodated and sealed is formed. Thus, since the 2nd board | substrate 50 is sealed with the lid 66, the movable part 54 can be operated stably. Further, when the exhaust hole 70 is formed by the exhaust groove 24 described above, the exhaust groove 24 can be sealed with an adhesive (adhesive layer 78) simultaneously with the sealing of the second substrate 50 by the lid 66. Manufacturing steps can be reduced and costs can be reduced.

  When the movable portion 54 is formed after laminating the second substrate 50 on the first substrate 12 as in the present embodiment, a gas due to bonding is generated when the first substrate 12 and the second substrate 50 are bonded. There is a possibility that the atmosphere inside the substrate expands, adversely affects the formation of the movable portion 54, and the first substrate 12 and the second substrate 50 are peeled off. However, by forming the exhaust hole 70 connecting the outside and the internal space 68 before stacking, gas can be discharged from the internal space 68 to the outside through the exhaust hole 70 during stacking. The manufacturing yield of the movable part 54 can be increased. Further, in the present embodiment, it is not necessary to form the exhaust holes 70 independently, and the exhaust holes 70 can be easily formed by forming grooves on the surface of the substrate (first substrate 12).

  FIG. 8 shows a functional element according to the second embodiment. In the following embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted unless necessary. The functional element 80 according to the second embodiment has a basic configuration similar to that of the first embodiment, but the first substrate 12 branches from the above-described second groove (second wiring groove 28) into the internal space 68. The difference is that a third groove (discharge groove 82) to be connected is provided.

  Therefore, when the second substrate 50 before etching is stacked on the first substrate 12, the second groove (second wiring groove 28) and the third groove (discharge groove 82) are replaced with the second groove (second groove). (2) The wiring groove 28) is sealed except for the end portion on the outer peripheral portion 16 side and the third groove (discharge groove 82) on the inner space 68 side. As a result, an exhaust hole 84 that communicates the internal space 68 with the outside of the second substrate 50 is formed.

Therefore, in the second embodiment, the second wiring groove 28 also has a function as a discharge groove.
Therefore, when protecting the second wiring 38 with an insulating material, it is necessary to prevent the groove from being completely filled with an insulating material or the like in the region shared with the exhaust hole 84 of the second wiring groove 28.

  Then, when the first substrate 12 and the second substrate 50 before etching are bonded by anodic bonding, oxygen released into the internal space 68 is converted into the second groove (second wiring groove 28), the third groove (discharge groove). 82) can be discharged to the outside of the second substrate 50 through the exhaust hole 84 formed by (82). Therefore, it is not necessary to form the exhaust groove 24 of the first embodiment. Since the functional element 80 of the second embodiment is different only in that the exhaust groove is not formed but the exhaust groove is formed, the description of the manufacturing method is omitted.

  FIG. 9 shows a functional element according to the third embodiment. FIG. 9A is a partial plan view, and FIG. 9B is a partial side view. Unlike the first embodiment and the second embodiment, the functional element 90 according to the third embodiment does not form the recess 20 in the first substrate 12, and is on the side facing the first substrate 12 of the second substrate 50. A recess 92 is formed. A movable portion 94 (movable portion 54) is formed at a position facing the concave portion 92 of the second substrate 50. On the other hand, in the first substrate 12, the exhaust groove 25 is formed to extend from the outer peripheral portion 16 of the first substrate 12 to a position facing the recess 92 of the second substrate 50. During the anodic bonding between the first substrate 12 and the second substrate 50 before etching, oxygen is released into the internal space 98 formed by the recess 92 and the first substrate 12. However, since the internal space 98 communicates with the outside through the exhaust hole 100 formed by the exhaust groove 25 and the first substrate 12, oxygen released into the internal space 98 can be exhausted to the outside. The recess 92 is formed by the above-described etching or the like before the second substrate 50 is stacked on the first substrate 12.

  The concave portions (the concave portion 20 of the first embodiment and the concave portion 92 of the second embodiment) are for avoiding joining / interference between the movable portion 54 and the movable portion 94 and the first substrate 12, so that the first It can be formed on the substrate 12 and / or the second substrate 50.

  FIG. 10 shows a functional element according to the fourth embodiment. FIG. 10A is a partial plan view before forming a movable part or the like on the second substrate, FIG. 10B is a cross-sectional view taken along the line AA in FIG. 10A, and FIG. 10C is the second substrate. It is a partial top view after forming a movable part etc. in FIG. The functional element 110 according to the fourth embodiment forms the recess 20 in the first substrate 12 as in the first and second embodiments, but the exhaust groove 112 extends from the end of the second substrate 50 to the first substrate 12. It differs in that it is formed up to the surface facing the recess 20 of the above. As a result, an exhaust hole 114 is formed by the second substrate 50 and the exhaust groove 112, and the internal space 68 formed by the recess 20 and the second substrate 50 before etching communicates with the outside through the exhaust hole 114. . Then, as shown in FIG. 10C, after the formation of the movable portion 54 and the like by etching, the region facing the concave portion 20 (cavity portion 74) of the exhaust hole 114 is cut off.

  FIG. 11 shows a functional element according to the fifth embodiment. In the functional element 170 according to the fifth embodiment, the recess 20 is formed in the first substrate 12 as in the first and second embodiments, but the second substrate 50 is etched in the region (cavity 74). The difference is that the second substrate 50 is stacked on the first substrate 12 after the through hole 172 penetrating the space 68 is formed. That is, the through-hole 172 is formed in the cavity 74 formed by etching and at a position facing the recess 20. Thereby, oxygen released into the internal space 68 during the anodic bonding between the first substrate 12 and the second substrate 50 can be discharged from the through hole 172. In addition, the through-hole 172 disappears after the movable part is formed by etching. For this reason, since it is not necessary to seal the through-hole 172 after forming a movable part etc., manufacturing efficiency improves.

  FIG. 12 shows a functional element according to the sixth embodiment. 12A is a plan view, and FIG. 12B is a schematic view seen from the side. The functional element 120 according to the sixth embodiment has a stacked structure of a first substrate 122 and a second substrate 130. The second substrate 130 includes a movable portion 132, a support portion 142 that supports the movable portion 132, It is formed by. The movable portion 132 connects the flap plate 134, the position away from the balance position of the flap plate 134, and the support portion 142, the connecting portion 136 serving as the rotation axis of the flap plate 134, and the flap plate 134. The movable electrode 138 and the movable electrode 140 are formed on a surface facing the first substrate 122. Further, the movable electrode 138 and the movable electrode 140 are connected to one side of the flap plate 134 so as to sandwich the connecting portion 136, respectively. In addition, the movable electrode 138 and the movable electrode 140 can be electrically connected to the outside of the second substrate 130 via the connecting portion 136.

  On the other hand, in order to avoid interference with the flap plate 134, the first substrate 122 has a recess 124 formed at a position facing the flap plate 134, and a fixed electrode 126 and a fixed electrode 128 are formed at the bottom of the recess 124. The fixed electrode 126 is formed at a position facing the movable electrode 138 of the first substrate 122, and the fixed electrode 128 is formed at a position facing the movable electrode 140 of the second substrate.

  In the present embodiment as well, the first substrate 122 and the second substrate 130 can be joined by anodic bonding, but the exhaust groove 144 may be formed in the first substrate 122 as in the first embodiment. Also in this embodiment, the flap plate 134 and the connecting portion 136 are formed by etching, but anodic bonding may be performed after the through hole 146 is formed in the etched region, as in the fifth embodiment. The movable electrode 138, the movable electrode 140, the fixed electrode 126, and the fixed electrode 128 need to be formed before the anodic bonding between the first substrate 122 and the second substrate 130 is performed.

  In the present embodiment, when a voltage is applied between the movable electrode and the fixed electrode, an electrostatic capacity is generated between the movable electrode 138 and the fixed electrode 126, and static electricity is generated between the movable electrode 140 and the fixed electrode 128. Electric capacity is generated. For example, when the acceleration is received from the normal direction of the second substrate 130, the flap plate 134 rotates around the connecting portion. In this case, since the flap plate 134 is heavier when the movable electrode 138 is provided, the side on which the movable electrode 138 is provided is displaced in a direction opposite to the direction of acceleration according to the law of inertia. Therefore, the electrostatic capacity between the movable electrode 138 and the fixed electrode 126 and the electrostatic capacity between the movable electrode 140 and the fixed electrode 128 are in a relationship in which one increases and the other decreases. Therefore, by taking the difference between the two, the magnitude of the physical quantity such as acceleration and its direction (the normal direction of the second substrate 130) can be detected.

  FIG. 13 shows a functional element according to the seventh embodiment. The functional element 150 according to the seventh embodiment has a stacked structure of the first substrate 152 and the second substrate, but the movable portion is formed such that a part of the second substrate 158 is thin and the main surface of the second substrate 158 is formed. It is formed as a diaphragm 160 that can be bent and deformed by an external force from the normal direction. A movable electrode 162 is formed on the first substrate 152 side of the diaphragm 160.

  The first substrate 152 has a recess 154 formed at a position facing the second substrate 158, and has a fixed electrode 156 at a position facing the movable electrode 162 on the bottom surface of the recess 154. In the present embodiment as well, the first substrate 152 and the second substrate 158 can be joined by anodic bonding, but the exhaust groove 164 may be formed in the first substrate 152 as in the first embodiment. Further, as described above, for convenience of handling, the second substrate 158 is anodic bonded to the first substrate 152 with a thickness larger than necessary, and the diaphragm 160 is formed by thinning the second substrate 158 after bonding. May be. As described above, the movable electrode 162 and the fixed electrode 156 need to be formed before anodic bonding of the first substrate 152 and the second substrate 158 is performed.

  In this embodiment, for example, when an acceleration is applied in a direction perpendicular to the normal direction of the second substrate 158, the diaphragm 160 bends and deforms toward the opposite side of the acceleration according to the law of inertia. When the internal space 166 is hermetically sealed, the diaphragm 160 is bent and deformed due to a pressure difference between the pressure in the internal space 166 and the outside. As a result, a change in electrostatic capacitance between the movable electrode 162 and the fixed electrode 156 can be measured to detect the magnitude and direction of the physical quantity.

  In any functional element according to any of the embodiments, a physical quantity sensor can be constructed by connecting to an integrated circuit (IC) or the like that drives the functional element. For example, by forming the IC as an angular velocity detection circuit, an acceleration detection circuit, or a pressure detection circuit, it can be configured as a gyro sensor, an acceleration sensor, or a pressure sensor.

  In addition, an electronic device in which the functional element according to any of the embodiments is mounted on a digital camera, a personal computer, a mobile phone, a medical device, various measuring devices, or the like can be constructed.

  As described above, the functional element, the method for manufacturing the functional element, the physical quantity sensor, and the electronic device of the present invention have been described based on the illustrated embodiments, but the present invention is not limited to these. For example, in the above description, the concave portion is formed in at least one of the first substrate and the second substrate to form the internal space. However, the first substrate and the second substrate are used using the flat first substrate and the second substrate. The internal space may be formed by bonding both substrates via a spacer. Further, the embodiment is not limited to the above-described embodiment as long as the plurality of first fixed electrode fingers 62 and second fixed electrode fingers 64 arranged in a comb-like shape are spatially separated from each other.

  Further, the number, arrangement, size, and the like of the first fixed electrode fingers 62 and the second fixed electrode fingers 64 and the movable electrode fingers 58 provided so as to mesh with the first fixed electrode fingers 62 and the second fixed electrode fingers 64 are not limited to the above-described embodiments.

  Further, the movable portion 54 may be configured to be displaced in a direction perpendicular to the direction of the arrow in FIG. 1, or may be configured to rotate with the direction of the arrow in FIG. In this case, the physical quantity may be detected based on a change in capacitance due to a change in the facing area of the first fixed electrode finger 62 and the second fixed electrode finger 64 and the movable electrode finger 58.

  In the first to fifth embodiments described above, the case where the functional element is used as the physical quantity sensor element has been described. However, the present invention is not limited to the physical quantity sensor element. For example, different voltages are applied to each fixed electrode finger and movable electrode finger. The functional element of the present invention may be used as a resonator that oscillates at a natural frequency by applying and driving the movable electrode finger with Coulomb force.

DESCRIPTION OF SYMBOLS 10 ......... Function element, 12 ......... 1st board | substrate, 14 ......... Joint part, 16 ......... Outer peripheral part, 18 ......... Terminal part, 20 ......... Recessed part, 24 ......... Exhaust groove, 25 ......... Exhaust groove, 26 ......... First wiring groove, 28 ......... Second wiring groove, 30 ......... Third wiring groove, 32 ......... First wiring, 34 ......... First bump, 36 ......... First terminal electrode, 38 ......... Second wiring, 40 ......... Second bump, 42 ......... Second terminal electrode, 44 ......... Third wiring, 46 ......... Third bump, 48 ......... Third terminal electrode, 50 ......... Second substrate, 52 ......... Supporting part, 54 ......... Moving part, 56 ......... Beam, 58 ......... Moving electrode finger, 60 ...... Flexible 62,... First fixed electrode finger, 64... Second fixed electrode finger, 66... Lid, 68 ... Internal space, 70 ... Exhaust hole, 72 Exhaust hole, 74 ……… Cavity 76 ......... Cavity part, 78 ......... Adhesive layer, 80 ......... Function element, 82 ......... Discharge groove, 84 ......... Exhaust hole, 90 ......... Function element, 92 ......... Recess, 94 ... …… Moving part, 96 …… Exhaust groove, 98 ……… Internal space, 100 ……… Exhaust hole, 110 ……… Function element, 112 ……… Exhaust groove, 114 ……… Exhaust hole, 120 …… ... functional element 122 ... ... first substrate 124 ... ... recess, 126 ... ... fixed electrode 128 ... ... fixed electrode 130 ... ... second substrate 132 ... ... movable part 134 ... ... Flap plate, 136 ......... Connecting part, 138 ......... Moving electrode, 140 ...... Moving electrode, 142 ...... Supporting part, 144 ...... Exhaust groove, 146 ...... Through hole, 150 ...... Functional element 152... First substrate 154... Recessed portion 156... Fixed electrode 158. 2 substrate, 160 ......... diaphragm, 162 ......... movable electrode, 164 ......... exhaust groove, 166 ......... internal space, 170 ......... functional element, 172 ......... through hole.

Claims (5)

A first substrate;
A first fixed electrode provided on one side of the first substrate;
With
An internal space is provided between the first substrate and the first fixed electrode,
The first substrate is provided with a first wiring groove in which the first wiring is disposed and the internal space communicates with the outside.
The first fixed electrode is disposed so as to overlap at least a part of the first wiring groove in a plan view of the first substrate ,
The functional element, wherein the first fixed electrode is electrically connected to the first wiring provided in the first wiring groove.   The conductive layer is provided between the first fixed electrode and the first wiring, and the first fixed electrode and the first wiring are electrically connected to each other. Functional element. A second fixed electrode spaced from the first fixed electrode;
A movable electrode provided between the first fixed electrode and the second fixed electrode;
Have
The first substrate is provided with a second wiring groove on which the second wiring is arranged and communicates with the outside.
The second fixed electrode is disposed so as to overlap at least a part of the second wiring groove in a plan view of the first substrate ;
The functional element according to claim 1, wherein the second fixed electrode is electrically connected to the second wiring provided in the second wiring groove. The second fixed electrode is
Arranged to straddle the first wiring groove,
The first fixed electrode is
Electrically connected to the first wiring and insulated from the second wiring;
The second fixed electrode is
The functional device according to claim 2, wherein the functional element is electrically connected to the second wiring and insulated from the first wiring. A lid provided to cover the first fixed electrode and the second fixed electrode;
5. The functional device according to claim 1, wherein the outside is outside a portion covered with the lid. 6.

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