JP2019158716A - Capacitive pressure sensor - Google Patents

Abstract

To provide a capacitive pressure sensor which provides high measurement accuracy even when a flexible substrate is bent.SOLUTION: A capacitive pressure sensor comprises: a flexible substrate having a first electrode; a rigid substrate arranged to face the flexible substrate and provided with a second electrode disposed to face the first electrode with a hollow section therebetween; and a joining section provided between the flexible substrate and the rigid substrate to surround the hollow section and configured to join the flexible substrate and the rigid substrate. In a planar view from a direction normal to a surface of the rigid substrate facing the flexible substrate, the first and second electrodes do not lie beyond an outer circumference of the joining section.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a capacitive pressure sensor.

  The pressure sensor mainly detects the pressure of gas or liquid, and is applied to various devices as an atmospheric pressure sensor, an altitude sensor, or a water pressure sensor. In recent years, as an aspect of using this as an altitude sensor, its application range includes application to a navigation device for obtaining position information and application to a measuring instrument for precisely measuring the amount of movement of a user. It is spreading.

A capacitance type pressure sensor is known as a MEMS (Micro Electro Mechanical System) sensor chip. The capacitive pressure sensor includes a substrate having a movable electrode and a hard substrate having a fixed electrode. A capacitance corresponding to the gap is generated between the movable electrode and the fixed electrode. When a pressure is applied to the capacitance type pressure sensor, the substrate having the movable electrode bends, and the gap between the movable electrode and the fixed electrode changes to detect a change in capacitance. A pressure corresponding to the change in capacitance is detected. A flexible pressure sensor device has been proposed (see Patent Document 1).

JP 2007-178256 A

  An object of the present invention is to provide a capacitive pressure sensor with high measurement accuracy even when a flexible substrate is bent.

  The present invention employs the following means in order to solve the above-described problems. That is, the present invention provides a flexible substrate including a first electrode and a second electrode that is disposed to face the flexible substrate and that is disposed to face the first electrode through a hollow portion between the first electrode and the flexible substrate. A hard board including: a hard board, and a joint between the flexible board and the hard board that surrounds the hollow part and joins the flexible board and the hard board. The capacitance-type pressure sensor in which the first electrode and the second electrode do not protrude outward from the outer periphery of the joint portion in a plan view from the normal direction of the surface of the substrate facing the flexible substrate.

  The first electrode of the flexible substrate and the second electrode of the hard substrate do not protrude outward from the outer periphery of the joint in a plan view from the normal direction of the surface facing the flexible substrate of the hard substrate of the capacitive pressure sensor. Thereby, a pressure is applied to the capacitance type pressure sensor, and a change in parasitic capacitance after the first electrode is bent is suppressed. That is, the difference between the parasitic capacitance before the pressure is applied to the pressure sensor and the parasitic capacitance after the pressure is applied to the pressure sensor is reduced. Therefore, according to the capacitance type pressure sensor, since the change of the parasitic capacitance is suppressed, the measurement accuracy of the capacitance type pressure sensor is improved. Thereby, it is possible to provide a capacitive pressure sensor with high measurement accuracy even when the flexible substrate is bent.

In the capacitance type pressure sensor, a metal film provided in the hollow portion and electrically connected to the second electrode is provided, and an outer peripheral portion of the first electrode is supported by the joint portion, The distance between the first electrode and the metal film is shorter from the center side of the hollow part toward the outer peripheral side of the hollow part. Since the outer peripheral portion of the first electrode is supported by the joint portion, when the pressure is applied to the pressure sensor and the flexible substrate is bent, the amount of bending of the central portion of the first electrode is large, and the first electrode The amount of bending of the outer peripheral portion of is small. When the flexible substrate is bent, the distance between the first electrode and the metal film on the center side of the hollow portion is small, and the distance between the first electrode and the metal film on the outer peripheral side of the hollow portion is small. . As a result, the measurement sensitivity of the capacitive pressure sensor is improved, and the measurement accuracy of the capacitive pressure sensor is improved.

  In the capacitive pressure sensor, the joint includes a metal member disposed on the flexible substrate side and a highly moisture-proof insulating film disposed on the hard substrate side. Thereby, the moisture absorption of the insulating film in a junction part is suppressed, and the measurement precision of a capacitance-type pressure sensor improves. The capacitance type pressure sensor includes a signal line electrically connected to the second electrode and provided on the flexible board and a shield line provided on the flexible board, with the signal line sandwiched therebetween. A shield wire is arranged. Thereby, the noise mixed in the signal propagated by the signal line is suppressed, and the measurement accuracy of the capacitive pressure sensor is improved. A capacitance type pressure sensor is provided on the flexible substrate and connected to the first electrode, and a temperature sensor provided on the flexible substrate and disposed in the vicinity of the heat conductive member. . Thereby, the temperature sensor can measure the temperature of the heat conductive member as the temperature of the first electrode.

  The capacitive pressure sensor includes a shield film provided on a surface of the flexible substrate opposite to the surface facing the hard substrate. When the shield film covers the flexible substrate, moisture absorption of the flexible substrate is suppressed, and the measurement accuracy of the capacitive pressure sensor is improved. In the capacitive pressure sensor, the first electrode and the shield film are at the same potential. This suppresses the generation of parasitic capacitance when the human body touches the shield film, thereby improving the measurement accuracy of the capacitance pressure sensor. The capacitive pressure sensor includes an insulative protruding member provided in the hollow portion and disposed on the second electrode. As a result, when pressure is applied to the capacitive pressure sensor and the flexible substrate is bent, the protruding member prevents contact between the first electrode and the second electrode. Short circuit is avoided.

  In the capacitive pressure sensor, the flexible substrate includes a plurality of the first electrodes, and the plurality of second electrodes, the plurality of hard substrates, and the plurality of joints corresponding to the plurality of first electrodes. Prepare. Accordingly, it is possible to perform pressure surface measurement using a capacitance type pressure sensor in which a flexible substrate and a plurality of hard substrates are joined.

  According to the present invention, it is possible to provide a capacitive pressure sensor with high measurement accuracy even when a flexible substrate is bent.

Drawing 1 is a sectional view showing an example of a pressure sensor concerning an embodiment. FIG. 2 is a plan view of the movable electrode. FIG. 3 is a plan view of the fixed electrode. FIG. 4 is a cross-sectional view illustrating an example of a pressure sensor according to the embodiment. FIG. 5 is an example of a plan view of the pressure sensor. FIG. 6A is a cross-sectional view illustrating an example of a pressure sensor according to the embodiment. FIG. 6B is a cross-sectional view illustrating an example of a pressure sensor according to the embodiment. Drawing 7 is a figure showing an example of a manufacturing process of a pressure sensor concerning an embodiment. Drawing 8 is a figure showing an example of a manufacturing process of a pressure sensor concerning an embodiment. Drawing 9 is a figure showing an example of a manufacturing process of a pressure sensor concerning an embodiment. Drawing 10 is a figure showing an example of a manufacturing process of a pressure sensor concerning an embodiment. FIG. 11 is a diagram illustrating an example of the manufacturing process of the pressure sensor according to the embodiment. Drawing 12 is a figure showing an example of a manufacturing process of a pressure sensor concerning an embodiment. Drawing 13 is a figure showing an example of a manufacturing process of a pressure sensor concerning an embodiment. Drawing 14 is a figure showing an example of a manufacturing process of a pressure sensor concerning an embodiment. FIG. 15 is a diagram illustrating an example of a manufacturing process of the pressure sensor according to the embodiment. FIG. 16 is a diagram illustrating an example of a manufacturing process of the pressure sensor according to the embodiment. FIG. 17 is a diagram illustrating an example of a manufacturing process of the pressure sensor according to the embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. The embodiment described below is one aspect of the present application and does not limit the technical scope of the present application.

<Application example>
First, an example of a scene to which the present invention is applied will be described. FIG. 1 is a cross-sectional view illustrating an example of a pressure sensor 100 according to the embodiment. The pressure sensor 100 is an example of a capacitive pressure sensor. The pressure sensor 100 includes a movable part 10 and a fixed substrate part 20. The movable part 10 has flexibility. The movable part 10 includes a sheet substrate 11 and a movable electrode 12. The movable electrode 12 has a conductor part 13 and a plating part 14. The movable part 10 is an example of a flexible substrate. The sheet substrate 11 may be an example of a flexible substrate. The movable electrode 12 is an example of a first electrode.

  The fixed substrate unit 20 includes a substrate unit 21, a fixed electrode 22, and a metal film 25. The fixed substrate portion 20 is disposed so as to face the movable portion 10 with a hollow portion (gap) 30 between the fixed substrate portion 20 and the movable portion 10. The fixed electrode 22 is disposed opposite to the movable electrode 12 through the hollow portion 30 between the fixed electrode 22 and the movable electrode 12. The insulating unit 23 includes a first insulating film 26 and a second insulating film 27. The insulating part 23 is provided on the fixed substrate part 20 so as to surround the fixed electrode 22. The insulating part 23 and the wall part 24 are provided so as to surround the hollow part 30, and join the movable part 10 and the fixed substrate part 20. The fixed substrate unit 20 is an example of a hard substrate. The fixed electrode 22 is an example of a second electrode. The insulating part 23 is arranged on the fixed substrate part 20 side, and the wall part 24 is arranged on the movable part 10 side. The insulating part 23 and the wall part 24 are an example of a joint part. Further, the pressure sensor 100 includes a shield film 31 provided on the movable part 10. In the embodiment, the formation of the metal film 25 and the shield film 31 may be omitted. The pressure sensor 100 measures the pressure applied to the movable electrode 12 by detecting a change in capacitance caused by the bending of the movable electrode 12.

FIG. 2 is a plan view of the movable electrode 12. FIG. 3 is a plan view of the fixed electrode 22. 1 corresponds to the cross section taken along line BB in FIG. 2 and the cross section taken along line DD in FIG. In the example of FIG. 2, the shape of the movable electrode 12 in a plan view is a circle, and in the example of FIG. 3, the shape of the fixed electrode 22 in a plan view is a circle. The shape of the movable electrode 12 in the plan view and the shape of the fixed electrode 22 in the plan view may be other shapes such as an ellipse and a rectangle. As shown in FIG. 2, the movable electrode 12 is connected to a ground (GND) line 16. Further, the signal line 15 is disposed to face the ground line 16 with the movable electrode 12 interposed therebetween. The signal line 15 is separated from the movable electrode 12. The movable electrode 12, the signal line 15, and the ground line 16 are provided on the surface of the movable unit 10 that faces the fixed substrate unit 20. Specifically, the movable electrode 12, the signal line 15, and the ground line 16 are provided on the lower surface of the sheet substrate 11. The lower surface of the sheet substrate 11 faces the upper surface of the substrate unit 21. In FIG. 2, the outline of the sheet substrate 11 is indicated by a dotted line. As shown in FIG. 3, the fixed electrode 22 is connected to the signal pad 28. A ground pad 29 is disposed opposite to the signal pad 28 with the fixed electrode 22 interposed therebetween.

  The movable electrode 12 and the fixed electrode 22 protrude outward from the outer periphery of the wall portion 24 in a plan view from the normal direction (direction indicated by arrow A in FIG. 1) of the surface of the fixed substrate portion 20 facing the movable portion 10. Absent. Thereby, pressure is applied to the pressure sensor 100, and the change in the parasitic capacitance after the movable electrode 12 is bent is suppressed. That is, the difference between the parasitic capacitance before the pressure is applied to the pressure sensor 100 and the parasitic capacitance after the pressure is applied to the pressure sensor 100 is reduced. Thereby, since the change of parasitic capacitance is suppressed, the measurement accuracy of the pressure sensor 100 is improved. According to the embodiment, it is possible to provide the pressure sensor 100 with high measurement accuracy even when the movable part 10 is bent.

<Embodiment>
FIG. 4 is a cross-sectional view illustrating an example of the pressure sensor 100 according to the embodiment. FIG. 5 is an example of a plan view of the pressure sensor 100. FIG. 4 shows a cross section taken along line FF in FIG. 4 corresponds to the cross section taken along the line CC in FIG. 2 and the cross section taken along the line EE in FIG. In FIG. 5, four pressure sensors 100 (100A, 100B, 100C, and 100D) are illustrated, and a connector 200 and a capacitance measurement circuit 300 are illustrated. In the example of FIG. 5, four pressure sensors 100 are illustrated, but the number of pressure sensors 100 can be increased or decreased. The four pressure sensors 100 share the sheet substrate 11.

  The movable part 10 includes a sheet substrate 11, a movable electrode 12, a signal line 15, and a ground line 16. The sheet substrate 11 is formed of a flexible member (for example, polyimide). A movable electrode 12, a signal line 15, and a ground line 16 are provided on the lower surface of the sheet substrate 11. The movable electrode 12, the signal line 15, and the ground line 16 have conductivity. The movable electrode 12 has a conductor portion 13A and a plating portion 14B. The signal line 15 has a conductor portion 13B and a plated portion 14B. The ground line 16 has a conductor portion 13C and a plated portion 14C. The conductor portions 13A, 13B, and 13C are made of a metal such as Cu (copper), for example. The plated portions 14A, 14B, and 14C are made of, for example, Ti (titanium), Au (gold), or the like. The conductor portions 13A, 13B, and 13C are collectively referred to as the conductor portion 13, and the plating portions 14A, 14B, and 14C are collectively referred to as the plating portion 14.

  The fixed substrate unit 20 includes a substrate unit 21, a fixed electrode 22, a metal film 25, a signal pad 28, and a ground pad 29. The substrate unit 21 is formed of a member (for example, glass) that does not easily deform. The thickness of the substrate unit 21 is, for example, 300 μm or more and 600 μm or less, but is not limited to this range. Since the substrate portion 21 is formed of a member that does not easily deform, even if the movable portion 10 is bent by applying pressure to the sheet substrate 11, the deformation of the fixed substrate portion 20 is suppressed. A fixed electrode 22, a signal pad 28, and a ground pad 29 are disposed on the upper surface of the substrate portion 21. The upper surface of the substrate unit 21 faces the lower surface of the sheet substrate 11. The fixed electrode 22, the metal film 25, the signal pad 28, and the ground pad 29 have conductivity. The fixed electrode 22, the signal pad 28, and the ground pad 29 are made of, for example, Cr (chrome). The metal film 25 is made of, for example, Ti, Au or the like.

The fixed substrate portion 20 is provided with an insulating portion 23 that surrounds the periphery of the fixed electrode 22, the signal pad 28, and the ground pad 29 and covers a part of the fixed electrode 22, the signal pad 28, and the ground pad 29. The insulating unit 23 includes a first insulating film 26 and a second insulating film 27. The first insulating film 26 is made of, for example, TEOS (tetraethoxysilane), SiO ₂ (silicon dioxide), or the like. The second insulating film 27 is made of SiN (silicon nitride). A wall portion 24 </ b> A is provided on the insulating portion 23 </ b> A that covers a part of the fixed electrode 22. The insulating part 23 </ b> A and the wall part 24 </ b> A are provided on the substrate part 21 so as to surround the hollow part 30. A wall portion 24B is provided on the insulating portion 23B covering a part of the signal pad 28. A wall portion 24 </ b> C is provided on the insulating portion 23 </ b> C that covers a part of the ground pad 29. The wall portions 24A, 24B, and 24C are made of a metal such as Cu, for example. In addition, the insulating parts 23A, 23B, and 23C are collectively referred to as the insulating part 23.

  The insulating portion 23 (23A, 23B, 23C) and the wall portion 24 (24A, 24B, 24C) join the movable portion 10 and the fixed substrate portion 20 so that the movable portion 10 and the fixed substrate portion 20 are integrated. A pressure sensor 100 is formed. The wall portion 24B is in contact with the signal line 15 and the signal pad 28. The signal line 15 is electrically connected to the signal pad 28 through the wall 24B. Since the fixed electrode 22 is connected to the signal pad 28, the signal line 15 is electrically connected to the fixed electrode 22. The ground line 16 is electrically connected to the ground pad 29 through the wall 24C. The pressure sensor 100 operates as a capacitor using the movable electrode 12 and the fixed electrode 22 as electrode plates.

  As shown in FIG. 5, a plurality of signal lines 15 are connected to the connector 200. The connector 200 is connected to the capacitance measurement circuit 300. As illustrated in FIG. 5, a plurality of pressure sensors 100 can be arranged while sharing the sheet substrate 11. That is, by providing a plurality of movable electrodes 12 on a single sheet substrate 11, the plurality of movable electrodes 12 and the plurality of fixed substrate portions 20 are arranged on the single sheet substrate 11 in rows, lattices, or arrays. It is possible. Therefore, the pressure sensor 100 has a plurality of sensor elements sharing a single sheet substrate 11. In this case, the plurality of movable electrodes 12 are separated from each other, and the plurality of fixed substrate portions 20 are separated from each other. Therefore, when a pressure is applied to the pressure sensor 100, one of the adjacent movable parts 10 does not hinder the other substrate of the adjacent movable parts 10 from being bent. Therefore, the bending of the movable part 10 when a pressure is applied to the pressure sensor 100 is not hindered, and the pressure applied to the pressure sensor 100 can be measured with high accuracy.

  In the pressure sensor 100, when a pressure is applied to the pressure sensor 100 from above the hollow portion 30, the movable portion 10 bends toward the fixed substrate portion 20 according to the applied pressure. Further, when no pressure is applied to the pressure sensor 100, the pressure sensor 100 returns to the state before the pressure is applied. That is, in the pressure sensor 100, the distance between the movable electrode 12 and the fixed electrode 22 varies according to the applied pressure. When the distance between the movable electrode 12 and the fixed electrode 22 varies, the capacitance of the pressure sensor 100 varies. For example, the pressure applied to the pressure sensor 100 is detected by measuring the variation in the capacitance of the pressure sensor 100 by the capacitance measuring circuit 300 illustrated in FIG.

  In plan view, when the movable electrode 12 and the fixed electrode 22 protrude outward from the outer periphery of the wall portion 24, the parasitic capacitance changes greatly after the movable electrode 12 is bent. According to the embodiment, the movable electrode 12 and the fixed electrode 22 do not protrude outward from the outer periphery of the wall portion 24 in plan view. Since the change in the parasitic capacitance after the movable electrode 12 is bent is suppressed, the measurement accuracy of the pressure sensor 100 is improved.

The first insulating film 26 is a silicon oxide film formed of TEOS, SiO ₂ or the like. The silicon oxide film has a hygroscopic property. If the silicon oxide film absorbs moisture, measurement of the pressure sensor 100 may be adversely affected. The second insulating film 27 is a silicon nitride film formed of SiN. The silicon nitride film is a highly moisture-proof member. The second insulating film 27 is an example of a highly moisture-proof insulating film. Since the insulating part 23 includes the second insulating film 27, moisture absorption of the insulating part 23 is suppressed, and the measurement accuracy of the pressure sensor 100 is improved. For example, as shown in FIG. 4, the second insulating film 27 covers the first insulating film 26, so that the moisture absorption of the first insulating film 26 is suppressed and the measurement accuracy of the pressure sensor 100 is improved.

As shown in FIG. 4, a metal film 25 is provided on the fixed electrode 22 in the hollow portion 30. The metal film 25 is electrically connected to the fixed electrode 22. The outer peripheral part of the movable electrode 12 is supported by the insulating part 23A and the wall part 24A. The wall portion 24A is an example of a metal member. In the example of FIG. 4, the metal film 25 has a step that increases from the center side of the hollow portion 30 toward the outer peripheral side of the hollow portion 30. Therefore, the distance between the movable electrode 12 and the metal film 25 is shorter from the center side of the hollow portion 30 toward the outer peripheral side of the hollow portion 30. Further, the metal film 25 may have an inclined surface that increases from the center side of the hollow portion 30 toward the outer peripheral side of the hollow portion 30. When pressure is applied to the pressure sensor 100 from above the hollow portion 30, the movable portion 10 bends toward the fixed substrate portion 20. When the movable part 10 bends, the pressure applied to the pressure sensor 100 is detected based on the distance between the movable electrode 12 and the fixed electrode 22. Since the outer peripheral portion of the movable electrode 12 is supported by the insulating portion 23A and the wall portion 24A, the deflection amount of the central portion of the movable electrode 12 is large, and the deflection amount of the outer peripheral portion of the movable electrode 12 is small. For this reason, when the movable part 10 bends, the distance between the movable electrode 12 and the metal film 25 on the center side of the hollow part 30 and the distance between the movable electrode 12 and the metal film 25 on the outer peripheral side of the hollow part 30. The difference from the distance becomes smaller. Thereby, the measurement sensitivity of the pressure sensor 100 is improved, and the measurement accuracy of the pressure sensor 100 is improved.

  As shown in FIG. 4, a shield film 31 is provided on the opposite surface of the movable portion 10 to the surface facing the fixed substrate portion 20. The shield film 31 is made of a metal such as Ti or Al (aluminum), for example. By covering the sheet substrate 11 with the shield film 31, moisture absorption of the sheet substrate 11 is suppressed, and the measurement accuracy of the pressure sensor 100 is improved. The movable electrode 12 and the shield film 31 may be at the same potential. For example, as shown in FIG. 6A, the operational amplifier 33 may be connected to the movable electrode 12 and the shield film 31 so that the movable electrode 12 and the shield film 31 have the same potential. FIG. 6A is a cross-sectional view illustrating an example of the pressure sensor 100 according to the embodiment. When the human body comes into contact with the sheet substrate 11, parasitic capacitance is generated between the human body and the movable electrode 12. Since the movable electrode 12 and the shield film 31 have the same potential, generation of parasitic capacitance when the human body touches the shield film 31 is suppressed. The generation of the parasitic capacitance is suppressed, and the change in the parasitic capacitance after the pressure is applied to the pressure sensor 100 and the movable electrode 12 is bent is suppressed, so that the measurement accuracy of the pressure sensor 100 is improved.

  As shown in FIG. 5, a plurality of shield lines 32 are arranged with each signal line 15 interposed therebetween. A plurality of shield wires 32 are connected to the connector 200. The shield wire 32 is made of a metal such as Cu or Al, for example. The shield wire 32 may be a conductive resin. By arranging the shield line 32 with the signal line 15 in between, noise mixed in the signal propagated by the signal line 15 can be suppressed. Thereby, the measurement accuracy of the pressure sensor 100 is improved. In the embodiment, the formation of the shield wire 32 may be omitted.

  A connecting wire 41, a heat conductive member 42, and a temperature sensor 43 are provided on the movable portion 10. As shown in FIG. 5, the connection line 41 is disposed between the adjacent movable electrodes 12, and the adjacent movable electrodes 12 are connected to each other by the connection line 41. The connection line 41 is formed of the same material as that of the movable electrode 12, but the connection line 41 may be formed of a heat conductive resin. By connecting the movable electrodes 12 to each other, the temperatures of the plurality of movable electrodes 12 are equalized. A thermally conductive member 42 is connected to the movable electrodes 12 at both ends of the plurality of movable electrodes 12. Since the heat of the plurality of movable electrodes 12 is transmitted to the heat conductive member 42, the temperature of the plurality of movable electrodes 12 and the temperature of the heat conductive member 42 coincide. A temperature sensor 43 is disposed in the vicinity of the heat conductive member 42. As illustrated in FIG. 5, the temperature sensor 43 may be disposed adjacent to the heat conductive member 42. The temperature sensor 43 measures the temperature of the heat conductive member 42. Thereby, the temperature sensor 43 can measure the temperature of the heat conductive member 42 as the temperature of the movable electrode 12.

  The temperature sensor 43 is connected to the connector 200. The capacitance measuring circuit 300 acquires temperature data measured by the temperature sensor 43. When the thermal expansion coefficients of the sheet substrate 11, the movable electrode 12, the substrate unit 21, and the fixed electrode 22 are different, the capacitance changes due to a temperature change. The capacitance measuring circuit 300 corrects the capacitance using the temperature data and measures the pressure applied to the movable electrode 12. Thereby, the measurement accuracy of the pressure sensor 100 is improved. In the embodiment, the formation of the connection line 41, the heat conductive member 42, and the temperature sensor 43 may be omitted.

  FIG. 6B is a cross-sectional view illustrating an example of the pressure sensor 100 according to the embodiment. In FIG. 6B, a part of the pressure sensor 100 is shown enlarged. As shown in FIG. 6B, a protruding member 34 is provided on the fixed electrode 22 in the hollow portion 30. The number of the protruding members 34 may be singular or plural. The protruding member 34 is an insulating member. The protruding member 34 may be a silicon nitride film formed of SiN. The second insulating film 27 and the protruding member 34 may be formed of the same material. The second insulating film 27 and the protruding member 34 may be formed by the same process. When pressure is applied to the pressure sensor 100 from above the hollow portion 30, the movable portion 10 bends toward the fixed substrate portion 20. When the movable part 10 bends and the movable electrode 12 comes into contact with the fixed electrode 22 by bending the movable electrode 12, the movable electrode 12 and the fixed electrode 22 are short-circuited. When the movable portion 10 is bent, the protruding member 34 prevents the movable electrode 12 and the fixed electrode 22 from contacting each other, so that a short circuit between the movable electrode 12 and the fixed electrode 22 is avoided. The protruding member 34 may be provided on the metal film 25 in the hollow portion 30. Further, in the hollow portion 30, the protruding member 34 may be provided on the fixed electrode 22, and the protruding member 34 may be provided on the metal film 25. When the movable part 10 bends, the projecting member 34 prevents contact between the movable electrode 12 and the metal film 25, so that a short circuit between the movable electrode 12 and the metal film 25 is avoided.

<Manufacturing process of pressure sensor 100>
FIG. 7A to FIG. 14B are diagrams showing an example of the manufacturing process of the pressure sensor 100. Hereinafter, an example of a manufacturing process of the pressure sensor 100 will be described with reference to FIGS. 7 (A) to 14 (B).

(Manufacturing process of fixed substrate part 20)
FIG. 7A to FIG. 10B show an example of the manufacturing process of the fixed substrate unit 20. FIGS. 7A, 8 </ b> A, 9 </ b> A, and 10 </ b> A are plan views of the fixed substrate portion 20. FIGS. 7B, 8 </ b> B, 9 </ b> B, and 10 </ b> B are cross-sectional views of the fixed substrate portion 20. 7B, FIG. 8B, FIG. 9B, and FIG. 10B are respectively shown in FIG. 7A, FIG. 8A, FIG. 9A, and FIG. The cross section along each GG line is shown. 7A and 7B, the fixed electrode 22, the signal pad 28, and the ground pad 29 are formed on the surface of the substrate unit 21 that faces the movable unit 10. Each thickness of the fixed electrode 22, the signal pad 28, and the ground pad 29 is, for example, 200 nm, but is not limited to this value. Next, in FIGS. 8A and 8B, the first insulating film 26 is formed so as to cover a part of the fixed electrode 22, a part of the signal pad 28, and a part of the ground pad 29. The thickness of the first insulating film 26 is, for example, 550 nm, but is not limited to this value. Subsequently, in FIGS. 9A and 9B, a second insulating film 27 is formed so as to cover the first insulating film 26. Thus, the insulating part 23A covers a part of the fixed electrode 22, the insulating part 23B covers a part of the signal pad 28, and the insulating part 23C covers a part of the ground pad 29. The insulating portions 23A, 23B, and 23C include a first insulating film 26 and a second insulating film 27. The thickness of the second insulating film 27 is, for example, 100 nm, but is not limited to this value. The fixed electrode 22, the insulating portions 23A, 23B, and 23C, the signal pad 28, and the ground pad 29 are formed in a predetermined pattern, for example, by performing photolithography and etching.

Next, in FIGS. 10A and 10B, the wall portion 24 and the metal film 25 are formed on the fixed substrate portion 20 by performing a plating process. Specifically, the wall 24A is formed on the insulating portion 23A, the wall 24B is formed on the insulating portion 23B, the wall 24C is formed on the insulating portion 23C, and the metal film 25 is formed on the fixed electrode 22. Is done. The wall 24B is in contact with the signal pad 28, and the wall 24B and the signal pad 28 are electrically connected. The wall portion 24C is in contact with the ground pad 29, and the wall portion 24B and the ground pad 29 are electrically connected. The wall portions 24A, 24B, and 24C are collectively referred to as the wall portion 24. The metal film 25 is in contact with the fixed electrode 22, and the metal film 25 is electrically connected to the fixed electrode 22. Further, the metal film 25 covers a part of the second insulating film 27 on the fixed electrode 22, thereby forming a step in the metal film 25. Note that the wall 24 and the metal film 25 may be formed by sputtering. That is, the pattern of the wall 24 and the metal film 25 may be formed by applying a resist and etching after forming a plating layer on the fixed substrate portion 20 by a sputtering apparatus.

(Manufacturing process of movable part 10)
FIG. 11A to FIG. 14B show an example of the manufacturing process of the movable part 10.
FIGS. 11A, 12 </ b> A, 13 </ b> A, and 14 </ b> A are plan views of the movable portion 10. FIGS. 11B, 12 </ b> B, 13 </ b> B, and 14 </ b> B are cross-sectional views of the movable portion 10. 11B, FIG. 12B, FIG. 13B, and FIG. 14B are respectively shown in FIG. 11A, FIG. 12A, FIG. 13A, and FIG. The cross section along each JJ line | wire is shown. In FIGS. 11A and 11B, the conductor portion 13 is formed on the surface of the sheet substrate 11 fixed to the support substrate 50 that faces the fixed substrate portion 20. The conductor portion 13 is planarized by CMP (Chemical Mechanical Polishing). 12A and 12B
Then, the plating part 14 is formed on the conductor part 13. For example, the plated portion 14 may be formed on the conductor portion 13 by forming Ti having a thickness of 50 nm and Au having a thickness of 100 nm on the conductor portion 13. In FIGS. 13A and 13B, the pattern of the conductor portion 13 and the plating portion 14 is formed by performing photolithography and etching. As a result, the movable electrode 12, the signal line 15, the ground line 16, and the connection line 41 are formed on the surface of the sheet substrate 11 that faces the fixed substrate unit 20. In FIG. 14A and FIG. 14B, the support substrate 50 is peeled from the movable portion 10.

(Jointing process of movable part 10 and fixed substrate part 20)
FIG. 15 shows an example of a process of joining the fixed substrate part 20 and the movable part 10. In FIG. 15, the movable portion 10 and the fixed substrate portion 20 are joined. The joining method is not particularly limited. The movable unit 10 and the fixed substrate unit 20 may be bonded by, for example, room temperature bonding. In the room temperature bonding, for example, the surface of the plated portion 14 facing the wall portion 24 and the surface of the wall portion 24 facing the plated portion 14 are smoothed and impurities are removed from the surface. A cleaning process is performed. When the plated part 14 and the wall part 24 subjected to these treatments come into contact with each other, the movable part 10 and the fixed substrate part 20 are joined by an intermolecular force acting between the plated part 14 and the wall part 24. As shown in FIG. 16, a shield film 31 may be formed on the movable portion 10. FIG. 16 shows an example of a process for forming the shield film 31. In FIG. 16, the shield film 31 is formed on the surface opposite to the surface facing the fixed substrate portion 20 of the sheet substrate 11.

  FIG. 17 illustrates a state in which two pressure sensors 100 sharing the sheet substrate 11 are arranged in the pressure sensor 100 manufactured by the processes from FIG. 7A to FIG. 16. In FIG. 17, the fixed substrate part 20 is separated into pieces by dicing. As illustrated in FIG. 17, by sharing the sheet substrate 11 and arranging the plurality of pressure sensors 100, it is possible to expand the area to be subjected to pressure detection. In the example of FIG. 17, two pressure sensors 100 (100A, 100B) are illustrated, but the number of pressure sensors 100 can be increased or decreased.

Further, in the joining process of the movable part 10 and the fixed substrate part 20, the surface of the plating part 14 and the wall part 24 is not flattened in the manufacturing process of the movable part 10 and the fixed substrate part 20 without performing the process of flattening the surface. You may make it secure sex. For example, in the manufacturing process of the movable part 10, the metal (for example, Cu) that becomes the movable electrode 12 may be flattened by CMP with respect to the sheet substrate 11, and the plating part 14 may be formed thereon by a sputtering apparatus. .

<Appendix>
A flexible substrate (10) including a first electrode (12);
A second electrode (22) disposed opposite the flexible substrate (10) and disposed between the first electrode (12) and the first electrode via a hollow portion (30) (12). A hard substrate (20) comprising:
A joint portion (between the flexible substrate (10) and the hard substrate (20)) that is provided so as to surround the hollow portion and joins the flexible substrate (10) and the hard substrate (20). 24)
With
The first electrode (12) and the second electrode (22) are connected to the joint (24) in a plan view from the normal direction of the surface of the hard substrate (20) facing the flexible substrate (10). Does not protrude outward from the outer circumference,
A capacitive pressure sensor (100) characterized by the above.

DESCRIPTION OF SYMBOLS 100, 100A, 100B, 100C, 100D ... Pressure sensor 10 ... Movable part 11 ... Sheet substrate 12 ... Movable electrode 15 ... Signal wire 16 ... Ground wire 20 ... Fixed substrate Part 21: Substrate part 22: Fixed electrode 23, 23A, 23B, 23C ... Insulating part 24, 24A, 24B, 24C ... Wall part 25 ... Metal film 26 ... First insulation Membrane 27 ... Second insulating membrane 30 ... Hollow part

Claims (9)

A flexible substrate including a first electrode;
A hard substrate including a second electrode disposed opposite to the flexible substrate and disposed opposite to the first electrode via a hollow portion between the first electrode;
Between the flexible substrate and the hard substrate, provided so as to surround the hollow portion, a joint portion for joining the flexible substrate and the hard substrate,
With
In the plan view from the normal direction of the surface of the hard substrate facing the flexible substrate, the first electrode and the second electrode do not protrude outward from the outer periphery of the joint portion,
A capacitance type pressure sensor characterized by the above. A metal film provided in the hollow portion and electrically connected to the second electrode;
An outer peripheral portion of the first electrode is supported by the joint;
The distance between the first electrode and the metal film is shorter from the center side of the hollow part toward the outer peripheral side of the hollow part,
The capacitive pressure sensor according to claim 1. The joint includes a metal member disposed on the flexible substrate side and a highly moisture-proof insulating film disposed on the hard substrate side.
The capacitance type pressure sensor according to claim 1 or 2, wherein A signal line electrically connected to the second electrode and provided on the flexible substrate;
A shield wire provided on the flexible substrate;
With
A shield line is arranged across the signal line,
The electrostatic capacity type pressure sensor according to any one of claims 1 to 3. A thermally conductive member provided on the flexible substrate and connected to the first electrode;
A temperature sensor provided on the flexible substrate and disposed in the vicinity of the thermally conductive member;
The capacitive pressure sensor according to any one of claims 1 to 4, further comprising: A shield film provided on the opposite surface of the flexible substrate facing the hard substrate;
The electrostatic capacity type pressure sensor according to any one of claims 1 to 5, wherein The first electrode and the shield film have the same potential;
The capacitive pressure sensor according to claim 6. An insulating protruding member provided in the hollow portion and disposed on the second electrode;
The electrostatic capacity type pressure sensor according to any one of claims 1 to 7, wherein The flexible substrate includes a plurality of the first electrodes,
A plurality of the second electrodes corresponding to a plurality of the first electrodes, a plurality of the hard substrates, and a plurality of the joints;
The capacitive pressure sensor according to any one of claims 1 to 8, wherein

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