WO2014141550A1

WO2014141550A1 - Capacitive pressure sensor and input device

Info

Publication number: WO2014141550A1
Application number: PCT/JP2013/082700
Authority: WO
Inventors: 井上　勝之; 敏明奥野; 古村　由幸
Original assignee: オムロン株式会社
Priority date: 2013-03-11
Filing date: 2013-12-05
Publication date: 2014-09-18
Also published as: JP2014174060A; CN105008880B; KR20150108875A; CN105008880A; KR101818315B1; JP5974939B2

Abstract

A dielectric layer (33) is formed on the top surface of a fixed electrode (32). By causing the top surface of the dielectric layer (33) to recede downwards, a recess (33a) is formed in the top surface of the dielectric layer (33). An upper substrate (35a) is layered on the top surface of the dielectric layer (33) so as to cover the recess (33a). From a part of the upper substrate (35a), specifically a region positioned above the recess (33a), a conductive diaphragm (35) having a thin film shape is formed. In the region of the dielectric layer (33) opposite of the diaphragm (35), the ratio of where the dielectric layer is present on the circular perimeter centered on said opposite region varies according to the distance from the center of the opposite region.

Description

Capacitance type pressure sensor and input device

The present invention relates to a capacitive pressure sensor and an input device. Specifically, the present invention relates to a touch-mode capacitive pressure sensor in which a diaphragm bent by pressure contacts a dielectric layer to detect pressure. The present invention also relates to an input device using the pressure sensor.

In a general capacitive pressure sensor, a conductive diaphragm (movable electrode) and a fixed electrode are opposed to each other with a gap therebetween, and a change in capacitance between the diaphragm bent by pressure and the fixed electrode. The pressure is detected from. When this pressure sensor is a micro device manufactured by MEMS technology using a glass substrate or a silicon substrate, the diaphragm may be destroyed if a large pressure is applied to the diaphragm and it bends greatly.

For this reason, a dielectric layer is provided on the surface of the fixed electrode so that the diaphragm bent by pressure comes into contact with the dielectric layer, and the capacitance between the diaphragm and the fixed electrode changes as the contact area changes. A pressure sensor has been proposed. This pressure sensor is sometimes called a touch mode capacitive pressure sensor.

An example of the touch mode capacitive pressure sensor is described in Non-Patent Document 1. FIG. 1A is a cross-sectional view showing a pressure sensor 11 described in Non-Patent Document 1. FIG. In this pressure sensor 11, a fixed electrode 13 made of a metal thin film is formed on the upper surface of a glass substrate 12. The fixed electrode 13 has a disk shape as shown in FIG. A dielectric film 14 is formed on the upper surface of the glass substrate 12 from above the fixed electrode 13. An electrode pad 16 is provided on the upper surface of the dielectric film 14. A through hole 15 is opened in the dielectric film 14, and an electrode pad 16 is connected to the fixed electrode 13 through the through hole 15. A silicon substrate 17 is laminated on the upper surface of the dielectric film 14. A recess 18 is provided on the upper surface of the silicon substrate 17, and a recess 19 is provided on the lower surface of the silicon substrate 17. A thin film diaphragm 20 is formed between the recess 18 and the recess 19. The diaphragm 20 is provided at a position overlapping the fixed electrode 13. The lower surface of the silicon substrate 17 is a P ⁺ layer 21 doped with B (boron) at a high concentration, thereby imparting conductivity to the diaphragm 20 and using the diaphragm 20 as a movable electrode. A gap 22 of several μm is formed by the recess 19 between the lower surface of the diaphragm 20 and the upper surface of the dielectric film 14.

FIG. 2 is a diagram showing the relationship between the pressure and capacitance of the pressure sensor 11 (pressure-capacitance characteristics), and is described in Non-Patent Document 1. When pressure is applied to the diaphragm 20 of the pressure sensor 11, the diaphragm 20 bends according to the applied pressure and contacts the dielectric film 14 at a certain pressure. A section (non-contact area) where the pressure is from 0 to Pa on the horizontal axis in FIG. 2 is an area where the diaphragm 20 is not in contact with the dielectric film 14. The section from the pressure Pa to Pb (contact start region) is a region from when the diaphragm 20 contacts the dielectric film 14 until it reliably contacts with a certain area. In a section (operation region) where the pressure is from Pb to Pc, the area of the portion where the diaphragm 20 is in contact with the dielectric film 14 gradually increases as the pressure increases. The section (saturation region) where the pressure is from Pc to Pd is a region where almost the entire surface of the diaphragm 20 is in contact with the dielectric film 14 and the contact area hardly increases even when the pressure increases.

According to the pressure-capacitance characteristics of FIG. 2, when the pressure increases, the change in capacitance is small in the non-contact region where the diaphragm 20 is not in contact, but gradually changes in the capacitance change rate ( (Increase rate) increases. Although the linearity is improved in the operation region, the rate of change of the capacitance gradually decreases, and the capacitance hardly increases in the saturation region.

In the pressure sensor 11 in the touch mode, the capacitance C between the diaphragm 20 and the dielectric film 14 can be expressed by the following formula 1.
C = Co + ε · (S / d) (Formula 1)
However, the contact area between the diaphragm 20 and the dielectric film 14 is represented by S, the thickness of the dielectric film 14 is represented by d, and the dielectric constant of the dielectric film 14 is represented by ε. Co is a capacitance in a non-contact region. When the pressure increases, the thickness d and the dielectric constant ε of the dielectric film 14 do not change, and the contact area S of the diaphragm 20 increases. According to Equation 1, the capacitance C of the pressure sensor 11 at this time It can be seen that increases.

However, in the case of this pressure sensor, the output characteristic indicating the relationship between the pressing force and the output cannot accurately reproduce an ideal curve indicating an ideal pressing feeling when pressing the pressure sensor. FIG. 7 is a diagram showing the relationship between the ideal curve and the output characteristics of the pressure sensor. The horizontal axis in FIG. 7 indicates the magnitude of the load (pressing force) that presses the diaphragm. The vertical axis in FIG. 7 indicates the rate of change (output ratio) of the capacitance between the diaphragm and the fixed electrode.

FIG. 8 is an enlarged view of the X section of FIG. In FIG. 7, a curve α represents an ideal curve, and a curve β represents output characteristics of a conventional example. Comparing the ideal curve α with the conventional curve β, both curves have almost the same capacitance change rate in the rising region (contact start region) when a small load is applied and in the saturation region when a large load is applied. Have However, in the middle region (operation region) of the load, the difference in output characteristics between the capacitance change rate of the conventional example and the ideal curve is large. In this pressure sensor, there is a flaw between the strength of the pressure detected by the pressure sensor and the operator's pressing feeling, and it is impossible to detect even a change in the pressing feeling of the operator. In particular, when a touch pad is configured by arranging a large number of minute pressure sensors, it is difficult to detect a change in writing pressure when a character or a figure is drawn with a finger.

Therefore, there is a demand for the development of a pressure sensor having detection characteristics or output characteristics that fits the feeling of pressing when a person presses the pressure sensor.

In Patent Document 1, by providing a gap in the fixed electrode, the area increase rate of the fixed electrode increases according to the distance from the center of the fixed electrode (therefore, the fixed electrode existence ratio also increases monotonously. .) A pressure sensor is disclosed. However, this pressure sensor is intended to improve the linearity of the amount of change in capacitance with respect to the amount of change in pressure. With the pressure sensor of Patent Document 1, it is possible to obtain characteristics close to the ideal curve described above. Can not.

JP 2006-200990 A

The present invention has been made in view of the technical background as described above, and an object of the present invention is to provide a pressure having a detection characteristic or an output characteristic that fits a person's pressing feeling when pressing the pressure sensor. It is to provide a sensor. Moreover, it is providing the input device using the said pressure sensor.

A capacitance type pressure sensor according to the present invention includes a fixed electrode, a dielectric layer formed above the fixed electrode, and a conductive diaphragm formed above the dielectric layer with a gap therebetween. And the dielectric layer has an abundance ratio of the dielectric layer on a circumference centered on the center of the opposing region in a facing region facing the diaphragm, depending on a distance from the center of the facing region. It is characterized by doing. Here, the abundance ratio of the dielectric layer is a value obtained by dividing the volume of the dielectric layer on the annular zone around the center of the opposing region by the area of the annular zone.

According to the capacitive pressure sensor of the present invention, the abundance ratio of the dielectric layer on the circumference centered on the center of the opposing region of the dielectric layer is adjusted according to the distance from the center of the opposing region. As a result, the output characteristic can be brought close to an ideal curve. Therefore, it is possible to adjust the detection characteristic or output characteristic of the pressure sensor so as to fit the human pressing feeling.

In an embodiment of the capacitive pressure sensor according to the present invention, the abundance ratio of the dielectric layer in the middle between the central portion and the outer peripheral portion of the facing region is the abundance ratio of the dielectric layer in the central portion of the facing region. It is characterized by being smaller than. In the case of the conventional example in which the dielectric is uniformly provided on the entire surface of the opposing region, the change rate of the electrostatic capacitance is larger than the ideal curve in the intermediate region between the rising region and the saturated region. On the other hand, in this embodiment, the abundance ratio of the dielectric layer in the middle between the central portion and the outer peripheral portion of the opposing region is smaller than the abundance ratio of the dielectric layer in the central portion of the opposing region. Output can be reduced, and the output characteristics can be made closer to an ideal curve.

However, if the ratio of the dielectric layer existing between the central portion and the outer peripheral portion of the opposing region is reduced, the output in the saturation region of the output characteristics also decreases accordingly, and the output may be smaller than the ideal curve. . In that case, if the abundance ratio of the dielectric layer in the outer peripheral portion of the opposing region is larger than the abundance ratio of the dielectric layer in the middle between the central portion and the outer peripheral portion of the opposing region, the saturation region of the output characteristics The value at can be increased to approach the ideal curve again.

Also, if the abundance ratio of the dielectric layer in the outer peripheral portion of the opposing region is made smaller than the abundance ratio of the dielectric layer in the central portion of the opposing region, the value in the saturation region of the output characteristics will increase. It can be prevented from being too much.

In another embodiment of the capacitive pressure sensor according to the present invention, an opening is provided in the dielectric layer in the facing region, and a ratio of the opening is changed according to a distance from a center of the facing region. It is characterized in that the abundance ratio of the dielectric layer is changed. According to this embodiment, for example, after the dielectric layer having a constant thickness is formed in the facing region, the abundance ratio of the dielectric layer can be changed by opening the dielectric layer. In this case, it is preferable that the openings of the dielectric layer are formed radially from the center of the facing region. By forming the openings radially, it is possible to prevent the dielectric layer or the openings from being biased in a specific direction.

Further, in order to change the abundance ratio of the dielectric layer, the thickness of the dielectric layer may be changed in the facing region according to the distance from the center of the facing region.

In still another embodiment of the capacitive pressure sensor according to the present invention, the facing region is divided into a plurality of sections according to the distance from the center, and the abundance ratio of the dielectric layer is made constant in each section. It is characterized by that. According to such an embodiment, design can be facilitated because the abundance ratio of the dielectric layer may be adjusted for each section.

The input device according to the present invention is characterized in that a plurality of capacitive pressure sensors according to the present invention are arranged. Since the input device of the present invention uses the capacitive pressure sensor according to the present invention, it is possible to detect the pressing position and the pressing force. Moreover, it is possible to detect a change in writing pressure when a character or figure is drawn with a finger or the like.

The means for solving the above-described problems in the present invention has a feature in which the above-described constituent elements are appropriately combined, and the present invention enables many variations by combining such constituent elements. .

FIG. 1A is a schematic cross-sectional view showing a pressure sensor according to a conventional example. FIG. 1B is a plan view showing a fixed electrode formed on the upper surface of the glass substrate in the pressure sensor of FIG. FIG. 2 is a diagram showing the relationship between pressure and capacitance in the conventional pressure sensor shown in FIG. FIG. 3A is a plan view showing the pressure sensor according to the first embodiment of the present invention. FIG. 3B is a plan view showing a dielectric layer formed on the upper surface of the fixed electrode in the pressure sensor shown in FIG. FIG. 4 is a cross-sectional view of the pressure sensor shown in FIG. FIG. 5 is a diagram showing the relationship between the radial distance from the center of the diaphragm and the abundance ratio of the dielectric layer in the dielectric film of FIG. FIG. 6 is a diagram for explaining the definition of the abundance ratio of the dielectric layer. FIG. 7 is a diagram showing the relationship (output characteristics) between the load (pressing force) applied to the diaphragm and the capacitance change rate between the diaphragm and the fixed electrode. FIG. 8 is an enlarged view of the X section of FIG. FIG. 9 is a diagram showing the ratio of deviation from the ideal curve in the conventional example and the embodiment of the present invention. FIG. 10 is a plan view showing a modification of the pressure sensor according to Embodiment 1 of the present invention. FIG. 11 is a cross-sectional view of a pressure sensor according to Embodiment 2 of the present invention. FIG. 12 is a cross-sectional view of an input device according to Embodiment 3 of the present invention.

31, 51 Pressure sensor 32 Fixed electrode 33 Dielectric layer 33a Recess 34 Air gap 35 Diaphragm 37 Upper surface electrode 39 Opening 40 Electrode pad 41 Protective film 61 Input device

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments, and various design changes can be made without departing from the gist of the present invention.

(Embodiment 1)
The structure of the pressure sensor 31 according to the first embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIG. 3A is a plan view of the pressure sensor 31. FIG. 3B is a plan view of the state in which the upper substrate 35 a is removed from the pressure sensor 31 of FIG. 3A, and shows the dielectric layer 33 formed on the upper surface of the fixed electrode 32. FIG. 4 is a cross-sectional view of the pressure sensor 31.

In the pressure sensor 31, as shown in FIG. 4, a dielectric layer 33 is formed on a fixed electrode 32 made of a conductive material such as a low-resistance silicon substrate or a metal film. The dielectric layer 33 is made of a dielectric material such as SiO ₂ (thermal oxide film), SiN, or TEOS. A recess 33a (circular recess) is provided in the center of the upper surface of the dielectric layer 33. That is, the thickness of the dielectric layer 33 is thick outside the recess 33a, and the thickness of the dielectric layer 33 is thin inside the recess 33a. The dielectric layer 33 in the recess 33a has a certain thickness.

On the upper surface of the dielectric layer 33, a thin film upper substrate 35a made of a conductive material such as a low resistance silicon substrate is formed. The upper substrate 35a covers the upper surface of the recess 33a, and an air gap 34 (air gap) is formed between the lower surface of the upper substrate 35a and the recess bottom surface of the dielectric layer 33 by the recess 33a. Thus, a pressure-sensitive diaphragm 35 is formed by a region of the upper substrate 35a that is horizontally stretched above the air gap 34. The dielectric layer 33 located on the bottom surface in the recess 33 a is a facing region facing the diaphragm 35.

The dielectric layer 33 is provided with a vent line 36 (air passage) to ensure air permeability between the air gap 34 and the outside. The vent line 36 is a narrow groove having a width of about 30 μm, and is bent or meandering so that foreign matters such as dust and dirt do not easily enter the air gap 34.

As shown in FIG. 3 (B), the dielectric layer 33 has a plurality of sections (here, three sections) along the radial direction from the center of the counter area (center of the counter area) in the counter area in the recess 33a. Sections I, II, and III). Section I is a circular area located at the center of the opposing area. A dielectric layer 33 is formed on the entire surface of the section I. Section III is an annular region located on the outer periphery of the opposing region. In the section III, a plurality of openings 39 are provided radially and at equal intervals. Section II is an annular region located in the middle between the central portion and the outer peripheral portion of the opposing region. In the section II, a plurality of openings 39 are provided radially and at equal intervals. The fixed electrode 32 is exposed in each opening 39 provided in the dielectric layer 33. In FIG. 3B, a region with a dot pattern is a region where the dielectric layer 33 is formed. The white area in FIG. 3B is an area where the fixed electrode 32 is exposed.

FIG. 5 is a diagram showing the abundance ratio of the dielectric layer 33 in the facing region. The horizontal axis in FIG. 5 indicates the radius (radial distance) measured from the center of the opposing region (or diaphragm 35) of the dielectric layer 33. However, the distance on the horizontal axis in FIG. 5 is expressed as a ratio with the radius from the center to the outer periphery of the facing region being 100. The vertical axis in FIG. 5 represents the abundance ratio of the dielectric layer 33. The abundance ratio of the dielectric layer 33 at the position of the radius r centering on the center C (center) of the opposing region is
V / (2πr · δr)
Defined by Here, as shown in FIG. 6, the symbol V indicates a dielectric layer 33 existing on the annular zone when the annular zone having the radius r and the width δr around the center C (center) of the opposing region is considered. Represents the volume of. 2πr · δr is the area of the annular zone. δr is set to a sufficiently small value. Therefore, the larger the area of the dielectric layer 33 existing on the annular zone (the smaller the area of the opening 39), the greater the abundance ratio of the dielectric layer 33. Further, the larger the thickness of the dielectric layer 33 existing on the annular zone, the larger the abundance ratio of the dielectric layer 33. However, on the vertical axis in FIG. 5, the existence ratio of the dielectric layer 33 in the section I is assumed to be 100 (%), and the ratio is displayed.

Since section II has an opening 39, the abundance ratio of dielectric layer 33 in section II is smaller than the abundance ratio of dielectric layer 33 in section I as shown in FIG. Since the ratio of the opening 39 is smaller in the section III than in the section II, the abundance ratio of the dielectric layer 33 in the section III is larger than the abundance ratio of the dielectric layer 33 in the section II, and the dielectric ratio in the section I is It is smaller than the abundance ratio of the body layer 33.

An annular upper electrode 37 made of a metal material is provided on the upper surface of the upper substrate 35a so as to surround the diaphragm 35. Electrode pads 40 are provided at the corners of the upper substrate 35a. The upper surface electrode 37 and the electrode pad 40 are connected by the wiring part 42. The upper surface electrode 37, the wiring portion 42, and the electrode pad 40 are simultaneously formed by a two-layer metal thin film of a base layer Ti (thickness 1000 mm) / surface layer Au (thickness 3000 mm). A lower surface electrode 38 is provided on the lower surface of the fixed electrode 32. The bottom electrode 38 is also made of a two-layered metal thin film of base layer Ti (thickness 1000 mm) / surface layer Au (thickness 3000 mm).

A region outside the upper surface electrode 37 on the upper surface of the upper substrate 35a is covered with a protective film 41 made of a resin such as polyimide or an insulating film such as SiO ₂ or SiN. However, the protective film 41 is removed in the vicinity of the electrode pad 40, and the electrode pad 40 is exposed from the protective film 41.

FIG. 7 is a diagram showing the rate of change of capacitance. FIG. 7 shows an ideal curve (target capacitance change rate) (α), a capacitance change rate (β) in a conventional pressure sensor, and a static value in a pressure sensor according to an embodiment of the present invention. The rate of change in capacitance (γ) is shown. FIG. 8 is an enlarged view of the X section of FIG. 7 in the horizontal axis direction.

The capacitance change rate ΔC / Co shown on the vertical axis in FIG. 7 is defined as follows. The capacitance between the diaphragm deflected by the load and the fixed electrode is C, and the capacitance between the diaphragm and the fixed electrode when the diaphragm is not bent is Co. The capacitance change rate ΔC / Co is the ratio of the capacitance change ΔC = C−Co to the capacitance Co,
ΔC / Co = (C-Co) / Co
It is represented by

When a person presses an object, for example, the pressure strength felt at the fingertip is not necessarily proportional to the magnitude of the load. I don't feel the difference in size. The ideal curve represents a feeling of pressing when the person presses the pressure sensor (how to feel the pressing strength) as an output of the pressure sensor.

In the region where the capacitance change rate in FIG. 7 is almost zero, the region in which the diaphragm is bent without contacting the dielectric layer (dielectric film) (non-contact region) and the capacitance change rate are rapidly increased. It is the area (contact start area) that stands up. In the non-contact area and the contact start area, the difference between the output characteristics of the conventional example and the ideal curve is small. Accordingly, also in the embodiment of the present invention, in the region corresponding to the contact start region (section I), the dielectric layer is formed on the entire surface as in the conventional example.

On the other hand, in the region where the area where the diaphragm contacts the dielectric layer is gradually increased (operation region), the output characteristic of the conventional example has a value larger than the ideal curve. Therefore, in the embodiment of the present invention, the existence ratio of the dielectric layer is reduced in the region corresponding to the operation region (section II), thereby reducing the output characteristics and approaching the ideal curve.

¡In the region where the contact area hardly changes even when the load increases (saturation region) because most of the diaphragm is in contact with the dielectric layer, the deviation from the ideal curve is small even in the output characteristics of the conventional example. However, in the embodiment of the present invention, the value of the output characteristic is lowered by reducing the existence ratio of the dielectric layer in the section II. Therefore, in the embodiment of the present invention, in the region corresponding to the saturation region (section III), the abundance ratio of the dielectric layer is made larger than in section II, thereby increasing the output characteristics in section III and not deviating from the ideal curve. I am doing so.

As a result, according to the embodiment of the present invention, output characteristics close to an ideal curve can be obtained. FIG. 9 shows the ratio of deviation from the ideal curve in the conventional example and the embodiment of the present invention. Here, when the electrostatic capacity in the ideal curve at a certain load is Cr and the electrostatic capacity in the conventional example is Cc, the maximum value [%] of 100 × (Cc-Cr) / Cr is the ideal curve in the conventional example. It is called the ratio of deviation. Similarly, when the electrostatic capacity in an ideal curve at a certain load is Cr, and the electrostatic capacity of the embodiment of the present invention is Cp, the maximum value [%] of 100 × (Cp−Cr) / Cr is the present invention. This is called the ratio of deviation from the ideal curve of the embodiment. As can be seen from FIG. 9, in the case of the conventional example, the rate of deviation from the ideal curve is about 6.6%, whereas in the embodiment of the present invention, the rate of deviation from the ideal curve is 2.0%. It is getting smaller. Therefore, according to the embodiment of the present invention, the detection characteristic or the output characteristic of the pressure sensor can be adjusted to fit a human pressing feeling.

The upper surface electrode 37 may not be annular, and a plurality of arc-shaped upper surface electrodes 37 may be provided (not shown). Further, the upper surface electrode 37 may not be provided. This is because the upper substrate 35a has conductivity, and therefore it is only necessary to provide the electrode pad 40 at least at one location on the upper substrate 35a outside the area of the diaphragm 35 as shown in FIG.

(Embodiment 2)
FIG. 11 is a cross-sectional view of a pressure sensor 51 according to Embodiment 2 of the present invention.
In this pressure sensor 51, the opening 39 is not provided in the dielectric layer 33, but the thickness of the dielectric layer 33 is changed according to the radius (distance) from the center of the opposing region. Thereby, the abundance ratio of the dielectric layer 33 is changed according to the radius from the center of the opposing region. In particular, in the case of FIG. 11, the facing region is divided into three sections I, II, and III, and the thickness of the dielectric layer 33 in the section II is made thinner than the thickness of the dielectric layer 33 in the section I. Further, the thickness of the dielectric layer 33 in the section III is larger than the thickness of the dielectric layer 33 in the section II and is smaller than the thickness of the dielectric layer 33 in the section I. Even in such an embodiment, the same effects as those of the first embodiment can be achieved.

In each of the above embodiments, the opposing region is divided into three sections and the pattern of the dielectric layer 33 or the existence ratio of the dielectric layer 33 is changed. However, the opposing area is divided into four or more sections. The pattern of the layer 33 or the existence ratio of the dielectric layer 33 may be changed.

(Embodiment 3)
FIG. 12 is a cross-sectional view showing the structure of a plate-type input device 61, for example, a touch panel, according to Embodiment 3 of the present invention. The input device 61 includes a large number of pressure sensors 31 (sensor units) according to the first embodiment arranged in an array (for example, a rectangular shape or a honeycomb shape). Each pressure sensor 31 is electrically independent, and the pressure applied to each pressure sensor 31 can be detected independently. According to such an input device 61, it is possible to detect a point pressed by a pressing body such as a touch panel, and it is also possible to detect a pressing strength (a magnitude of pressure) of each point.

Claims

A fixed electrode;
A dielectric layer formed above the fixed electrode;
A conductive diaphragm formed above the dielectric layer with a gap therebetween;
With
In the facing region of the dielectric layer facing the diaphragm, the abundance ratio of the dielectric layer on the circumference centered on the center of the facing region changes according to the distance from the center of the facing region. Capacitance type pressure sensor.
2. The static electricity according to claim 1, wherein an abundance ratio of the dielectric layer in the middle between the central portion and the outer peripheral portion of the opposing region is smaller than an abundance ratio of the dielectric layer in the central portion of the opposing region. Capacitive pressure sensor.
3. The static electricity according to claim 2, wherein an abundance ratio of the dielectric layer in an outer peripheral portion of the facing region is larger than an abundance ratio of the dielectric layer in the middle between the central portion and the outer peripheral portion of the facing region. Capacitive pressure sensor.
4. The capacitance type pressure sensor according to claim 3, wherein an abundance ratio of the dielectric layer in an outer peripheral portion of the facing area is smaller than an abundance ratio of the dielectric layer in a central portion of the facing area.
Providing an opening in the dielectric layer in the facing region;
The capacitance type pressure sensor according to claim 1, wherein the presence ratio of the dielectric layer is changed by changing the ratio of the openings according to the distance from the center of the facing region.
6. The capacitive pressure sensor according to claim 5, wherein the openings of the dielectric layer are formed radially with the center of the opposing region as a center.
The static ratio according to claim 1, wherein the abundance ratio of the dielectric layer is changed by changing a thickness of the dielectric layer according to a distance from a center of the opposing region in the opposing region. Capacitive pressure sensor.
The capacitive pressure sensor according to claim 1, wherein the facing region is divided into a plurality of sections according to a distance from a center thereof, and the existence ratio of the dielectric layer is made constant in each section. .
An input device in which a plurality of the capacitive pressure sensors according to claim 1 are arranged.