阅读说明：本技术 压力传感器 (Pressure sensor ) 是由 丹羽亮介 吉田康一 于 2020-02-27 设计创作，主要内容包括：压力传感器(10)具有：基座基板(12)；第1绝缘层(14),其设于基座基板(12)；固定电极(16),其设于第1绝缘层(14)；侧壁部(18),其设于第1绝缘层(14),包围固定电极(16)；以及膜片(20),其具备导电性,与固定电极(16)空开间隔地相对,并且支承于侧壁部(18)。侧壁部(18)包括配置于第1绝缘层(14)上的屏蔽电极(24)和配置于屏蔽电极(24)上的第2绝缘层(26)。固定电极(16)与膜片(20)之间的距离(L1)比屏蔽电极(24)与膜片(20)之间的距离(L2)小。(A pressure sensor (10) is provided with: a base substrate (12); a 1 st insulating layer (14) provided on the base substrate (12); a fixed electrode (16) provided on the 1 st insulating layer (14); a side wall portion (18) provided on the 1 st insulating layer (14) and surrounding the fixed electrode (16); and a diaphragm (20) which has conductivity, faces the fixed electrode (16) with a gap, and is supported by the side wall (18). The side wall portion (18) includes a shield electrode (24) disposed on the 1 st insulating layer (14) and a 2 nd insulating layer (26) disposed on the shield electrode (24). A distance (L1) between the fixed electrode (16) and the diaphragm (20) is smaller than a distance (L2) between the shield electrode (24) and the diaphragm (20).)

1. A pressure sensor, wherein,

the pressure sensor includes:

a base substrate;

a 1 st insulating layer provided on the base substrate;

a fixed electrode provided on the 1 st insulating layer;

a sidewall portion provided on the 1 st insulating layer and surrounding the fixed electrode; and

a diaphragm having conductivity, facing the fixed electrode with a space therebetween, and supported by the side wall portion,

the sidewall portion includes a shield electrode disposed on the 1 st insulating layer and a 2 nd insulating layer disposed on the shield electrode,

the distance between the fixed electrode and the diaphragm is smaller than the distance between the shielding electrode and the diaphragm.

2. The pressure sensor of claim 1,

the surface of the diaphragm on the base substrate side has a multi-step structure including at least a 1 st step surface and a 2 nd step surface, the 1 st step surface facing the fixed electrode, the 2 nd step surface being provided so as to surround the 1 st step surface when viewed from a facing direction of the fixed electrode and the diaphragm and supported by the side wall portion,

the 2 nd step surface is farther from the base substrate than the 1 st step surface.

3. The pressure sensor of claim 2,

the side wall portion is a frame shape having an outer shape in a rectangular shape in a longitudinal direction and a width direction when viewed from the opposing direction,

the 1 st step surface of the diaphragm has a shape that narrows in at least one of the longitudinal direction and the width direction when viewed from the opposing direction.

4. The pressure sensor according to any one of claims 1 to 3,

at least a central portion of the fixed electrode has a thickness greater than a thickness of the shielding electrode.

5. The pressure sensor according to any one of claims 1 to 4,

a dielectric layer is provided on a surface of the fixed electrode facing the diaphragm.

Technical Field

The present invention relates to a pressure sensor for measuring pressure such as air pressure.

Background

For example, as described in patent document 1, a capacitance type pressure sensor includes: a planar base (base substrate); an insulating layer provided on the substrate; an internal electrode layer (fixed electrode) provided on the insulating layer; a frame-shaped sidewall portion provided on the insulating layer so as to surround the fixed electrode; and a diaphragm plate (diaphragm) which faces the fixed electrode with a space. The diaphragm is supported by the sidewall portion. The pressure acting on the diaphragm is detected (calculated) based on the electrostatic capacitance between the diaphragm and the fixed electrode.

In the case of the capacitance-type pressure sensor described in patent document 1, the side wall portion is composed of a shield electrode provided on the insulating layer and an insulating layer provided on the diaphragm side of the shield electrode. With this shield electrode, the influence of electrostatic capacitance (parasitic capacitance) at the side wall portion is reduced. As a result, the sensing sensitivity is improved, and the linearity of the change in the electrostatic capacitance with respect to the change in the pressure is improved.

Documents of the prior art

Patent document

Patent document 1: japanese Kohyo publication (Kokai) No. 2017-506329

Disclosure of Invention

Problems to be solved by the invention

However, in the case of the capacitance type pressure sensor described in patent document 1, a drive current supplied to the sensor for driving the sensor flows to the capacitance between the fixed electrode and the diaphragm, and also flows to the capacitance between the shield electrode and the diaphragm. That is, a part of the electric power supplied to the pressure sensor is consumed without being used for sensing.

In order to cope with this, it is considered that the distance between the shield electrode and the diaphragm is increased by increasing the thickness of the insulating layer at the side wall portion, thereby reducing the electrostatic capacitance between the shield electrode and the diaphragm. However, the capacitance type sensor described in patent document 1 includes a configuration in which the distance between the shield electrode and the diaphragm is the same as the distance between the fixed electrode and the diaphragm. Therefore, if the thickness of the insulating layer at the side wall portion is increased, the distance between the fixed electrode and the diaphragm is also increased. As a result, the capacitance between the fixed electrode and the diaphragm is also reduced, and the sensing sensitivity is lowered.

Accordingly, the present invention has been made in view of the above problems, and an object thereof is to suppress power consumption due to electrostatic capacitance between a shield electrode and a diaphragm without reducing sensing sensitivity in an electrostatic capacitance type pressure sensor having a structure in which a side wall portion of a support diaphragm includes the shield electrode.

Means for solving the problems

In order to solve the above-described problem, according to an aspect of the present invention, there is provided a pressure sensor including:

a base substrate;

a 1 st insulating layer provided on the base substrate;

a fixed electrode provided on the 1 st insulating layer;

a sidewall portion provided on the 1 st insulating layer and surrounding the fixed electrode; and

a diaphragm having conductivity, facing the fixed electrode with a space therebetween, and supported by the side wall portion,

the sidewall portion includes a shield electrode disposed on the 1 st insulating layer and a 2 nd insulating layer disposed on the shield electrode,

the distance between the fixed electrode and the diaphragm is smaller than the distance between the shielding electrode and the diaphragm.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, in the capacitance type pressure sensor of the configuration in which the side wall portion of the support diaphragm includes the shield electrode, it is possible to suppress power consumption generated by the electrostatic capacitance between the shield electrode and the diaphragm without lowering the sensing sensitivity.

Drawings

Fig. 1 is a perspective view of a pressure sensor according to embodiment 1 of the present invention.

Fig. 2 is an exploded perspective view of a pressure sensor according to embodiment 1 of the present invention.

Fig. 3 is a sectional view of the pressure sensor according to embodiment 1 of the present invention.

Fig. 4 is a diagram showing an example of connection between the pressure sensor and the inverting amplifier circuit.

Fig. 5 is an exploded perspective view of a pressure sensor according to embodiment 2 of the present invention.

Fig. 6 is a diagram showing the surface of the base substrate side of the diaphragm of the pressure sensor according to embodiment 2 of the present invention.

Fig. 7 is a sectional view of a pressure sensor according to embodiment 3 of the present invention.

Fig. 8 is a sectional view of a pressure sensor according to another embodiment of the present invention.

Fig. 9 is a diagram showing a surface of a base substrate side of a diaphragm of a pressure sensor according to a different embodiment of the present invention.

Fig. 10 is a diagram showing a surface of a base substrate side of a diaphragm of a pressure sensor according to another different embodiment of the present invention.

Detailed Description

A pressure sensor according to an aspect of the present invention includes: a base substrate; a 1 st insulating layer provided on the base substrate; a fixed electrode provided on the 1 st insulating layer; a sidewall portion provided on the 1 st insulating layer and surrounding the fixed electrode; and a diaphragm having conductivity, facing the fixed electrode with a space therebetween, and supported by the side wall portion, wherein the side wall portion includes a shield electrode disposed on the 1 st insulating layer and a 2 nd insulating layer disposed on the shield electrode, and a distance between the fixed electrode and the diaphragm is smaller than a distance between the shield electrode and the diaphragm.

According to this aspect, in the capacitance type pressure sensor having the structure in which the side wall portion of the support diaphragm includes the shield electrode, power consumption due to capacitance between the shield electrode and the diaphragm can be suppressed without lowering the sensing sensitivity.

For example, the surface of the diaphragm on the base substrate side may have a multi-step structure including at least a 1 st step surface and a 2 nd step surface, the 1 st step surface facing the fixed electrode, the 2 nd step surface being provided so as to surround the 1 st step surface when viewed from a facing direction of the fixed electrode and the diaphragm and supported by the side wall portion, and the 2 nd step surface being located farther from the base substrate than the 1 st step surface.

For example, the side wall portion may have a frame shape having an outer shape in a rectangular shape in a longitudinal direction and a width direction when viewed from the opposing direction, and the 1 st step surface of the diaphragm may have a shape narrowing in at least one of the longitudinal direction and the width direction when viewed from the opposing direction. Thus, even if the pressure sensor continues to receive an external force such as a compressive force and both end portions in the longitudinal direction of the diaphragm are maintained in a deformed state, deformation of the 1 st step surface facing the fixed electrode can be suppressed.

For example, at least a central portion of the fixed electrode may have a thickness larger than a thickness of the shield electrode.

For example, a dielectric layer may be provided on a surface of the fixed electrode facing the diaphragm. This enables the pressure sensor to be used as a touch mode pressure sensor.

Embodiments of the present invention will be described below with reference to the drawings.

(embodiment mode 1)

Fig. 1 is a perspective view of a pressure sensor of embodiment 1 of the present invention, fig. 2 is an exploded perspective view thereof, and fig. 3 is a sectional view thereof. In addition, the X-Y-Z orthogonal coordinate system shown in the drawings is used for easy understanding of the present invention, and is not intended to limit the present invention.

As shown in fig. 1 to 3, a pressure sensor 10 according to embodiment 1 is a capacitance-type pressure sensor, and includes: a base substrate 12; a 1 st insulating layer 14 provided on the base substrate 12; a fixed electrode 16 provided on the 1 st insulating layer 14; a frame-shaped sidewall 18 provided on the 1 st insulating layer 14 so as to surround the fixed electrode 16; and a diaphragm 20 supported by the side wall portion 18.

The base substrate 12 is a substrate made of an insulating material and including a conductor pattern, an external connection terminal (not shown), and the like. In embodiment 1, the base substrate 12 is a silicon substrate.

The 1 st insulating layer 14 is a layer made of an insulating material, and is provided on the base substrate 12 so as to cover the surface of the base substrate 12 on the diaphragm 20 side. In embodiment 1, the 1 st insulating layer 14 is silicon oxide (SiO) produced by thermally oxidizing the surface of the base substrate 12 as a silicon substrate₂) And (3) a membrane.

The fixed electrode 16 is an electrode made of a conductive material, and is provided on the 1 st insulating layer 14. In the case of embodiment 1, the fixed electrode 16 is made of conductive polysilicon. The fixed electrode 16 is electrically connected to the conductor pattern on the base substrate 12 via a via conductor 22 penetrating the 1 st insulating layer 14.

The side wall portion 18 is a frame-shaped member provided on the 1 st insulating layer 14, and is provided on the 1 st insulating layer 14 so as to surround the fixed electrode 16 when viewed in the facing direction (Z-axis direction) of the fixed electrode 16 and the diaphragm 20. A space is provided between the side wall portion 18 and the fixed electrode 16. In embodiment 1, the side wall 18 has a rectangular outer shape when viewed from the opposing direction of the fixed electrode 16 and the diaphragm 20.

The side wall 18 supports the diaphragm 20 such that the fixed electrode 16 faces the diaphragm 20 with a gap. That is, the thickness of the sidewall portion 18 from the 1 st insulating layer 14 is larger than the thickness of the fixed electrode 16.

The diaphragm 20 is a flexible thin plate-like member made of a conductive material. In the case of embodiment 1, the diaphragm 20 is made of conductive silicon. In addition, the diaphragm 20 includes a pressure receiving surface 20a on which a pressure of the sensing object acts. Due to the pressure acting on the pressure receiving surface 20a, the diaphragm portion 20b, which is a portion of the diaphragm 20 not supported by the side wall portion 18, is displaced toward the fixed electrode 16.

Also, the side wall portion 18 includes a shield electrode 24 and a 2 nd insulating layer 26.

The shielding electrode 24 is disposed on the 1 st insulating layer 14. The shield electrode 24 is a frame-shaped electrode made of a conductive material. In embodiment 1, the conductive polysilicon is used as the fixed electrode 16.

In embodiment 1, the shield electrode 24 is produced in the same process as the fixed electrode 16. Specifically, a polysilicon film is formed over the entire 1 st insulating layer 14. An annular groove is formed in the polysilicon film by etching or the like, and the polysilicon film is processed into the fixed electrode 16 and the shield electrode 24 surrounding the fixed electrode 16. Thus, the thickness of the fixed electrode 16 is the same as the thickness of the shield electrode 24. The function of the shield electrode 24 will be described later.

The 2 nd insulating layer 26 is disposed on the shield electrode 24 and supports the diaphragm 20. The 2 nd insulating layer 26 is a layer made of an insulating material. In the case of embodiment 1, the 2 nd insulating layer 26 is silicon oxide (SiO) formed by performing thermal oxidation treatment on the diaphragm 20 made of conductive silicon₂) And (3) a membrane.

In embodiment 1, as shown in fig. 2, the pressure sensor 10 is fabricated by bonding the diaphragm 20 provided with the 2 nd insulating layer 26 to the base substrate 12 provided with the 1 st insulating layer 14, the fixed electrode 16, and the shield electrode 24. They are joined, for example, by fusion bonding.

Fig. 4 is a diagram showing an example of connection between the pressure sensor and the inverting amplifier circuit.

As shown in fig. 4 as an example, the pressure sensor 10 is connected to, for example, the inverting amplifier circuit 30 for use. Specifically, the inverting amplifier circuit 30 is constituted by an amplifier 32 and a feedback circuit 34. The fixed electrode 16 is connected to the inverting input terminal of the amplifier 32. The feedback circuit 34 is, for example, a resistor having a predetermined impedance. The diaphragm 20 is connected to a power source 36. The non-inverting input terminal of the amplifier 32 and the shielding electrode 24 are grounded.

With such a circuit configuration, the pressure applied to the pressure receiving surface 20a of the diaphragm 20, that is, the voltage Vout corresponding to the distance between the fixed electrode 16 and the diaphragm 20 is output from the inverting amplifier circuit 30. When the pressure applied to the pressure receiving surface 20a changes, the distance between the fixed electrode 16 and the diaphragm 20 changes, and the electrostatic capacitance between them changes. The output voltage Vout of the inverting amplifier circuit 30 changes in accordance with the change in the capacitance. Therefore, the pressure acting on the pressure receiving surface 20a of the diaphragm 20 can be calculated based on the output voltage Vout of the inverting amplifier circuit 30.

The inverting amplifier circuit 30 may be incorporated in the pressure sensor 10, or may be provided on a substrate on which the pressure sensor 10 is mounted.

In such a circuit configuration, the shield electrode 24 reduces the influence of electrostatic capacitance (parasitic capacitance) at the side wall portion 18, that is, the influence on the sensing performance of the pressure sensor 10.

Specifically, the electrostatic capacitance at the side wall portion 18 exists in parallel with the electrostatic capacitance between the fixed electrode 16 and the diaphragm 20. Since the side wall portion 18 is in contact with the surrounding environment of the pressure sensor 10, the capacitance at the side wall portion 18 is likely to vary depending on the change in the surrounding environment. When the capacitance of the side wall portion 18 varies, the capacitance between the fixed electrode 16 and the diaphragm 20 is affected. As a result, the pressure sensor 10 has an influence on the sensing performance associated with the electrostatic capacitance between the fixed electrode 16 and the diaphragm 20, for example, linearity of the change in electrostatic capacitance with respect to the sensing sensitivity and the change in pressure.

In response to this, the side wall portion 18 is provided with a grounded shield electrode 24. As a result, a change in the electrostatic capacitance at the side wall portion 18 is suppressed, the sensing sensitivity of the pressure sensor 10 is improved, and the linearity of the change in the electrostatic capacitance with respect to the change in pressure is improved.

However, when the shield electrode 24 is provided on the side wall portion 18, the power consumption of the pressure sensor 10 increases.

Specifically, as shown in fig. 4, a capacitance C1 is formed between the fixed electrode 16 and the diaphragm 20, and a capacitance C2 is also formed between the shield electrode 24 and the diaphragm 20. Therefore, the current supplied from the power supply 36 flows to the capacitance C1 and flows to the capacitance C2. That is, a part of the electric power supplied from the power supply 36 to the pressure sensor 10 does not contribute to sensing, but is charged and consumed to the electrostatic capacitance C2.

In order to suppress power consumption generated in the electrostatic capacitance C2, in the pressure sensor 10, as shown in fig. 3, a distance L1 between the fixed electrode 16 and the diaphragm 20 is smaller than a distance L2 between the shield electrode 24 and the diaphragm 20.

Therefore, in embodiment 1, as shown in fig. 3, the surface 20c of the diaphragm 20 on the base substrate 12 side (i.e., the surface opposite to the pressure receiving surface 20 a) has a multi-step structure. Specifically, the surface 20c of the diaphragm 20 having the multi-step structure includes a 1 st step surface 20d facing the fixed electrode 16 and a 2 nd step surface 20e supported by the side wall portion 18. In addition, the 2 nd step surface 20e surrounds the 1 st step surface 20d when viewed from the opposing direction (Z-axis direction) of the fixed electrode 16 and the diaphragm 20. The 2 nd step surface 20e is located at a greater distance from the base substrate 12 than the 1 st step surface 20 d. The 1 st step surface 20d has a rectangular shape when viewed from the opposing direction (Z-axis direction) of the fixed electrode 16 and the diaphragm 20.

According to the multi-step structured surface 20c of the diaphragm 20, a distance L1 between the fixed electrode 16 and the diaphragm 20 (i.e., the 1 st step surface 20d) is smaller than a distance L2 between the shield electrode 24 and the diaphragm 20 (i.e., the 2 nd step surface 20 e). That is, as compared with the case where the distance L1 is the same as the distance L2, the electrostatic capacitance C1 between the fixed electrode 16 and the diaphragm 20 is larger than the electrostatic capacitance C2 between the shield electrode 24 and the diaphragm 20. Thus, as compared with the case where the distance L1 is the same as the distance L2, the amount of current from the power supply 36 flowing to the capacitor C2 decreases, and the amount of current flowing to the capacitor C1 increases. As a result, in comparison with the case where the distance L1 is the same as the distance L2, the electrostatic capacitance C2 between the shield electrode 24 and the diaphragm 20 is suppressed from being consumed. At the same time, the sensing sensitivity of the pressure sensor 10 is improved.

According to embodiment 1 as described above, in the capacitance type pressure sensor 10 having the structure in which the side wall portion 18 of the support diaphragm 20 includes the shield electrode 24, it is possible to suppress power consumption occurring in the capacitance C2 between the shield electrode 24 and the diaphragm 20 without lowering the sensing sensitivity.

(embodiment mode 2)

Embodiment 2 is a modification of embodiment 1 described above. Therefore, in the pressure sensor of embodiment 2, substantially the same components as those of the pressure sensor 10 of embodiment 1 described above are denoted by the same reference numerals. The pressure sensor according to embodiment 2 will be described focusing on differences from embodiment 1 described above.

Fig. 5 is an exploded perspective view of a pressure sensor according to embodiment 2 of the present invention. Fig. 6 is a diagram showing the surface of the base substrate side of the diaphragm of the pressure sensor according to embodiment 2 of the present invention.

As shown in fig. 2, in the pressure sensor 10 according to embodiment 1 described above, the 1 st step surface 20d of the diaphragm 20 has a rectangular shape when viewed from the opposing direction (Z-axis direction) between the fixed electrode 16 and the diaphragm 20. However, as shown in fig. 5 and 6, the 1 st step surface 120d of the diaphragm 120 of the pressure sensor 110 according to embodiment 2 is a shape narrowed in the longitudinal direction (X-axis direction) when viewed from the opposing direction (Z-axis direction) of the fixed electrode 16 and the diaphragm 120, that is, a shape having narrowed portions 120f at both ends in the longitudinal direction.

As shown in fig. 5, in the pressure sensor 110 according to embodiment 2, the ratio of the dimension in the longitudinal direction (X-axis direction) to the dimension in the width direction (Y-axis direction) is larger than that of the pressure sensor 10 according to embodiment 1. In the case of such a pressure sensor 110, when an external force is applied, a part of the diaphragm portion 120b of the diaphragm 120 is easily deformed. For example, when the pressure sensor 110 is embedded in a resin package in a state where the diaphragm portion 120b is exposed to the outside and protected, the pressure sensor 110 continues to receive a compressive stress as an external force due to the hardening (i.e., shrinkage) of the resin package. In this case, as shown by cross hatching in fig. 6, both end portions in the longitudinal direction of the diaphragm portion 120b are maintained in a deformed state. The degree and form of the deformation differ for each of the plurality of pressure sensors 110 manufactured. As a result, in the plurality of pressure sensors 110, the distance between each of the opposite end portions of the diaphragm portion 120b and the fixed electrode 16 varies, and thus the sensing performance also varies.

To cope with this, as shown in fig. 6, the 1 st step surface 120d has a shape narrowed in the longitudinal direction in order to avoid both end portions (cross hatching) in the longitudinal direction (X-axis direction) of the diaphragm portion 120b which are likely to be deviated (the degree of deviation exceeds an allowable limit) depending on the distance from the fixed electrode 16. This suppresses deformation of the 1 st step surface 120d forming the capacitance C1 with the fixed electrode 16. As a result, the plurality of pressure sensors 110 can suppress variations in their sensing performance.

As described above, according to embodiment 2, as in embodiment 1, power consumption due to the capacitance between shield electrode 24 and diaphragm 20 can be suppressed without reducing the sensitivity.

(embodiment mode 3)

Embodiment 3 is a structure different from embodiment 1 described above, and the distance between the fixed electrode and the diaphragm is smaller than the distance between the shield electrode and the diaphragm. In the pressure sensor according to embodiment 3, substantially the same components as those of the pressure sensor 10 according to embodiment 1 are denoted by the same reference numerals. The pressure sensor according to embodiment 3 will be described focusing on differences from embodiment 1 described above.

Fig. 7 is a sectional view of a pressure sensor according to embodiment 3 of the present invention.

As shown in fig. 7, in the pressure sensor 210, a distance L1 between the fixed electrode 216 and the diaphragm 220 is smaller than a distance L2 between the shield electrode 24 and the diaphragm 220.

Specifically, in the case of embodiment 3, the surface 220c of the diaphragm 220 on the base substrate 12 side is not a multi-step structure but a single plane, unlike embodiment 1 described above. Instead, at least a central portion of the fixed electrode 216 has a thickness greater than a thickness of the shield electrode 24. As a result, the distance L1 between the fixed electrode 216 and the diaphragm 220 is smaller than the distance L2 between the shield electrode 24 and the diaphragm 220.

As described above, according to embodiment 3, as in embodiment 1, power consumption due to the capacitance between the shield electrode 24 and the diaphragm 220 can be suppressed without reducing the sensitivity.

The present invention has been described above by referring to embodiments 1 to 3, but the embodiments of the present invention are not limited thereto.

For example, in the case of embodiment 1 described above, as shown in fig. 3, the surface 20c of the diaphragm 20 on the base substrate 12 side has a two-step structure including the 1 st step surface 20d and the 2 nd step surface 20 e. However, the embodiments of the present invention are not limited thereto.

Fig. 8 is a sectional view of a pressure sensor according to another embodiment of the present invention.

As shown in fig. 8, in the pressure sensor 310 according to another embodiment, the surface 320c of the diaphragm 320 on the base substrate 12 side has a multi-step structure including a 1 st step surface 320d, a 2 nd step surface 320e, and a 3 rd step surface 320 g. When viewed from the opposing direction (Z-axis direction) of the fixed electrode 16 and the diaphragm 320, a 3 rd step surface 320g is provided between the 1 st step surface 320d and the 2 nd step surface 320e so as to surround the 1 st step surface 320 d. The 1 st step surface 320d faces the central portion of the fixed electrode 16, the 3 rd step surface 320g faces the outer peripheral portion of the fixed electrode 16, and the 2 nd step surface 320e is supported by the side wall portion 18. Among the 1 st to 3 rd step surfaces 320d, 320e, and 320g, the 1 st step surface 320d is closest to the base substrate 12, and the 2 nd step surface 320e is farthest from the base substrate 12.

In the other embodiment as well, as in embodiment 1 described above, power consumption due to the electrostatic capacitance between the shield electrode 24 and the diaphragm 320 can be suppressed without lowering the sensing sensitivity.

In the multi-step structure of the surface of the diaphragm on the base substrate side, in embodiment 1 described above, the 1 st step surface and the 2 nd step surface are connected by the wall surfaces substantially orthogonal to these. Alternatively, the two step surfaces may be connected by a slope-like inclined surface.

For example, in the case of embodiment 2 described above, as shown in fig. 6, the 1 st step surface 120d of the diaphragm 120 has a shape that narrows in the longitudinal direction (X-axis direction). However, the external force continuously acting on the pressure sensor to maintain the local portion of the diaphragm portion in the deformed state differs depending on the form of use of the pressure sensor.

Fig. 9 shows a surface of a base substrate side of a diaphragm of a pressure sensor according to a different embodiment of the present invention. Fig. 10 shows a surface of a base substrate side of a diaphragm of a pressure sensor according to another different embodiment of the present invention.

As shown in fig. 9, the 1 st step surface 420d of the diaphragm 420 of the pressure sensor of the different embodiment is narrowed in the width direction (Y-axis direction). This embodiment is employed when an external force that continuously deforms both end portions (cross-hatched portions) of the diaphragm portion 420b of the diaphragm 420 in the width direction continuously acts on the pressure sensor.

As shown in fig. 10, the 1 st step surface 520d of the diaphragm 520 of the pressure sensor according to the other embodiment is narrowed in both the longitudinal direction (X-axis direction) and the width direction (Y-axis direction). This embodiment is employed when an external force that continuously deforms both end portions in the longitudinal direction and both end portions in the width direction of the diaphragm portion 520b of the diaphragm 520 continuously acts on the pressure sensor.

In the case of embodiment 1 described above, the pressure sensor 10 can measure the pressure until the pressure at which the diaphragm 20 comes into contact with the fixed electrode 16 is reached. However, the embodiments of the present invention are not limited thereto.

For example, a dielectric layer may be provided on the surface of the fixed electrode facing the diaphragm. In this case, as the pressure applied to the diaphragm increases, the diaphragm approaches the dielectric layer and then comes into contact. After contact, as the pressure increases, the contact area of the diaphragm with respect to the dielectric layer increases. Until the contact, as the distance between the diaphragm and the fixed electrode decreases, the electrostatic capacitance between them increases, and after the contact, the electrostatic capacitance increases due to the increase in the contact area. Based on the change in the electrostatic capacitance in the two stages, the pressure acting on the diaphragm is measured (calculated). Such pressure sensors are referred to as touch mode pressure sensors.

That is, the pressure sensor according to the embodiment of the present invention broadly includes: a base substrate; a 1 st insulating layer provided on the base substrate; a fixed electrode provided on the 1 st insulating layer; a sidewall portion provided on the 1 st insulating layer and surrounding the fixed electrode; and a diaphragm having conductivity, facing the fixed electrode with a space therebetween, and supported by the side wall portion, wherein the side wall portion includes a shield electrode disposed on the 1 st insulating layer and a 2 nd insulating layer disposed on the shield electrode, and a distance between the fixed electrode and the diaphragm is smaller than a distance between the shield electrode and the diaphragm.

While the present invention has been described above by referring to a plurality of embodiments, it will be apparent to those skilled in the art that at least one embodiment can be combined with another embodiment in whole or in part as another embodiment of the present invention.

Industrial applicability

The present invention can be applied to an electrostatic capacitance type pressure sensor.

Description of the reference numerals

10. A pressure sensor; 12. a base substrate; 14. 1 st insulating layer; 16. a fixed electrode; 18. a sidewall portion; 20. a membrane; 24. a shield electrode; 26. a 2 nd insulating layer; l1, distance; l2, distance.