JPH1048083A - Manufacture of electrostatic capacity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such a manufacturing method of an electrostatic capacity sensor as being capable of improving the positioning precision of electrodes, providing stable sensor property and stabilizing electric insulation property of the electrodes. SOLUTION: This electrostatic capacity sensor has a hole 15 made in the second substrate layer 13 of a chip 10 ranging from the outer surface 13b to a silicon oxide film layer 11. In the oxide film layer 11, a space 16 where the inside surface 12a of the first silicon substrate layer 12 is opposed to the inside surface 13a of the second silicon substrate layer 13 is formed by removing the necessary end of the hole 15. Fluid application diffusing agent is supplied into the space 16 to be poured therein in a depressurized atmosphere. The application diffusing agent applied to the inner periphery of the space 16 is heated for diffusion to form the first electrode layer 17 and the second electrode layer 18 so that a spatial displacement between the first electrode layer 17 and the second electrode layer 18 to be measured can be detected by the change of an electrostatic capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a capacitance type semiconductor sensor (such as a pressure sensor or an acceleration sensor).
In particular, the present invention relates to a method for manufacturing a capacitance-type sensor suitable for improving the positional accuracy of electrodes and reducing variations in characteristics.

[0002]

2. Description of the Related Art An ordinary capacitance type semiconductor pressure sensor is
For example, it has a chip structure as shown in FIG. This sensor chip is, as shown in the figure, a silicon Si substrate a
The thin film portion a1 is formed by an etching process, and the thin film portion b1 is formed also on the glass substrate b by an etching process. Then, an electrode c1 made of, for example, a p ⁺ layer is formed on the thin film portion a1, and an electrode c2 made of, for example, platinum is formed on the thin film portion b1. The silicon Si
A glass substrate b is bonded to a substrate a with electrodes c1 and c2 facing each other, and a gap is formed between each of the electrodes c1 and c2 to form a capacitor. The prior art relating to the capacitance type semiconductor pressure sensor includes, for example, JP-A-2-134570 and JP-A-8-128909.

In the capacitance type semiconductor pressure sensor shown in FIG.
When the pressure changes, the thin film portion a1 of the silicon substrate a is distorted, and the electrode c2 on the lower surface of the facing glass b and the silicon S
i and the distance change between the electrodes c1 on the substrate a, whereby the capacitance C ₀ is also changed. Then, the capacitance C ₀
Is converted into a frequency so that a pressure change can be extracted as a signal. Electrodes c1, c2
The distance between them is about several μm.

[0004]

However, according to the above structure, the electrodes c1 and c2 must be formed on the silicon Si substrate a and the glass substrate b and then bonded in the next step. , C1 are likely to be displaced in the plane direction. In addition, since the glass substrate b is etched, variations in etching in the depth direction at that time appear, and controllability of positional accuracy in the distance direction between the electrodes is poor. Therefore, in the conventional capacitance type semiconductor sensor,
Variations occur in characteristics (electrical insulation characteristics) due to variations in positional accuracy.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and is intended to manufacture a capacitance type sensor capable of improving the positional accuracy of electrodes and obtaining sensor characteristics with stable electrical insulation characteristics. It is an object to provide a method.

[0006]

The present invention has the following arrangement to solve the above-mentioned problems. According to the first aspect of the present invention, a hole extending from the outer surface to the position of the intermediate layer is formed in the second substrate layer of the laminated material having the first substrate layer and the second substrate layer on both surfaces of the intermediate layer by etching. And a space forming step of forming a space where the inner surface of the first substrate layer and the inner surface of the second substrate layer face each other by removing a required portion of the intermediate layer by etching. A step of supplying a flowable application / diffusion agent to the space and pouring the application / diffusion agent into the space under a reduced pressure atmosphere, and heating the laminated material to which the application / diffusion agent adheres to the inner peripheral surface of the space. By performing the diffusion process of the diffusion source, the first in the space portion
Forming the first electrode layer on the inner surface of the substrate layer
An electrode layer forming step of forming a second electrode layer on the inner surface of the substrate layer, and detecting a displacement of a distance between the first electrode layer and the second electrode layer due to a measurement object by a change in capacitance. A method for manufacturing a capacitance-type sensor, characterized in that:

According to the first aspect of the present invention, a first substrate layer and a second substrate layer are provided on both surfaces of the intermediate layer. This may be in the state of a wafer material. A hole is formed in the second substrate layer from the outer surface to the position of the intermediate layer, and a necessary portion of the hole in the intermediate layer is removed to form a space. In this space, the inner surface of the first substrate layer and the inner surface of the second substrate layer face each other, and an electrode layer is formed on each of the inner surfaces.

[0008] The accuracy of the interval between the electrode layers depends only on the thickness of the intermediate layer.
The accuracy of the distance between the electrodes does not decrease due to the decrease in the etching accuracy as in the related art. Further, since the inner surface of the first substrate layer and the inner surface of the second substrate layer are also spread with respect to the expansion of the space, and opposed at the same position despite the expansion of the removed portion, no positional displacement occurs. . Therefore, the accuracy of the distance between the electrodes and the position of the opposing electrodes is increased, and a stable sensor with less variation in characteristics can be obtained.

In the case where an SOI wafer having a silicon oxide film (SiO ₂ ) layer as an intermediate layer and a silicon substrate as the first and second substrate layers is used as a laminated material, the thickness of the silicon oxide film layer is reduced. Uniform and accurate control is easy, and when the film thickness is several μm, the film thickness accuracy can be ± 100 °, so that the accuracy of the electrode interval is extremely good.

The electrode is formed by using a flowable coating and diffusing agent, supplying it to the space, pouring it into the space under a reduced pressure atmosphere, and volatilizing the solvent of the coating and diffusing agent. After that, the diffusing agent applied to the inner peripheral surface of the space is heated to perform a diffusion process. Here, there is gas diffusion in the diffusion, but when the intermediate layer is a silicon oxide film, the layer thickness is several μm as described above, and the space becomes a gap of the layer thickness. In addition, it is difficult for gas to enter the inside of the above-mentioned gap particularly, and it is difficult to uniformly diffuse gas in the entire space. On the other hand, bubbles are likely to remain in the interior of the space simply by supplying the fluid application / diffusion agent to the interior of the space. Run away from the agent. For this reason, it is possible to remove bubbles in the application and diffusion agent in the space. Therefore, the diffusing agent can be uniformly applied to the inner peripheral surface of the space that is the electrode forming portion.

In the meantime, an electrode is formed in the space by a diffusion process. At this time, the electrode is also diffused into the silicon oxide film layer. However, since this may cause electrical conductivity, the silicon oxide film layer is diffused. Removed by etching,
Ensure the electrical insulation properties of the sensor.

In addition to the intermediate layer being a silicon oxide film layer of SOI, a third silicon substrate layer is epitaxially grown on the first silicon substrate layer to form an intermediate layer, and the intermediate layer is formed on the third silicon substrate layer. The second silicon substrate layer can be further epitaxially grown into a silicon wafer material.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 4 are explanatory views of a structure and a manufacturing process of a capacitance type semiconductor pressure sensor chip according to an embodiment of the present invention, FIG. 5 is an explanatory view of a case where the pressure sensor is incorporated in a package, and FIG. FIG. 3 is an explanatory diagram provided on a chip upper surface.

As shown in FIG. 2C, the manufactured chip 10 has a first silicon substrate layer 12 and a second silicon substrate layer 12 on both surfaces of a silicon oxide (SiO ₂ ) film layer 11 as an intermediate layer.
A sensor chip 10 having a silicon substrate layer 13 having a pyramid shape formed in the second silicon substrate layer 13 from the lower surface (outer surface) to the lower position of the silicon oxide film layer 11. Have been.

In the silicon oxide film layer 11, a required portion (a portion around the tip) 15 a of the tip of the hole 15 is removed, and the inner surface 12 a of the first silicon substrate layer 12 and the inner surface 12 a of the second silicon substrate layer 13 are removed. A space portion 16 whose front surface 13a faces is formed. The space 16 has a disk shape, and the space is connected between the hole 15 and the space 16, and the space has a substantially mushroom shape.

The inner surface 1 of the first silicon substrate layer 12
2a, the first electrode layer 17 is formed, and the hole 1 is formed from the outer surface 13a of the second silicon substrate layer 13.
5 and the inner surface 13a of the second silicon layer.
The second electrode layer 18 is formed on the first electrode layer 1.
7 and the second electrode layer 18 has a structure of a capacitor having a capacitance C ₁ at the location of the face. Each of the first electrode layer 17 and the second electrode layer 18 is formed by a diffusion layer (for example, boron B is diffused).

In the chip 10, a terminal 21 comprising an aluminum pad 19 and a high-concentration diffusion layer 20 is formed and connected to the first electrode layer 17. In such a capacitance type sensor, the first silicon substrate layer 12 on the space 16 is displaced by guiding the pressure to be detected onto the first silicon substrate layer 12, and the first pressure is displaced by the displacement. and interval displacement between the electrode layer 17 and the second electrode layer 18, which capacitance C ₁ by the displacement detected by converting the frequency to change, and to detect the detection target pressure from the frequency It is.

In the chip 10, a silicon oxide film (SiO ₂ film) 2 is formed as a protective film on the upper surface of the first silicon substrate.
2. Further, a silicon nitride film (SiN film) 23 is formed on the upper surface.

Next, a method of manufacturing the above-mentioned capacitance type pressure sensor will be described with reference to FIGS. As shown in FIG. 1A, first, a wafer material 14 having a first silicon substrate layer 12 and a second silicon substrate layer 13 on both upper and lower surfaces of a silicon oxide film layer 11 is prepared. This wafer material 14 may be manufactured or purchased.
In addition, a large number of chips 10 are simultaneously manufactured from the above-described wafer material 14.

Next, as shown in FIG. 1 (b), silicon oxide (SiO ₂ ) films 22 and 24 and silicon nitride (SiN) films 23 and 24 are formed on both upper and lower surfaces of the wafer material 14 as protective films. 25 is formed.

Next, as shown in FIG.
A hole 15 having a conical shape extending from the outer surface of the lower surface to the position of the silicon oxide film layer 11 is formed in the silicon substrate layer 13 by etching (a hole etching step). in this case,
A resist is applied by photolithography, and the resist is removed in a state where the pattern of the hole 15 is opened.
4 is removed by etching. Thereafter, the resist is removed, and the second silicon substrate layer 13 is removed by anisotropic etching with an etching solution such as KOH according to the pattern, thereby forming a hole 15. This etching stops in contact with the silicon oxide film layer 11 as the intermediate layer, and the hole 1
5 is vacant, for example, in the shape of a flat pyramid on the top surface.

Next, as shown in FIG. 1D, the silicon oxide film layer 11 is etched with a hydrofluoric acid (hydrofluoric acid) based etching solution. This etching is an isotropic etching, and a necessary portion (a portion around the tip) 15a of the tip of the hole 15 is removed by etching, and the inner surface 12a of the first silicon substrate layer 12 and the second silicon substrate layer 13 are removed.
The space 16 where the inner surface 13a faces is formed (space forming step). The hole 15 and the space 16 have a mushroom shape. Then, the silicon oxide film 24 and the nitride film 25
And are removed by etching.

Next, as shown in FIG. 3A, a flowable coating / diffusing agent 16a is flowed over the wafer material 14 to remove the holes 15 from the outer surface 13b of the second silicon substrate layer 13.
It is supplied to the inner peripheral surface portion and further into the space portion 16. Then, as shown in FIG. 3B, the solvent is vaporized to apply only the diffusing agent of the coating and diffusing agent to the lower surface of the second silicon substrate layer 13 on the inner peripheral surface of the space 16 and the inner peripheral surface of the hole 15. .

That is, the coating and diffusing agent 16a contains a diffusing agent that diffuses to the substrate by heat treatment.
It is preferable to use a coating and diffusing agent having fluidity consisting of a diffusing agent + an organic binder + an alcohol-based solvent,
Further, it is preferable to use PBF (polyboron film: product name of Tokyo Ohka Kogyo Co., Ltd.). Further, the wafer material 14 into which the coating diffuser 16a has been poured is shown in FIG.
As shown in (a), bubbles B remain under normal pressure. Then, when the wafer material 14 is placed in a vacuum chamber and decompressed, as shown in FIG. 4 (b), the bubbles B emerge and escape from the surface of the application / diffusion agent 16 a, whereby Completely remove the remaining air bubbles.

After the bubbles are removed, the coating and diffusion agent 16
The solvent of a is volatilized, and only the diffusion agent of the application diffusion agent 16a is applied to the inner peripheral surface of the space 16, the inner peripheral surface of the hole 15, and the lower surface of the second silicon substrate layer 13. By subjecting this to heat treatment, the inner peripheral surface of the hole 15 including the inner peripheral surface of the space 16,
To the lower surface of the silicon substrate layer 13.

As described above, as shown in FIG.
Along with the formation of the first electrode layer 17 on the inner surface 13a of the first silicon substrate layer 13, the second silicon substrate layer 1
Then, a second electrode layer 18 is formed from the outer surface 13b of the third electrode 3 to the inner peripheral surface 15a of the hole 15 and the inner surface 13a of the second silicon substrate layer 13 (electrode forming step). In this step, the portion 11a of the silicon oxide film layer 11 facing the space 16 is
Also diffuses simultaneously (SiO ₂ + B).

Next, as shown in FIG. 2B, the portion 1 where the silicon oxide film layer 11
1a is removed by etching (removal step). The removal of the portion 11a is performed because the portion 11a becomes conductive by diffusion and affects the electrical insulation characteristics of the sensor.
This is done to eliminate the effect. However, if the diffusion is only to such an extent that the electrical insulation characteristics of the sensor are not affected, this removing step can be omitted.

Next, as shown in FIG.
From the upper surface of the silicon substrate layer 12 toward the first electrode layer 17, an electrode hole 26 is formed in the nitride film 23 and the silicon oxide film 22.
And the portion of the first silicon substrate layer 12 between the electrode hole 26 and the first electrode layer 16 is
0 is formed to provide conductivity. Then, the aluminum pad 19 is formed so as to be fitted into the electrode hole 26. In addition, from the lower surface of the chip 10, the second electrode layer 1
8 is exposed.

The chips 10 formed on the wafer material 14 as described above are individually separated from the wafer material 14 by dicing. As shown in FIG. 5, the divided chip 10 is housed in a package 27 with its upper part opened in a bowl shape. A pair of pin terminals 28a and 28b are fixed to the package 27, and the second electrode layer 18 exposed on the bottom surface of the accommodated chip 10 is mounted on one of the pin terminals 28a and connected to the aluminum pad. Lead 29 from the top of 19
To another pin terminal 28b. Then, an introduction pipe or the like is provided in an empty portion of the package 27 so that pressure can be introduced from above.

In the sensor, the pin terminals 28a, 28
A frequency signal is input to the two electrode layers 17 and 18 via 8b to detect a change in capacitance due to a displacement (change) in the interval between the two electrode layers 17 and 18. Details of the detection of the capacitance are omitted because they are well known.

According to the pressure sensor of the embodiment, the accuracy of the interval between the electrode layers 17 and 18 depends only on the thickness of the silicon oxide film layer 11 which is the intermediate layer. As long as the thickness accuracy is improved, the accuracy of the distance between the electrodes 17 and 18 does not decrease due to the decrease in etching accuracy as in the related art. In addition, since the inner surface 12a of the first silicon substrate layer 12 and the inner surface 13a of the second silicon substrate layer 13 also spread with respect to the expansion of the space 16 and oppose at the same position regardless of the expansion of the removed portion, No displacement occurs between the electrode layers 17 and 18.
Therefore, the accuracy of the distance between the electrodes and the position of the opposing electrodes is increased, and a stable sensor with less variation in characteristics can be obtained.

In forming the electrode layers 17 and 18 by the diffusion process, the diffusion process is performed not by the diffusion process in the gas atmosphere but by the flow of the fluid coating and diffusion agent 16a and the heating after the pressure is reduced. . In the diffusion, there is a gas diffusion treatment in a gas atmosphere. However, since the inside of the space 16 is extremely narrow (can be made to be about several μm), in the gas diffusion, the gas hardly enters the inside of the above-mentioned gap particularly in the space. It is difficult to perform uniform diffusion over the entirety. When the fluid application / diffusion agent 16a is merely supplied to the space 16, air bubbles tend to remain in the interior of the space 16; It evaporates from the agent 16a to the outside. Therefore, the fluid diffusing agent can be easily poured into the narrow space 16 and the space 16 serving as an electrode forming portion can be easily formed.
Can be uniformly applied to the inner peripheral surface of the substrate. Next, the solvent of the applied diffusing agent 16a is removed and inserted into a diffusion furnace to perform diffusion processing, whereby uniform electrode layers 17, 18 can be formed.

The chip 10 is an SOI wafer having a silicon oxide film (SiO ₂ ) layer as an intermediate layer. The silicon oxide film layer 11 has a uniform thickness and is easily controlled accurately. Film thickness accuracy of ± 100 mm at several μm
Therefore, the width accuracy of the space, that is, the control accuracy of the electrode interval is extremely good. Therefore, a very small pressure change can be detected, for example, 50 g / cm ² can be detected. Also, since the space in the vertical direction of the space 16 is narrow,
Even if the first silicon substrate 12 is greatly deformed due to an excessive force, the inner surface 12a of the first silicon substrate 12 abuts against the inner surface of the second silicon substrate 13 and serves as a stopper. Even if it becomes, the destruction of the sensor chip 10 in the manufacturing process can be prevented.

In the step of diffusing the space, the electrodes 17 and 18 are formed.
Is formed, and at this time, the silicon oxide film layer 11 is also diffused. However, since this may cause electrical conductivity, a portion where the silicon oxide film layer has been subjected to the diffusion treatment is removed by etching, and the sensor electric current is removed. To ensure proper insulation properties. However,
If unnecessary, the step can be omitted.

Here, a chip 30 according to a modification of the embodiment will be described.
Is shown in FIG. That is, in the chip 10 shown in FIGS. 1 to 3, electrical connections are formed from the electrode layers 17 and 18 above and below the chip 10, and the aluminum pad 19 and the second
Electrode layer 1 extending to the lower surface of silicon substrate layer 13 of FIG.
8) The electrical connection to the chip is made from above and below the chip. In the chip 30 of this modified example, the same portion 30A as the above-mentioned chip 10 (the same reference numerals are given to the same portions as the chip 10). And a conductive portion 30 </ b> B for electrically connecting the second electrode layer 18 to the upper surface of the chip 30.

In the conductive portion 30B, a hole 31 is formed in the silicon oxide film layer 22 and the nitride film 23 on the upper surface of the chip 30, and a portion 32 of the first silicon substrate layer 12 corresponding to a lower portion of the hole 31 is diffused by high concentration. Have conductivity. Also, the second
In the silicon substrate layer 13, a pyramid-shaped hole 33 is formed by etching (simultaneously with the formation of the above-described hole 15), and the silicon 34 in a portion (corresponding to a required tip) 34 located at the tip of the hole 33 is formed. The oxide film layer 11 is removed by etching. Then, the second electrode layer 1 is formed on the inner peripheral surface of the hole 33.
The electrode layer 35 electrically connected to 8 is formed at the same time.

By flowing aluminum into the upper hole 31 and the lower hole 33 and the portion 34, the second electrode layer 18 is separated from the upper aluminum 36b via the lower aluminum 36a and the high concentration diffusion portion 32. Connect to pad 37 on top.

In the chip 30, the aluminum pad 19 and the pad 37 are both formed on the upper surface of the chip 30, and the two terminals are installed in the same direction. The connection to is very easy.

Next, another embodiment of the present invention will be described with reference to FIG. In other embodiments, the present invention is applied to an acceleration sensor. FIGS. 7A and 7B are a vertical sectional view and a plan view showing a chip 40 of the capacitive acceleration sensor. 1 to 3 are denoted by the same reference numerals.

As shown in the drawing, the acceleration sensor chip 40 includes the pressure sensor chip 1 shown in FIGS.
Further, a groove 41 is formed in the nitride film 23, the silicon oxide film 22, and the first silicon substrate layer 12 from the upper surface toward the vicinity of the edge of the space 16, and a thin wall is formed between the groove 41 and the space 16. A part 42 is formed, and a part of the first silicon substrate layer 12 surrounded by the groove 41 is used as a mass part 43. In this embodiment, as shown in FIG. 7B, the grooves 41 are formed in a continuous circular shape when viewed from above, and
A columnar mass 43 is formed. Of course, the groove 41 may have a shape other than a circle.

In this acceleration sensor, when an acceleration is applied, the mass portion 43 becomes a weight body and the thin portion 42 becomes a beam and bends, whereby the first electrode layer 17 and the twenty-first electrode layer 1 are bent.
8, the acceleration can be detected from the change in capacitance as in the case of the pressure sensor.

In still another embodiment, the intermediate layer may be formed by epitaxial growth instead of the silicon oxide film of the above embodiment. In this case, for example, the first silicon substrate layer is formed of a p-type silicon semiconductor layer,
An n-type silicon semiconductor layer is formed as an intermediate layer on the upper surface by epitaxial growth, and a second
Using an epitaxial wafer material obtained by epitaxially growing a silicon substrate layer and a p-type silicon semiconductor layer, a sensor can be manufactured by etching and forming diffusion electrodes. Of course, an epitaxial wafer material made of another semiconductor material may be used.

[0043]

As described above, according to the present invention, the accuracy of the interval between the electrode layers depends only on the thickness of the intermediate layer.
As long as the thickness accuracy of the intermediate layer is improved, the accuracy of the distance between the electrodes does not decrease due to the decrease in the etching accuracy as in the related art. In addition, the inner surface of the first substrate layer and the inner surface of the second substrate layer also expand with respect to the expansion of the space,
Because they face at the same position regardless of the extent of the removed part,
No displacement occurs.

Accordingly, the distance between the electrodes and the accuracy of the opposing positioning are increased, and stable sensor characteristics with little variation can be obtained. When the present invention is applied to a pressure sensor, it is necessary to reduce the thickness of the diaphragm in order to increase the accuracy. Conventionally, the diaphragm may be damaged in the process. However, in the present invention, the thickness of the space can be reduced, and the inner surface of the second substrate layer functions as a stopper, so that the number of diaphragm cracks in the process is reduced and the yield is improved.

Further, bubbles are likely to remain in the interior of the space simply by supplying the fluid application / diffusion agent to the interior of the space. Volatilizes from the agent to the outside. Therefore, the fluid diffusing agent can be easily poured even in a narrow space, and the diffusing agent can be uniformly applied to the inner peripheral surface of the space as the electrode forming portion. Therefore, a uniform electrode layer can be formed by the diffusion treatment, the variation in the electrical insulation characteristics of the sensor is eliminated, and the yield is greatly improved.

[Brief description of the drawings]

FIGS. 1A to 1D are explanatory views of the structure and manufacturing process of a capacitance type semiconductor pressure sensor chip according to an embodiment of the present invention.

FIGS. 2 (a) to 2 (c) are explanatory views of the structure and the manufacturing process of the sensor chip following FIG.

FIG. 3 (a) is an explanatory view of an application state of an application and diffusion agent, and FIG.
FIG. 3 is an explanatory diagram of a diffusion source attached state in which a solvent is removed.

FIG. 4 (a) is an explanatory view of a coating state of a coating diffuser, and FIG. 4 (b).
FIG. 3 is an explanatory diagram of a state of defoaming.

FIG. 5 is an explanatory view of a case where a capacitance type sensor is incorporated in a package.

FIG. 6 is an explanatory diagram in which sensor wiring is provided on the upper surface of a chip.

FIGS. 7A and 7B are explanatory views of an embodiment in which the present invention is applied to an acceleration sensor, and FIGS. 7A and 7B are a longitudinal sectional view and a plan view showing a chip of the capacitive acceleration sensor. FIGS.

FIG. 8 is an explanatory view of a vertical sectional structure of a conventional capacitance type semiconductor pressure sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pressure sensor chip 11 Silicon oxide film layer 12 1st silicon substrate layer 13 2nd silicon substrate layer 14 Wafer material 15 Hole 15a Necessary tip 16 Space 16a Coating and diffusion agent 17 First electrode layer 18 Second electrode Layer 30 Pressure sensor chip 30A Sensor unit 30B Conductive unit 40 Acceleration sensor chip

Claims (1)

[Claims] 1. A hole for etching a hole extending from an outer surface to a position of an intermediate layer in a second substrate layer of a laminated material having a first substrate layer and a second substrate layer on both surfaces of the intermediate layer. A processing etching step, and a space forming step of forming a space where the first substrate layer inner surface and the second substrate layer inner surface face each other by removing a required portion at the tip of the hole of the intermediate layer by etching, A step of supplying a flowable application / diffusion agent to the space and pouring the application / diffusion agent into the space under a reduced-pressure atmosphere; and heating a laminated material to which the application / diffusion agent adheres to the inner peripheral surface of the space to obtain a diffusion source. Forming a first electrode layer on the inner surface of the first substrate layer in the space and forming a second electrode layer on the inner surface of the second substrate layer by performing the diffusion process A first electrode layer and a second electrode layer depending on the object to be measured. Method of manufacturing a capacitive sensor, characterized in that the displacement of the distance between the electrode layers to detect a change in capacitance.