JP2003279522A - Gaseous hydrogen detecting apparatus and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gaseous hydrogen detecting apparatus capable of highly accurately, speedily, and easily detecting leakage of a hydrogen gas even in an inert gas atmosphere or in an oxygen-free environment such as in a vacuum, and to provide its manufacturing method. <P>SOLUTION: The gaseous hydrogen detecting apparatus detects concentration of the gaseous hydrogen in both an oxygen-free environment and an oxygen- present environment, and is provided with an insulating substrate 310, sensing membranes 30 and 31 having Pd as a main component and provided on one surface of the insulating substrate, and oxidation-resistive membranes 90 and 91 having a metal element as a main component hardly oxidizable in the atmosphere and provided on the sensing membranes. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a hydrogen gas concentration in an oxygen-free environment in an inert gas atmosphere or in a vacuum such as outer space, and detects hydrogen gas in an atmosphere containing oxygen. The present invention relates to a device and a manufacturing method thereof.

[0002]

2. Description of the Related Art A conventional hydrogen gas sensor is a catalytic combustion type,
Semiconductor type and solid electrolyte type sensors are used,
None of them operate in an oxygen-free environment such as in an inert gas atmosphere or in a vacuum, and operate only in the coexistence with a gas containing oxygen such as air. Hydrogen that may be generated in a container that stores compressed hydrogen gas or a container that stores liquefied hydrogen that is installed in an explosion-proof atmosphere filled with an inert gas such as nitrogen or helium using a conventional hydrogen gas sensor The conventional method employed to detect gas leakage is shown in FIGS.

FIG. 11 is a schematic diagram showing a leakage detection method in a compressed hydrogen storage container installed in an explosion-proof atmosphere. In this figure, reference numeral 110 is a compressed hydrogen storage container,
Reference numeral 120 is a container filled with an inert gas, reference numeral 130 is a sampling pipe, reference numeral 131 is an air introduction pipe, reference numeral 140 is a suction pump, reference numerals 150 and 151 are flow rate adjusting valves, reference numeral 152 is a mixer,
Reference numeral 160 is a conventional hydrogen gas sensor. In this conventional leak detection method, a part of the atmosphere in the container 120 filled with the inert gas is sucked and guided by the suction pump 140 to the mixer 152 via the sampling pipe 130 and the flow rate adjusting valve 150. At the same time, oxygen-containing air is sucked and guided by the suction pump 140 to the mixer 152 via the air introducing pipe 131 and the flow rate adjusting valve 151. A structure is adopted in which, after the sampling gas and air are sufficiently mixed in the mixer 152, they are introduced into the conventional hydrogen gas sensor 160 and hydrogen leakage is detected.

[0004]

However, the above-mentioned conventional hydrogen gas leakage detection method has the following problems (1) to (3).

(1) Since the gas is sucked by the pump through the sampling pipe, it takes a long time to detect a gas leak.

(2) If there are many places where leakage detection is desired, many suction pipes and suction pumps must be installed, and the number of points that can be detected is limited.

(3) In outer space, on the moon, on other planets,
In an environment where there is no atmosphere containing oxygen, oxygen gas must also be supplied separately.

FIG. 12 shows another conventional example. FIG. 12 is a schematic diagram showing a leakage detection method in a liquefied hydrogen storage container installed in an explosion-proof atmosphere. In this figure, reference numeral 111 is a liquefied hydrogen storage container, reference numeral 120 is a container filled with an inert gas, reference numeral 121 is a heat insulating material, and other same numbers are the same as in FIG.
Is the same as This leak detection method is substantially the same as the leak detection method shown in FIG.
There is (3).

FIG. 13 shows another conventional example. FIG. 13 is a schematic diagram showing a liquefied hydrogen storage container installed in a vacuum heat insulating container. In this figure, reference numeral 111 indicates a liquid hydrogen storage container, and reference numeral 122 indicates a vacuum heat insulating container. In this example, since the place where there is a risk of leakage is a vacuum and the atmosphere cannot be sampled, the leakage detection method using the conventional hydrogen gas sensor shown in FIGS. 11 and 12 is applied. The leak that occurs in the liquefied hydrogen storage container cannot be prevented, and there is no other way than detecting the pressure rise in the vacuum insulation container with the pressure gauge 161, and whether hydrogen is leaking or the atmosphere is leaking into the vacuum insulation container. There is a problem that can not be determined.

Further, since the upper limit of the detection sensitivity of the conventional hydrogen gas sensor is about 1000 ppm, when it is necessary to detect even hydrogen with a higher concentration, a sufficient sampling gas should be introduced before introducing the sensor. There is also the problem of having to dilute.

FIG. 14 shows another conventional example. 14
FIG. 3 is a cross-sectional structural view of a hydrogen gas sensor capable of detecting hydrogen gas in an inert gas or in an oxygen-free environment such as vacuum. In this figure, reference numeral 310 is an insulating substrate such as glass, reference numeral 330 is a thin film containing Pd as a main component, and reference numerals 340a and 340a.
40b is an electrode film containing a metal such as Al, Ni, Au, Ag, Ti, and Cr as a main component. The sensor shown in this example is
When exposed to hydrogen, hydrogen diffuses into the thin film 330 containing Pd as a main component and enters the inside of the crystal lattice, which makes it difficult for electrons to flow. Therefore, it is measured as an increase in electrical resistance between the metal electrode films 340a and 340b. 11 to 13 described above.
Unlike the conventional example, it is possible to detect hydrogen gas even in an oxygen-free atmosphere.

However, in this conventional method, hydrogen is easily oxidized (combusted) on the surface of the thin film 330 due to the catalytic effect peculiar to the Pd element in an atmosphere in which even a slight amount of oxygen exists, so that the thin film There is a problem that hydrogen cannot enter the inside of 330, the electric resistance between the metal electrode films 340a and 340b does not change, and the presence of hydrogen cannot be detected.

The present invention has been made to solve the above-mentioned problems, and it is possible to leak hydrogen gas with high accuracy, speed and easily even in an oxygen-free environment such as an inert gas atmosphere or a vacuum. An object of the present invention is to provide a hydrogen gas detection device that can detect hydrogen gas and a method for manufacturing the same.

[0014]

A hydrogen gas detecting device according to the present invention is a hydrogen gas detecting device for detecting the concentration of hydrogen gas in both an oxygen-free environment and an aerobic environment, which is an insulating substrate. And a sensing thin film containing Pd as a main component, which is provided on one surface of the insulating substrate, and an oxidation resistance containing a metal element that is difficult to be oxidized in the atmosphere and is provided on the sensing thin film. And a thin film.

A hydrogen gas detecting device according to the present invention is a hydrogen gas detecting device for detecting the concentration of hydrogen gas in both an oxygen-free environment and an aerobic environment. First provided on the side surface
And a second insulating film, a first sensing thin film containing Pd as a main component provided on the first insulating film, and oxidized in the atmosphere provided on the first sensing thin film. A first detection unit having a first oxidation resistance thin film containing a difficult metal as a main component; the first detection unit measuring the electric resistance of the first detection thin film; and the second insulation film. On top of P
A second sensing thin film containing d as a main component, a second oxidation resistance thin film provided on the second sensing thin film and containing a metal that is not easily oxidized in the atmosphere as a main component, and the other of the semiconductor substrates. A second sensing portion having a back surface electrode made of a conductor that is ohmic-connected on the side surface, and the second sensing portion applies a voltage between the back surface electrode and the second sensing thin film;
Measuring the capacitance of the second sensing thin film.

The oxidation resistant film is made of either Pt or Au and contains 99 of these noble metal elements.
It is desirable to contain at least 1 atomic% and it is permissible to contain up to 1 atomic% of Ag, Cu, etc. as unavoidable impurities. Although it is desirable to use either Pt or Au alone, it is also possible to add a small amount (maximum 5 atom%) of Ag, Si, Rd or the like to these and alloy them.

The above sensing thin film contains 9% Pd as a main component.
It contains 9.9 atomic% and the balance consists of unavoidable impurities (mainly gas component elements such as oxygen). Further, as an intentional additive, one kind or two or more kinds selected from the group of Cr, Ni and Ag of 50 atomic% or less may be added. Addition of these has the effect of expanding the hydrogen concentration measurement range. In addition, in the sensing thin film, A
It is possible to allow up to 0.5 atom% of l, Si and the like.

Further, in the device of the present invention, a conductive heat generating film provided on the other surface of the insulating substrate, an electrode film conducting to the heat generating film, and the heat generating film via the electrode film. It is preferable to provide a means for supplying power to. The heating film causes resistance heating by power supply, and the heating film that has generated heat heats the sensing thin film to a predetermined temperature via the insulating substrate. This increases the response speed of the sensing thin film to hydrogen and enables rapid detection.

Further, the device of the present invention includes a conductive heating film provided between the insulating substrate and the sensing thin film, and is inserted between the heating film and the sensing thin film to remove the heating film from the sensing thin film. It is preferable to include an insulating film that insulates, an electrode film that conducts to the heat generating film, and a means for supplying power to the heat generating film via the electrode film. The heating film causes resistance heating by power supply, and the sensing film is heated by the heated heating film through the insulating film.
Since the heat generating film is brought close to the sensing thin film and the sensing thin film is heated without the interposition of the insulating substrate, more rapid measurement becomes possible.

Further, a sensing portion is formed which includes an electrode film which is in contact with the sensing thin film and is conductive, and a measuring circuit which is connected to the electrode film. The detection unit detects the electric resistance of the sensing thin film.

The method for manufacturing a hydrogen gas detecting device according to the present invention is the method for manufacturing a hydrogen gas detecting device for detecting the concentration of hydrogen gas in an oxygen-free environment, wherein: (a) a first detecting portion is formed on the first detecting portion. Forming a first insulating film on the surface of the silicon substrate, and (b) removing the first insulating film in the depth direction by pattern etching, and then forming a second insulating film. A shallow hole in which the second detector is to be formed is formed, and the first insulating film is entirely removed in the depth direction to expose a part of the surface of the silicon substrate to form a third detector. Forming a deep hole to be formed, (c) forming a third insulating film by exposing the exposed surface of the silicon substrate in the deep hole to ozone, and (d) forming the third insulating film. P on the insulation film of 1
A first sensing thin film containing d as a main component is formed via an adhesion layer containing Cr or Ti as a main component, and a second sensing thin film containing Pd as a main component is formed on the second insulating film. Forming, and forming a third sensing thin film containing Pd as a main component on the third insulating film, and (e) the first sensing thin film.
A first oxidation resistant thin film containing a metal element that is difficult to be oxidized in the atmosphere as a main component on the sensing thin film, and a metal element that is hard to be oxidized in the atmosphere as a main component on the second sensing thin film. And forming a second oxidation resistance thin film
Forming on the third sensing thin film a third oxidation resistant thin film containing a metal element which is difficult to be oxidized in the atmosphere as a main component, and (f) ohmic connection on the first oxidation resistant thin film. Forming a first electrode made of a conductive conductor, forming a second electrode made of an ohmic-connected conductor on the second oxidation resistance thin film, and forming a second electrode on the third oxidation resistance thin film. And (g) forming a back electrode made of an ohmic-connected conductor on the back surface of the silicon substrate.

The method of manufacturing a hydrogen gas detecting device according to the present invention is the method of manufacturing a hydrogen gas detecting device for detecting the concentration of hydrogen gas in an oxygen-free environment, wherein (A) the first detecting portion is formed on the first detecting portion. A step of forming a first insulating film on the surface of the silicon substrate, and (B) pattern etching to completely remove the first insulating film in the depth direction, and then form a second insulating film. A shallow hole in which the second detector is to be formed is formed, and the first insulating film is entirely removed in the depth direction to expose a part of the surface of the silicon substrate to form a third detector. A step of forming a deep hole to be formed, and (C) exposing the exposed surface of the silicon substrate in the deep hole to oxygen plasma for oxidation
And (D) forming a first sensing thin film containing Pd as a main component on the first insulating film by Cr or Ti.
And a second sensing thin film containing Pd as a main component is formed on the second insulating film, and Pd is formed on the third insulating film. Forming a third sensing thin film containing a main component, and (E) forming a first oxidation resistance thin film containing a metal element which is difficult to oxidize in the atmosphere as a main component on the first sensing thin film. Forming a second oxidation resistant thin film containing a metal element which is not easily oxidized in the atmosphere as a main component on the second sensing thin film, and a metal which is not easily oxidized in the atmosphere on the third sensing thin film. A step of forming a third oxidation resistant thin film containing an element as a main component, and (F) forming a first electrode made of an ohmic-connected conductor on the first oxidation resistant thin film, and It consists of a conductor that is ohmic connected on the oxidation resistance thin film of 2. To form a second electrode,
Forming a third electrode made of an ohmic-connected conductor on the third oxidation resistance thin film; and (G) forming a back electrode made of an ohmic-connected conductor on the back surface of the silicon substrate. And a process.

[0023]

Various preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) A hydrogen gas detection apparatus according to the first embodiment will be described with reference to FIG.

In this embodiment, the glass substrate 310 is used as the insulating substrate. A sensing thin film 30 containing Pd as a main component is laminated on the surface side of the glass substrate 310, and an oxidation resistance thin film 90 is further laminated on the sensing thin film 30.
A pair of electrode films 40a, 40 are provided at appropriate positions on the oxidation resistance thin film 90.
b is in contact conduction.

A region 55 surrounded by a broken line in the drawing corresponds to a portion functioning as a hydrogen detecting portion. This hydrogen detector 55
Is formed by stacking the sensing thin film 30, the oxidation resistance thin film 90, and the electrode films 40a and 40b on the insulating substrate 310 in this order, and via circuit wiring (not shown) connected to the electrode films 40a and 40b. A detection signal is sent to an external control device (not shown).

The sensing thin film 30 contains 50% Pd as a main component.
Cr, Ni, Ag as an alloying element is added so as to have an atomic ratio of 50% or less. In addition, the sensing thin film 30 has a rectangular shape or a meandering shape having a large number of folded portions in a plane view, and has a film thickness of 5
˜100 nm. The composition and film thickness of the sensing thin film 30 are appropriately selected depending on the hydrogen concentration in the atmosphere to be detected.

The oxidation resistance thin film 90 has a thickness of 20 nm or less and covers the entire surface of the sensing thin film 30. The oxidation resistance thin film 90 is made of a conductor thin film containing a precious metal element as a main component, which is not easily oxidized in the atmosphere and has no catalytic action for hydrogen combustion. The oxidation resistance thin film 90 of this embodiment contains 99.9 atomic% of Au as a main component. As the main component of the oxidation resistance thin film 90, Pt can be used in addition to Au.

The pair of electrode films 40a and 40b are attached to both ends of the oxidation resistance thin film 90, respectively, and are connected to the electric circuit of the external detector through a wire containing Al, Au or the like as a main component. The electrode films 40a and 40b are made of Al, N
It is composed of a single-layer film containing a metal such as i, Au, Ag, Ti, Cr or the like as a main component or a multilayer film of two or more layers, and has a film thickness of 0.2 to
It was 1 μm.

In the detection section 55, the pair of electrode films 40a, 40a
The electrical resistances at both ends of b are measured, and the external detector calculates the hydrogen concentration based on this measurement signal and predetermined data. Further, the external detector is adapted to display the detected value of hydrogen concentration on the screen.

In this embodiment, hydrogen gas molecules permeate and diffuse through the very thin oxidation resistance thin film 90 in an environment without oxygen such as in an inert gas or vacuum, and further into the sensing thin film 30. Since it diffuses, a pair of electrode films 40a,
The electrical resistance between 40b changes. The hydrogen concentration can be known by detecting the change in the electric resistance.

Further, even in an environment where oxygen is present,
Similarly, since hydrogen gas molecules permeate and diffuse through the thin film 90 and diffuse inside the thin film 30, a pair of electrode films 40a and 40a are formed.
The hydrogen concentration can be known by detecting the change in electrical resistance between b.

Next, a method of manufacturing the hydrogen gas detector of this embodiment will be described.

The insulating substrate 10 has a thickness of 0.3 mm,
A borosilicate glass plate having a resistivity of 1 × 10 ⁶ Ω · m or more was used. The surface of the glass substrate 10 was washed so that harmful impurities such as metal ions and organic substances did not exist.

A surface of the substrate 10 thus treated is covered with a meandering shadow mask in a plan view, the substrate 10 is carried into a PVD apparatus, and physical chemical vapor deposition (vacuum vapor deposition) is carried out.
The Cr thin film 39, P having a thickness of 15 nm is formed on the substrate 10 by
A sensing thin film 30 mainly composed of d and having a thickness of 0.05 μm (50 nm) and an oxidation resistance thin film 90 mainly composed of Au and having a thickness of 2 nm were sequentially formed. The sensing thin film 30 has a meandering shape in a plan view.

The Cr thin film 39 has a composition of 99.9% and is an intermediate adhesion layer inserted to improve the adhesion between the sensing thin film 30 and the substrate 10. Ti may be used instead of Cr. The composition of the oxidation resistant thin film 90 is 99.9%.

Next, a pair of electrode films 40a and 40b were formed by the PVD method using a predetermined shadow mask in the vicinity of both ends of the oxidation resistance thin film 90. Electrode film 40a, 40
b is a multi-layer laminated film consisting of two layers of a Cr film having a film thickness of 15 nm and a Ni film having a film thickness of 500 nm. Furthermore, each electrode film 4
Wire leads were connected to 0a and 40b, and this was further connected to a circuit of an external control device (not shown).

The hydrogen gas detection apparatus having the detection unit 50 thus manufactured can detect hydrogen with high sensitivity even in an oxygen-free environment.

(Second Embodiment) A hydrogen gas detection apparatus according to the second embodiment will be described with reference to FIG. In addition,
Descriptions of portions of the present embodiment that overlap with the above embodiments will be omitted.

In the device of this embodiment, the conductive thin film 65 as a heat generating film is formed on the back surface of the substrate 310, which is the opposite side to the portion functioning as the hydrogen detecting portion. The material of the conductive thin film 65 is not particularly limited, and may be a substance such as a conductor or a semiconductor that allows a current to flow.

A pair of electrode films 66a and 66b were formed on the conductive thin film 65 in the vicinity of both ends. Electrode film 66a, 66
b is a single-layer film or a multi-layer film having two or more layers containing one or more selected from the group of Al, Ni, Au, Ag, Ti, and Cr as the main component. The pair of electrode films 66a and 66b are connected to a power source (not shown) via wire lead wires. When electricity is applied between the pair of electrode films 66a and 66b, Joule heat is generated in the conductive thin film 65, and this heat generation heats the hydrogen detection unit 55 (sensing thin film 30).

The glass substrate 310 has a thickness of 0.3 mm, the conductive thin film 65 is made of metal Cr, and its thickness is 500 n.
m. The electrode films 66a and 66b have a film thickness of 15 nm.
To form a two-layer film composed of the metal Cr film and the metal Ni film having a film thickness of 300 nm.

The electric resistance between the electrode films 66a and 66b is set to 30
It was set to 0Ω. When a current of 60 mA is applied between both electrodes, the hydrogen detection unit 55 can be heated to 100 ° C. and heated. When a current of 80 mA is applied between the electrodes, the hydrogen detector 55 can be heated to 150 ° C. and heated.

The external control device can obtain the electric resistance between the electrode films 40a and 40b on the basis of the signal from the detection portion 55, and can further know the hydrogen concentration from this.

Also in the present embodiment, hydrogen gas permeates and diffuses through the very thin oxidation resistance thin film 90 and diffuses inside the sensing thin film 30 in an environment without oxygen such as in an inert gas or vacuum. Since the electric resistance between the electrode films 40a and 40b changes, the hydrogen concentration can be known from this.

Further, even in an environment where oxygen is present,
Similarly, hydrogen gas permeates and diffuses through the oxidation resistance thin film 90,
Since it diffuses inside the thin film 30, the electrode films 40a, 40b
The hydrogen concentration can be known from the change in the electrical resistance between the two.

According to the apparatus of this embodiment, the hydrogen detector 5
When 5 was heated to 100 ° C., it was possible to reduce the response speed to hydrogen by a factor of 10 as compared with the first embodiment.

(Third Embodiment) A hydrogen gas detector according to a third embodiment will be described with reference to FIG. In addition,
Descriptions of portions of the present embodiment that overlap with the above embodiments will be omitted.

In the device of this embodiment, the insulating substrate 310 is used.
A conductive thin film 65 as a heat generating film is formed on the surface of the thin film, and an intermediate adhesion layer 39 and a sensing thin film 3 are formed on the conductive thin film 65 via an insulating film 77.
0 and the oxidation resistance thin film 90 are sequentially laminated. In addition,
Since the insulating film 77 is not formed on the peripheral portion of the conductive thin film 65, the conductive thin film 65 is exposed at this peripheral portion. A pair of electrode films 66a on the exposed surface of the peripheral edge portion,
The conductive film 66b is brought into contact with the conductive thin film 65 so that power is supplied to the conductive thin film 65 from a power source (not shown).

Metal Cr is used for the conductive thin film 65, and its thickness is set to 500 nm. As the insulating film 77, a silicon oxide thin film having a film thickness of 1 μm was used. The insulating film 77 is not limited to silicon oxide, but may be made of a material such as aluminum oxide.

The electric resistance between the pair of electrode films 66a and 66b was set to 300Ω. When a current of 40 mA is applied between both electrodes, the hydrogen detector 55 can be heated to 100 ° C., and when a current of 60 mA is applied, the hydrogen detector 55 can be heated to 150 ° C. I was able to.

The external control device obtains the electric resistance between the electrode films 40a and 40b based on the signal from the detection section 55, and the hydrogen concentration can be further known from this.

Also in the present embodiment, hydrogen gas permeates and diffuses through the very thin oxidation resistance thin film 90 and diffuses inside the sensing thin film 30 in an environment where there is no oxygen such as in an inert gas or vacuum. Since the electric resistance between the electrode films 40a and 40b changes, the hydrogen concentration can be known from this.

Further, even in an environment where oxygen is present,
Similarly, hydrogen gas permeates and diffuses through the oxidation resistance thin film 90,
Since it diffuses inside the thin film 30, the electrode films 40a, 40b
The hydrogen concentration can be known from the change in the electrical resistance between the two.

According to this embodiment, the hydrogen detector 55 is set to 1
When heated to 00 ° C., the response speed to hydrogen can be shortened to a tenth as compared with the device of the first embodiment, and the power consumption required for heating is higher than that of the device of the second embodiment. Was reduced to half.

(Fourth Embodiment) A hydrogen gas detection apparatus according to the fourth embodiment will be described with reference to FIG. In addition,
Descriptions of portions of the present embodiment that overlap with the above embodiments will be omitted.

In the device of this embodiment, the semiconductor substrate 10 is used as the substrate. The semiconductor substrate 10 is doped with As as an impurity and has a resistivity of 1 × 10 ⁻³ Ω · cm.
On the n-type Si single crystal substrate having a thickness of 0.5 mm.
Resistivity when doped with (phosphorus) as an impurity is 15Ω
A silicon wafer in which an n-type Si film having a thickness of 20 cm and a thickness of 20 cm was epitaxially grown was used. In this embodiment,
Two detectors 50 and 51 are formed on the silicon substrate 10.

A first insulating film 20 is formed on the front surface side (epitaxial film growth surface) of the substrate 10 so as to cover the entire surface. The first insulating film 20 contains silicon oxide as a main component and has a film thickness in the range of 500 to 1000 nm (0.5 to 1 μm).

The second detector 5 is formed on a part of the first insulating film 20.
In order to form a hole in which 1 is to be formed, a resist pattern is formed in which only the portion to be a hole is formed as an opening. After removing the first insulating film entirely in the thickness direction of the resist opening, thermal oxidation is performed. A second insulating film was formed in the opening. The conditions of thermal oxidation are 800 ° C. × 10 hours in an oxygen atmosphere having a purity of 99.9% at atmospheric pressure. On the second insulating film 21 existing at the bottom of the hole, Pd is the main component and C
A second sensing thin film 31 is formed by alloying r, Ni, or Ag so that the atomic ratio is 50% or less. Further, a second oxidation resistance thin film 91 is formed on the second sensing thin film 31. A single electrode film 41 is in contact with the second oxidation resistance thin film 91 at an appropriate position.

The second sensing thin film 31 is substantially the same in material and film thickness as the first sensing thin film 30 described above.
The oxidation resistance thin film 91 is substantially the same in material and thickness as the first oxidation resistance thin film 90.

The electrode films 40a, 40b and 41 are made of Al, N
i, Au, Ag, Ti, Cr consisting of a single layer film or a multilayer film of two or more layers containing one or more selected from the group as a main component, and the film thickness is in the range of 0.2 to 1 μm. .

A back surface electrode film 43 is formed on the back surface side of the substrate 10 so as to cover the entire surface. The back electrode film 43 is the first
And the electrode films 40a, 40b of the second detectors 50, 51,
The material and the film thickness are substantially the same as those of No. 41.

The first detector 50 has a film thickness of 500 to 100.
On the first insulating film 20 of 0 nm (0.5 to 1 μm),
The intermediate adhesion layer 39, the first sensing thin film 30, the first oxidation resistance thin film 90, and the pair of electrode films 40a and 40b are sequentially laminated. The first sensing thin film 30 has a rectangular shape or a meandering shape with a large number of folded portions, which is made of a material containing Pd as a main component and Cr, Ni, or Ag alloyed to have an atomic ratio of 40% or less. 20-100n
It has a film thickness of m. The first oxidation resistant thin film is Pt or A
u is the main component, and the film thickness is 20 nm or less. The pair of electrode films 40a and 40b are in contact with each other in the vicinity of both ends of the first oxidation resistance thin film 90 and are formed of a single layer or a multilayer film having a film thickness of 0.2 to 1 μm.

The second detector 51 has a film thickness of 20 to 150 n.
The second sensing thin film 31 and the second oxidation resistance thin film 91 are sequentially laminated in the hole on the second insulating film 21 of m, while the first sensing film 20 outside the hole is formed on the first insulating film 20. The second sensing thin film 31, the second oxidation resistance thin film 91, and the second electrode film 41 are sequentially laminated.

According to the apparatus of this embodiment, the hydrogen concentration can be known by measuring the electric resistance between the pair of electrode films 40a and 40b in the first detection section 50, and the second detection section 51 can be obtained. In, the hydrogen concentration can be known by measuring the electrostatic capacitance between the front surface side electrode film 41 and the rear surface side electrode film 43.

Next, a method of manufacturing the hydrogen gas detector of this embodiment will be described.

First, the oxide film naturally formed on the surface of the silicon substrate 10 was removed by wet etching to clean the substrate surface.

Next, the first insulating film 20 was formed on the surface side of the substrate 10 by a chemical vapor deposition method (CVD method) using monosilane and oxygen diluted with an inert gas as source gases. In this embodiment, the first insulating film 20 is made of SiO 2 with a film thickness of 1 μm.
_Two films were formed. This insulating film forming step is performed by a chemical vapor deposition method using monosilane and nitrous oxide as source gases, and TEO.
It can also be formed by a chemical vapor deposition method using S or oxygen as a source gas, TEOS, a chemical vapor deposition method using ozone as a source gas, a chemical vapor deposition method by thermal decomposition of TEOS, or an RF sputtering method.

Next, a silane coupling agent for increasing the adhesiveness of the photoresist and a photoresist are sequentially coated on the SiO ₂ film of the substrate, and the resist coating film is pattern-exposed and developed. As a result, a predetermined mask pattern having an opening for forming the second insulating film 21 was obtained. The size of the opening of the mask pattern is, for example, 0.5 mm × 0.5 mm.

SiO exposed at the opening of the mask pattern
Only _two films were selectively removed by the wet etching method.
The wet etching conditions were immersion at room temperature for 5 minutes using a mixed aqueous solution of hydrogen fluoride and ammonium fluoride. A plasma dry etching method may be used instead of the wet etching method.

The photoresist used as the mask pattern was washed and removed with a solvent such as acetone. After removing the resist, the surface was cleaned by irradiating it with ultraviolet rays in the atmosphere and exposing it to ozone generated in the irradiation part. Note that oxygen plasma exposure may be performed instead of ozone exposure.

Next, the insulating film 21 was formed by oxidizing Si in the holes provided by heat treatment in an oxygen atmosphere. The oxide film thickness is 20 nm. Next, a photoresist was applied to the entire front surface and the oxide film formed when the insulating film 21 was formed on the back surface side of the substrate 10 was removed by wet etching.

Next, the back surface electrode 43 is formed so as to cover the back surface of the substrate 10. In this embodiment, the back electrode 43 is formed by sequentially stacking a three-layer film of Ti having a film thickness of 100 nm, Al having a film thickness of 200 nm, and Ni having a film thickness of 500 nm by a vacuum evaporation method.
And In this way, it is possible to make ohmic contact with the Si substrate 10. The back electrode 43 can also be formed by a sputtering method.

The photoresist film on the substrate surface side was removed by washing with acetone. After removing the resist, the substrate surface was cleaned by irradiating it with ultraviolet rays in the atmosphere and using ozone generated in the irradiation part. The same effect can be obtained by performing oxygen plasma exposure instead of ozone exposure.

In this embodiment, a shadow mask made of stainless steel foil is used to form an intermediate adhesion layer 39 made of a Cr film having a thickness of 15 nm, and the atomic ratio of the thickness of 50 nm is 10% Cr and 90%.
A first sensing thin film 30 made of PdCr alloy containing Pd and an oxidation resistance film 90 made of Au were sequentially formed by a vacuum deposition method. The location where the first sensing thin film 30 is formed is
This is the upper surface of the first insulating film 20 having a film thickness of 1 μm. The mask has a serpentine shape having a width of 1 mm and a plurality of folded portions having a length of 200 mm. Film thickness 15nm
The intermediate adhesion layer 39 made of the Cr film is used as the first sensing thin film 30.
It is inserted to improve the adhesion of
The same effect can be obtained by inserting a Ti film instead of the r film.
A mask may be used in which a photoresist is applied, a photomask is used for partial exposure, and the photosensitive portion is removed by a development process. According to this method, a finer line width can be obtained. Alternatively, after forming a thin film on the entire surface of the substrate by a vacuum deposition method, a resist pattern is formed by an exposure / development process using a photoresist and a photomask, and unnecessary portions are removed by a wet or dry etching method. A pattern can also be formed. Further, the first Pd thin film 30 can also be formed by a sputtering method. Furthermore, the first Pd
The component of the thin film 30 is Pd as a main component, and Cr, Ni, Ag
It is also possible to use an alloy prepared by, for example, having any composition.

A film thickness of 50 is obtained by using the same method as the above process.
A second sensing thin film 31 made of an alloy of 10% Cr and 90% Pd in an atomic ratio of nm and an oxidation resistance film 91 made of Au were sequentially formed by a vacuum deposition method. This second Pd
The portion where the thin film 31 is formed is the second Si having a film thickness of 20 nm.
The first S having a thickness of 1 μm (1000 nm) from the O ₂ insulating film 21
It extends to the iO ₂ insulating film 20.

A film thickness of 15 is obtained by using the same method as the above process.
The electrodes 40a, 40b and 41 each having a two-layer structure of a Cr film of 50 nm and a Ni film of 500 nm were laminated.
That is, the pair of electrodes 40a and 40b are formed in the first meandering shape.
Was formed on both ends of the sensing thin film 30 of FIG. The first detection unit 50 was formed by connecting the pair of electrodes 40a and 40b to an external circuit (not shown) with a lead wire. Further, the single electrode 41 was formed on the second sensing thin film 31. The second detection portion 51 was formed by connecting the front surface side electrode 41 and the back surface electrode 43 to an external circuit (not shown) with a lead wire.

The hydrogen gas detection device provided with the first and second detectors 50 and 51 thus manufactured is capable of detecting hydrogen with high sensitivity even in an oxygen-free environment. is there.

Next, referring to FIG. 5, the detection operation characteristics of the first detection section of this embodiment will be described in comparison with those of the conventional product.

In FIG. 5, the horizontal axis represents hydrogen concentration (volume%),
It is a characteristic diagram which shows the result of having investigated resistance value change (relative value) on the vertical axis | shaft, and investigated the correlation of both. In the figure, a characteristic line A shows the result of a measurement example in the apparatus of the present embodiment in an environment in which hydrogen gas is mixed with nitrogen at atmospheric pressure and oxygen is not present at all, and a characteristic line B is air at atmospheric pressure. The result of the measurement example in the apparatus of the present embodiment is shown in an environment in which hydrogen gas is mixed in and oxygen is present in an amount of 20% by volume. Characteristic line C shows that hydrogen gas is mixed in air at atmospheric pressure and oxygen is 20 15 shows the results of measurement examples in the conventional apparatus shown in FIG. 14 under the environment in which the volume% exists. The relationship between the hydrogen concentration and the electric resistance of the detection part is shown, and changes are shown with the resistance value when hydrogen is not present as 1 (reference value).

In the characteristic line A (oxygen-free environment), the resistance value increased due to exposure to hydrogen, and it was possible to detect hydrogen at a concentration of 5% or more even in an oxygen-free environment. Also, the concentration is 100
The element did not break down even when exposed to% hydrogen, and showed the same hydrogen detection performance for hydrogen in a vacuum.

In the characteristic line B (aerobic environment), similarly to the characteristic line A, the resistance value increased due to hydrogen exposure, and hydrogen could be detected even in an environment where oxygen was present. However, there was a risk of explosion, so measurements were performed only at hydrogen concentrations of less than 3%.

In the characteristic line C, the resistance value did not change even after exposure to hydrogen, and hydrogen could not be detected in an environment where oxygen was present. In this case as well, there was a risk of explosion, so measurement was performed only at a hydrogen concentration of less than 3%.

Next, the operating characteristics of the second detector will be described with reference to FIG.

In FIG. 6, the horizontal axis represents hydrogen concentration (ppm),
It is a characteristic diagram which shows the result of having investigated the correlation of both by taking electrostatic capacity (relative value) on the vertical axis. A change in the capacitance of the second detector 51 (capacitance between the electrodes 41 and 43) was measured in an oxygen-free environment where only a small amount of hydrogen gas was added and mixed in nitrogen gas at atmospheric pressure. Specifically, the hydrogen concentration is 0 to 1
A constant voltage of 0.5 V was applied between the electrodes 41 and 43 with various changes within the range of 000 ppm, and the electrostatic capacitances at that time were measured.

Characteristic line D shows the result of a measurement example in the apparatus of this embodiment in an atmosphere in which hydrogen gas was mixed in nitrogen at atmospheric pressure and oxygen was not present at all, and characteristic line E was in air at atmospheric pressure. The result of the measurement example in the device of the present embodiment in the environment in which hydrogen gas is mixed and oxygen is present at 20% by volume is shown.

The relationship between the hydrogen concentration and the electrostatic capacity is shown. A voltage of 0.5 V is applied to the element 41 to the electrode 41, and the electrostatic capacity of the detector (electrodes 41-43 in FIG. 4) is shown. The electrostatic capacitance between) was measured.

As is clear from the figure, in this detecting section, the electrostatic capacity increases due to hydrogen exposure even in an oxygen-free environment or in an oxygen-containing environment, and the capacitance of 150 p
It has detection sensitivity even for extremely low concentrations of hydrogen below pm. Further, the element did not break down even when exposed to hydrogen having a concentration of 100%, and showed the same hydrogen detection performance for hydrogen in a vacuum.

In the second detector 51 of this embodiment, when exposed to hydrogen, hydrogen diffuses inside the sensing thin film 31 containing Pd as a main component, and an electric dipole is formed at the interface with the insulating film 21. Therefore, it is measured as an increase in capacitance.

According to the present invention, since the hydrogen gas detector is composed of two kinds of detectors, high sensitivity can be obtained even in an oxygen-free environment or an environment in which oxygen is present. And it can measure even high concentration hydrogen.

(Fifth Embodiment) Next, a hydrogen gas detection apparatus according to a fifth embodiment will be described with reference to FIG. It should be noted that the description of the portions of the present embodiment that overlap the above-described embodiments will be omitted.

In the device of this embodiment, the insulating film 60 was formed in contact with the back surface electrode 43, and the conductive thin film 61 was further formed on the insulating film 60. The back surface insulating film 60 has a film thickness of 1 μm (1
(000 nm) of silicon oxide, and the back surface conductive thin film 61 is a heating element made of Ni—Cr alloy, Cr or the like, and receives power from a power source via an electrode (not shown).

In the hydrogen detecting device according to this embodiment, the element temperature is raised by Joule heat generated by passing an electric current through the heating element 61, and the response speed when exposed to hydrogen is improved. In this embodiment, the temperature of the device is 6
A temperature measuring element (not shown) was provided in order to keep the temperature constant at an arbitrary temperature in the range of 0 to 100 ° C., and a mechanism for adjusting the current flowing through the heating element was provided for control. In this way, the diffusion rate of hydrogen in the sensing thin films 30 and 31 containing Pd as the main component was increased, and the time required for hydrogen leak detection could be shortened to about one tenth.

(Sixth Embodiment) A hydrogen gas detection apparatus according to the sixth embodiment will be described with reference to FIG. In addition,
Descriptions of portions of the present embodiment that overlap with the above embodiments will be omitted.

In the apparatus of this embodiment, a third detecting section 52 is added to the first and second detecting sections 50 and 51 of the apparatus of the fourth embodiment. The third detector 52 is
It has the same structure as the second detector 51, but the Si substrate 10
Third insulating film 22 having silicon oxide as a main component formed thereon
Film thickness is different. That is, the thickness of the third insulating film 22 is set to 1.5 to 3.0 nm, which is smaller than the thickness of the second insulating film 21.

After exposing the surface of the Si substrate 10, the third insulating film 22 is immersed in a mixed solution of sulfuric acid and hydrogen peroxide, washed with ultrapure water, and then irradiated with ultraviolet rays in the atmosphere. It is formed by exposure to ozone that is generated. The thickness of the third insulating film 22 thus formed is about 2 nm. The ozone exposure condition was irradiation of ultraviolet rays for 60 minutes in the atmosphere.

The same insulating film 22 can be obtained by exposing to oxygen plasma instead of ozone exposure. The oxygen plasma exposure conditions are as follows: the substrate to be processed is placed between parallel plate electrodes facing each other with a distance of φ400 mm and 35 mm, and plasma is generated by RF discharge of 13.56 MHz in an oxygen atmosphere of 0.5 Torr. , 1 at RF output 300W
The processing time is 0 minutes.

FIG. 9 shows the result of examination on an example of hydrogen gas detection by the third detector 52 according to this embodiment. In the figure, a characteristic line F shows the result of a measurement example in the present embodiment in an environment in which hydrogen gas is mixed with nitrogen at atmospheric pressure and oxygen is not present at all, and a characteristic line G is air at atmospheric pressure. The result of the measurement example in the present example in the environment in which hydrogen gas is mixed therein and oxygen is present at 20% by volume is shown.

Minus 0.5 V with respect to the electrode 43 of the element
The current flowing when the voltage is applied to the electrode 42 is measured, and the relationship between the hydrogen concentration and the current is shown.

In this detection section, the current value increases due to hydrogen exposure even in an oxygen-free environment or in an environment where oxygen is present, and it has sensitivity to low-concentration hydrogen of 1300 ppm or less. . Further, the element did not break down even when exposed to hydrogen having a concentration of 100%, and showed the same hydrogen detection performance for hydrogen in a vacuum.

In the third detector 52 of this embodiment, when exposed to hydrogen, hydrogen diffuses into the sensing thin film 32 containing Pd as a main component, and lowers the potential barrier at the interface with the insulating film 22. Therefore, it is measured as an increase in current.

According to the present embodiment, since the hydrogen gas detector is composed of three types of detectors, it has high sensitivity even in an oxygen-free environment or an oxygen-containing environment. Moreover, even high concentration hydrogen can be measured.

(Seventh Embodiment) The seventh embodiment will be described with reference to FIG.
The hydrogen gas detection device of the embodiment will be described. In the present embodiment, the hydrogen gas detection device described above is used in a liquefied hydrogen storage container to construct a hydrogen leakage detection system for detecting hydrogen gas leakage.

In FIG. 10, reference numeral 111 is a liquid hydrogen storage container, and reference numeral 122 is a vacuum heat insulating container. Reference numerals 161a to 161
f is a hydrogen gas detection device according to the present invention, and reference numerals 171a-1
Reference numeral 71f is an electric wire for transmitting a signal, which is connected to the control device 180 outside the container without breaking the vacuum.

According to the hydrogen leak detection system of this embodiment, the vacuum heat insulating container 12 that cannot be sampled is used.
Since the inside of 2 can be detected, it is possible to accurately determine whether hydrogen is leaking or the atmosphere is leaking into the vacuum heat insulating container.

[0106]

According to the present invention, regardless of the presence of oxygen, even in an environment without oxygen such as in an inert gas atmosphere or in outer space, or in an environment with oxygen, regardless of the presence of oxygen. Since hydrogen gas can be detected with high sensitivity, leakage of hydrogen gas generated in the liquefied hydrogen storage container or the compressed hydrogen storage container can be detected rapidly with high sensitivity and in a high concentration range. Therefore, the safety and reliability of these hydrogen gas facilities can be significantly improved.

The device of the present invention not only functions for various equipments on the earth in the atmosphere, but is also effective for various equipments on outer space, the moon surface, or other planets under anoxic atmosphere. As it works, it has a wide range of uses.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view showing a hydrogen gas detection device according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a hydrogen gas detection device according to a second embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view showing a hydrogen gas detection device according to a third embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view showing a hydrogen gas detection device according to a fourth embodiment of the present invention.

FIG. 5 is a characteristic diagram showing a correlation between changes in resistance value and hydrogen concentration.

FIG. 6 is a characteristic diagram showing a correlation between electrostatic capacity (relative value) and hydrogen concentration (volume%).

FIG. 7 is an enlarged cross-sectional view showing a hydrogen gas detection device according to a fifth embodiment of the present invention.

FIG. 8 is an enlarged sectional view showing a hydrogen gas detection device according to a sixth embodiment of the present invention.

FIG. 9 is a characteristic diagram showing a correlation between current (relative value) and hydrogen concentration.

FIG. 10 is a configuration block diagram schematically showing a liquefied hydrogen storage container to which a hydrogen gas detection device of the present invention is attached as a seventh embodiment.

FIG. 11 is a configuration block diagram schematically showing a conventional leak detection system in a compressed hydrogen storage container installed in an explosion-proof atmosphere.

FIG. 12 is a configuration block diagram schematically showing another conventional leak detection system in a liquefied hydrogen storage container installed in an explosion-proof atmosphere.

FIG. 13 is a configuration block diagram schematically showing another conventional leak detection system in a liquefied hydrogen storage container installed in a vacuum heat insulating container.

FIG. 14 is an enlarged cross-sectional view showing the outline of a conventional hydrogen gas detection device.

[Explanation of symbols]

10 ... Semiconductor substrate (Si substrate), 310 ... Insulating substrate (glass substrate), 20 ... First insulating film, 21 ... Second insulating film, 22 ... Third insulating film, 30, 31, 32 ... Sensing Thin film (Pd film) 39 ... Intermediate adhesion layer (Cr or Ti film), 40a, 40b, 41, 42, 66a, 66b ... Electrode film, 43 ... Back surface electrode, 50 ... First detection part, 51 ... Second Detecting unit, 52 ... Third detecting unit, 60, 77 ... Insulating film, 61, 65 ... Exothermic film (conductive film), 90, 91, 92 ... Oxidation resistance thin film (Au film, Pt film), 111 ... Liquefaction Hydrogen storage container, 122 ... Vacuum heat insulation container, 161a-161f ... Hydrogen gas detection device, 171a-171f ... Wiring, 180 ... Control device.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuji Nomaru             Mitsubishi Heavy, 10 Oemachi, Minato-ku, Nagoya-shi, Aichi             Industrial Co., Ltd. Nagoya Aerospace System Production             In-house (72) Inventor Akihisa Okuda             Mitsubishi Heavy, 10 Oemachi, Minato-ku, Nagoya-shi, Aichi             Industrial Co., Ltd. Nagoya Aerospace System Production             In-house (72) Inventor Sumio Okuyama             4-3-16 Jonan, Yonezawa City, Yamagata Prefecture Yamagata University             Undergraduate (72) Inventor Tomonori Kumagai             4-3-16 Jonan, Yonezawa City, Yamagata Prefecture Yamagata University             Undergraduate (72) Inventor Katsuro Okuyama             4-3-16 Jonan, Yonezawa City, Yamagata Prefecture Yamagata University             Undergraduate F term (reference) 2G046 AA05 BA01 BA09 BB02 BB04                       BC05 BC09 BE03 BE08 BF01                       DB05 DC14 EA02 EA04 EA09                       EA11 FB00 FE00 FE02 FE03                       FE10 FE11 FE25 FE29 FE31                       FE38 FE44                 2G060 AA01 AA20 AB03 AE19 AF10                       AG11 AG15 BB09 HA02 HC10                       JA01

Claims (23)

[Claims] 1. A hydrogen gas detection device for detecting the concentration of hydrogen gas under both anoxic environment and aerobic environment, which is provided on an insulating substrate and one surface of the insulating substrate. A hydrogen gas detection device comprising: a sensing thin film containing Pd as a main component; and an oxidation resistance thin film provided on the sensing thin film, the oxidation resistance thin film containing a metal element that is difficult to be oxidized in the atmosphere as a main component. apparatus. 2. The device according to claim 1, wherein the oxidation resistant film is made of either Pt or Au. 3. The sensing thin film contains 50 at% or less of one or more additives selected from the group of Cr, Ni, Ag, and the balance being Pd and inevitable impurities. The device according to claim 1. 4. A conductive heat generating film provided on the other surface of the insulating substrate, an electrode film conducting to the heat generating film, and power supply to the heat generating film through the electrode film. Means for causing the heat generating film to generate resistance heat by power supply from the power supply means, and the heat generating film heats the sensing thin film through the insulating substrate. Equipment. 5. A detection unit is further provided, which comprises an electrode film that is in contact with the sensing thin film and is electrically connected to the sensing film, and a measuring circuit connected to the electrode film. The sensing unit detects the electrical resistance of the sensing thin film. The device according to any one of claims 1 to 4, characterized in that: 6. A conductive heat-generating film provided between the insulating substrate and the sensing thin film, and the heat-generating film inserted between the heat-generating film and the sensing thin film to form the sensing thin film. An insulating film that insulates from the electrode, an electrode film that is electrically connected to the heat generating film, and means for supplying power to the heat generating film through the electrode film,
2. The heat generating film is resistively heated by the power supply from the power supply means, and the heat generating film heats the sensing thin film through the insulating film.
The described device. 7. The detector is configured by inserting a thin film containing Cr or Ti as a main component and having a film thickness of 50 nm or less between the insulating substrate and the sensing thin film.
Described device 8. A hydrogen gas detection device for detecting the concentration of hydrogen gas in both anoxic environment and aerobic environment, which is provided on a semiconductor substrate and on one surface of the semiconductor substrate. First and second insulating films, a first sensing thin film containing Pd as a main component provided on the first insulating film, and in the atmosphere provided on the first sensing thin film. A first detector having a first oxidation resistant thin film containing a metal that is difficult to be oxidized as a main component; the first detector measuring the electrical resistance of the first sensing thin film; A second sensing thin film having Pd as a main component, which is provided on the insulating film, and a second oxidation resistance having a metal, which is not easily oxidized in the atmosphere, provided on the second sensing thin film as a main component A thin film and a conductor ohmic-connected to the other surface of the semiconductor substrate. Second having a back surface electrode
Of the second electrode and the second electrode of the back electrode and the second electrode.
Measuring a capacitance of the second sensing thin film by applying a voltage between the sensing thin film and the second sensing thin film. 9. The first and second oxidation resistant films are made of Pt.
2. The device according to claim 1, wherein the device comprises either Au or Au. 10. The first and second sensing films are C
The apparatus according to claim 1, which contains 50 at% or less of one or more additives selected from the group of r, Ni, and Ag, and the balance is Pd and inevitable impurities. 11. The thickness of the first insulating film is 300 nm.
The device according to claim 8, wherein the device is as described above. 12. The thickness of the second insulating film is 20 to 15
9. Device according to claim 8, characterized in that it is in the range of 0 nm. 13. The device according to claim 8, wherein the semiconductor substrate is mainly composed of silicon. 14. The device according to claim 8, wherein the first and second insulating films contain silicon oxide as a main component. 15. A first detector is formed by inserting a thin film containing Cr or Ti as a main component and having a film thickness of 50 nm or less between the first insulating film and the first sensing thin film. 9. The device according to claim 8, characterized in that 16. The apparatus according to claim 8, further comprising a conductive heating film on the other surface of the semiconductor substrate. 17. A third insulating film provided on one surface of the semiconductor substrate, and a third sensing thin film containing Pd as a main component provided on the third insulating film. It is composed of a third oxidation resistance thin film, which is provided on the third sensing thin film and has a metal element which is difficult to be oxidized in the atmosphere as a main component, and a conductor which is ohmic-connected to the other surface of the semiconductor substrate. The device according to claim 8, further comprising a third detection unit having a back electrode. 18. The apparatus according to claim 17, further comprising means for applying a voltage between the third sensing thin film and the back electrode of the semiconductor substrate. 19. The thickness of the third insulating film is 1.0 to
18. A device according to claim 17, characterized in that it is in the range of 3.0 nm. 20. The device according to claim 17, wherein the third insulating film contains silicon oxide as a main component. 21. The device according to claim 17, wherein the semiconductor substrate contains silicon as a main component. 22. A method of manufacturing a hydrogen gas detection device for detecting the concentration of hydrogen gas in an oxygen-free environment, comprising: (a) forming a first insulating film on which a first insulating film is formed on a silicon substrate. And (b) after completely removing the first insulating film in the depth direction by pattern etching, a second insulating film is formed on the exposed portion of the opening to form a second detecting portion. A shallow hole to be formed is formed, and the first insulating film is completely removed in the depth direction to expose a part of the surface of the silicon substrate to form a third hole.
And (c) forming a third insulating film by exposing the exposed surface of the silicon substrate in the deep hole to ozone to oxidize it. d) A first layer containing Pd as a main component on the first insulating film.
Is formed through an adhesion layer containing Cr or Ti as a main component, and a second sensing thin film containing Pd as a main component is formed on the second insulating film. Forming a third sensing thin film containing Pd as a main component on the insulating film of (1), and (e) including the first sensing thin film having a metal element which is difficult to be oxidized in the atmosphere as a main component on the first sensing thin film. Forming a second oxidation resistant thin film on the second sensing thin film, and forming a second oxidation resistant thin film mainly composed of a metal element which is difficult to be oxidized in the atmosphere on the second sensing thin film. A step of forming a third oxidation resistance thin film containing a metal element which is difficult to be oxidized in the atmosphere as a main component, and (f) a first oxidation resistance thin film formed of a conductor ohmic-connected on the first oxidation resistance thin film. An electrode is formed and an ohmic contact is formed on the second oxidation resistance thin film. Forming a second electrode made of a conductor electrically connected to each other, and forming a third electrode made of an ohmic-connected conductor on the third oxidation resistance thin film, (g) And a step of forming a back electrode made of an ohmic-connected conductor on the back surface of the silicon substrate. 23. A method of manufacturing a hydrogen gas detection device for detecting the concentration of hydrogen gas in an oxygen-free environment, comprising: (A) forming a first insulating film on which a first insulating film is formed on a silicon substrate. And (B) after patterning etching to completely remove the first insulating film in the depth direction, a second insulating film is formed on the exposed portion of the opening to form a second detecting portion. Forming a shallow hole to be formed, and removing the first insulating film entirely in the depth direction to expose a part of the surface of the silicon substrate to form a third hole.
And (C) forming a third insulating film by exposing the exposed surface of the silicon substrate in the deep hole to oxygen plasma to oxidize it. (D) A first layer containing Pd as a main component on the first insulating film
Is formed through an adhesion layer containing Cr or Ti as a main component, a second sensing thin film containing Pd as a main component is formed on the second insulating film, and the third thin film is formed. Forming a third sensing thin film containing Pd as a main component on the insulating film; and (E) a first sensing film containing a metal element which is hard to be oxidized in the atmosphere as a main component on the first sensing thin film. An oxidation resistance thin film is formed, a second oxidation resistance thin film containing a metal element that is difficult to be oxidized in the atmosphere as a main component is formed on the second sensing thin film, and the oxidation thin film is formed on the third sensing thin film. A step of forming a third oxidation resistance thin film containing a metal element which is difficult to be oxidized in the atmosphere as a main component, and (F) a first electrode made of a conductor ohmic-connected on the first oxidation resistance thin film. And forming an ohmic contact on the second oxidation resistant thin film. Forming a second electrode made of a conductively connected conductor and forming a third electrode made of an ohmicly connected conductor on the third oxidation resistance thin film, and (G) the silicon And a step of forming a back electrode made of an ohmic-connected conductor on the back surface of the substrate.