JP2008209373A - Modified hydrogen gas detecting semiconductor sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a modified hydrogen gas detecting semiconductor sensor for improving a lifetime and an initial sensitivity to the hydrogen gas. <P>SOLUTION: The invention is the hydrogen gas detecting semiconductor sensor including: a catalytic metal layer (1); a semiconductor layer (2); and an insulating layer (3) disposed between the catalytic metal layer (1) and the semiconductor layer (2). The catalytic metal layer (1) includes an outer face (4), and an inner face (7) containing at least one hydrogen atomic adsorption surface (8). The hydrogen atomic adsorption surface (8) is disposed adjacent to the insulating layer (3). A surface area of the outer face (4) is larger than the entire surface area of at least one hydrogen atomic adsorption surface (8) by at least 100%. The invention is associated with a probe including the sensor, a hydrogen gas detection system including the sensor, and a usage of the sensor for detecting the existence and/or measuring a concentration of the hydrogen gas in a gas sample. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydrogen gas sensing semiconductor sensor according to the preamble of claim 1. Furthermore, the present invention is in accordance with the present invention for measuring the concentration of hydrogen gas molecules in a gas sample, as well as using a hydrogen gas sensitive semiconductor sensor according to the present invention to detect the presence of hydrogen gas molecules in a gas sample. It relates to using a hydrogen gas sensitive semiconductor sensor. Furthermore, the present invention relates to a probe including a hydrogen gas sensing semiconductor sensor according to the present invention and a hydrogen gas detection system including a hydrogen gas sensing semiconductor sensor according to the present invention.

  Detection of specific gas atoms or molecules in a gas sample is currently done from complex technical systems such as mass spectrometers and gas chromatographs, for example, small and relatively simple sensors such as sensors that measure the thermal conductivity of gases. Can be implemented using any of a number of different devices. While most of these devices are based on measuring the physical or chemical properties of gas atoms or molecules, some of these instead are the actual presence of a particular gas atom or molecule. Some are based on measuring.

  For example, U.S. Pat. No. 6,057,051 describes an apparatus that can be used for the detection of specific gas molecules in a gas sample and is based on measuring the actual presence of specific gas molecules. More specifically, Patent Document 1 describes a gas sensor that can be used to detect hydrogen gas.

  There are a variety of applications where the use of an apparatus for detecting hydrogen gas is necessary, useful or desirable. For example, such an apparatus may be used as a leak detector for systems using hydrogen gas, as a leak detector for systems and methods using hydrogen gas as a tester and / or as a tracer gas for locating leaks, or for example, hydrogen It can be used as an alarm detector for indicating the presence of hydrogen gas in the industry (petrochemical industry, electrochemical industry, gas factory, etc.) using gas or hydrogen gas-containing gas mixture for the purpose of preventing explosion.

  The gas detection sensor described in Patent Document 1 includes a catalytic metal layer that forms a metal electrode, a semiconductor layer, and an insulating layer disposed between the catalytic metal layer and the semiconductor layer. Since this sensor includes a semiconductor structure, it is referred to herein as a gas sensitive semiconductor sensor. The catalytic metal layer is made of either the platinum metals palladium, nickel and platinum, or an alloy containing at least 20% palladium in atomic weight.

  The operation principle of the semiconductor sensor of Patent Document 1 for detecting hydrogen gas is based on the following facts. That is, some of the platinum metals, particularly palladium, adsorb hydrogen gas molecules on the surface, dissociate and decompose the adsorbed hydrogen gas molecules, and allow the penetration of hydrogen atoms formed in this way, This means that hydrogen atoms can be adsorbed on the surface. The term “catalytic metal” is used herein to denote a metal or alloy that can dissociate hydrogen gas molecules and absorb the hydrogen atoms thus formed.

  Here, the basic operation principle of the semiconductor sensor of Patent Document 1 will be described with respect to a case where the sensor is used for detection of hydrogen gas. When the semiconductor sensor of Patent Document 1 is exposed to hydrogen gas molecules, the catalytic metal layer can adsorb some molecules on its outer surface configured to communicate freely with the surrounding atmosphere. Next, the adsorbed hydrogen gas molecules are dissociated on the outer surface, and the hydrogen atoms thus formed can be absorbed by the catalytic metal layer. Subsequently, some of the absorbed hydrogen atoms are adsorbed at the interface between the catalytic metal layer and the insulating layer after diffusion through the catalytic metal layer.

  Furthermore, it has been sufficiently confirmed that hydrogen atoms adsorbed at the interface between the catalytic metal layer and the insulating layer are polarized and the positive side faces the insulating layer (Non-Patent Document 1). Polarization means that a hydrogen dipole is generated. The hydrogen dipole generates an electric field that shifts the effective work function of the catalytic metal layer. As a result of the shift of the effective work function of the catalytic metal layer, the electrical function of the semiconductor sensor is affected. That is, a voltage shift is generated in the characteristics of the semiconductor sensor, and this effect is used for detection of hydrogen gas. This sensing principle is referred to herein as the “hydrogen dipole transducer principle”.

  The shift in the effective work function of the catalytic metal layer, generated by hydrogen atoms adsorbed at the interface between the catalytic metal layer and the insulating layer, is not only for detecting the presence of hydrogen gas in the gas sample, but also for the gas sample. It can also be used to measure the concentration of hydrogen gas in The magnitude of the shift is determined by the number of hydrogen atoms adsorbed per unit area, that is, the density of hydrogen atoms at the interface between the catalytic metal layer and the insulating layer. Since the amount of hydrogen gas molecules in the gas sample and the amount of hydrogen atoms adsorbed at the interface between the catalytic metal layer and the insulating layer equilibrate after a certain time, the magnitude of the equilibrium shift is determined by the amount of hydrogen gas in the gas sample. It can be used as a reference for the concentration of molecules. However, the time to equilibrium achieved between the amount of hydrogen gas molecules in the gas sample and the amount of hydrogen atoms adsorbed at the interface between the catalytic metal layer and the insulating layer is usually relatively long. For that reason, it is preferable to use the rate at which the effective work function shifts, that is, the rate at which the output signal shifts, before the equilibrium shift is achieved, as a measure of the concentration of hydrogen gas molecules in the gas sample. Furthermore, the magnitude of the effective work function shift rate and the equilibrium shift at a given concentration of hydrogen gas molecules in the gas sample will, of course, depend on the sensitivity of the sensor to hydrogen gas molecules.

  A hydrogen gas sensing semiconductor sensor operating based on the same operating principle as the sensor of Patent Document 1, that is, based on the so-called hydrogen dipole transducer principle, is referred to herein as “hydrogen operating based on the hydrogen dipole transducer principle”. Displayed as “Gas Sensing Semiconductor Sensor”.

  Hydrogen gas sensitive semiconductor sensors operating on the hydrogen dipole transducer principle are known to have very high selectivity for hydrogen gas when operating at temperatures up to about 150 ° C. However, such sensors have also been shown to be sensitive to other gaseous hydrogen-containing molecules such as alcohols and unsaturated hydrocarbons when operating at higher temperatures. For example, the sensitivity to methanol and ethanol of a sensor operating based on the hydrogen dipole transducer principle when operating at a temperature exceeding 150 ° C. has been shown (Non-Patent Document 2). Next, in the same manner as hydrogen gas molecules, such gaseous hydrogen-containing molecules are adsorbed and dissociated on the outer surface of the catalyst metal layer, and the hydrogen atoms thus formed are absorbed by the catalyst metal layer.

  Therefore, a semiconductor sensor operating based on the hydrogen dipole transducer principle can be used not only for the detection of hydrogen gas molecules but also for the detection of other gaseous hydrogen-containing molecules. However, if such sensors are to be utilized for hydrogen gas detection, these sensors are operated at temperatures below 150 ° C. to obtain the highest possible selectivity for hydrogen gas, and more It is preferable to avoid sensitivity to other gaseous hydrogen-containing molecules that make the sensor sensitive when operating at high temperatures.

  The specific sensitivity of hydrogen gas molecules to specific hydrogen gas sensing semiconductor sensors that operate on the basis of the hydrogen dipole transducer principle is formed by the catalytic properties of the catalytic metal layer, i.e., dissociating hydrogen gas molecules on the outer surface. Depends on the ability of the catalytic metal layer to absorb hydrogen atoms. The reason why the catalytic properties of the catalytic metal layer affect the sensitivity is, of course, that the properties of the catalytic metal layer and the number of hydrogen atoms that can be adsorbed per unit area, i.e. at a certain concentration of hydrogen gas in the gas sample. It affects the density of hydrogen dipoles at the interface with the insulating layer.

  However, the sensitivity of a hydrogen gas sensitive semiconductor sensor operating on the hydrogen dipole transducer principle can be reduced, for example, by oxidation on the outer surface of the catalytic metal layer. Oxygen around the semiconductor sensor can be adsorbed or bound to the outer surface of the catalytic metal layer. And the number of the adsorption | suction locations which can adsorb | suck a hydrogen gas molecule on the outer surface of a catalyst metal layer is reduced simultaneously with the number of oxygen molecules and atoms increasing on the outer surface of a catalyst metal layer. When the number of adsorption sites where hydrogen gas molecules can be adsorbed is reduced, the number of hydrogen gas molecules that can be adsorbed and dissociated on the outer surface of the catalyst metal layer and the catalyst metal layer are absorbed at a certain concentration of hydrogen gas in the gas sample The number of hydrogen atoms that can be reduced is reduced. Thereby, at a certain concentration of hydrogen gas in the gas sample, the number of hydrogen atoms that can be adsorbed per unit area at the interface between the catalytic metal layer and the insulating layer, i.e. the number of hydrogen dipoles that can be achieved, is reduced. The This means that the sensitivity is weakened at that time.

  Most gas samples analyzed in connection with hydrogen gas contain air or oxygen gas. For this reason, the aforementioned reduction in the sensitivity of hydrogen gas sensitive semiconductor sensors operating on the hydrogen dipole transducer principle often occurs.

  In addition, there are also other contaminants that adsorb or bind to the outer surface of the catalytic metal layer and can affect sensitivity in the same way as oxygen. An example of such a contaminant is carbon oxide, which is also present in many gas samples. Furthermore, hydrogen sulfide can bind to the outer surface of the catalytic metal layer.

  When utilizing a hydrogen gas sensitive semiconductor sensor operating on the hydrogen dipole transducer principle under such detection conditions where oxygen and / or other contaminants may be adsorbed or bound to the outer surface, the sensor The sensitivity of the sensor typically decays as the sensor ages due to oxidation or contamination by other contaminants on the exterior surface. Normally, the lifetime of a hydrogen gas sensitive semiconductor sensor operating on the hydrogen dipole transducer principle is substantially reduced under such detection conditions.

  One way to prevent loss of sensitivity due to oxygen and other contaminants is to purify the gas sample that the sensor tests from oxygen and other contaminants. And any effect on sensitivity due to oxygen and other contaminants is substantially prevented and the lifetime of the sensor is improved. However, such purification is relatively difficult and complicated to carry out, and if so, extra sample preparation steps are added to the analysis procedure, resulting in a longer total analysis time.

  Another method for preventing sensitivity loss due to oxygen and other contaminants is described in US Pat. According to the method described in Patent Document 2, the semiconductor sensor is exposed to the gas sample during the detection period. Each detection period precedes a period in which the semiconductor sensor is held in an ambient pretreatment gas atmosphere containing negligible amounts of oxygen, hydrogen, and carbon monoxide. The pretreatment period is much longer than the detection period. As a result of the pretreatment period, substantially all oxygen and carbon monoxide, if any, adsorbed on the outer surface of the catalytic metal layer during the preceding detection period is removed. And the above-mentioned effects on sensitivity due to oxygen and other contaminants are substantially prevented and the lifetime of the sensor is improved. However, this method requires the use of equipment for changing the atmosphere surrounding the semiconductor sensor.

  Thus, the two methods described above that prevent sensitivity loss due to oxygen and other contaminants can be used to improve the lifetime of hydrogen gas sensitive semiconductor sensors that operate on the hydrogen dipole transducer principle. However, these two methods do not improve the initial sensitivity of such sensors. Not only is the lifetime of the hydrogen gas sensitive semiconductor sensor operating on the hydrogen dipole transducer principle as long as possible, but the initial sensitivity as high as possible is preferred or required for most applications. As used herein, the term “initial sensitivity” refers to the sensitivity of a sensor in the initial period during initial use of the sensor, ie, the sensitivity of a “new” sensor that has not been previously used.

  Improved initial sensitivity as well as improved lifetime of hydrogen gas sensitive semiconductor sensors operating on the hydrogen dipole transducer principle may, of course, be achieved by modifying the catalytic properties of the catalytic metal layer. One way to modify the catalytic properties of the catalytic metal layer in a hydrogen gas sensitive semiconductor sensor operating on the hydrogen dipole principle to improve the initial sensitivity as well as the lifetime is another way to give the sensor a higher initial sensitivity. This is to use the catalytic metal. However, in most such sensors, catalytic metals are already used today that are known to give the highest initial sensitivity to hydrogen gas sensitive semiconductor sensors. Another way to modify the catalytic properties of the catalytic metal layer in a hydrogen gas sensitive semiconductor sensor operating on the hydrogen dipole transducer principle to improve initial sensitivity as well as lifetime is the temperature of the outer surface during hydrogen gas detection. Is to raise. It is known that when the temperature rises above 150 ° C., the sensitivity to hydrogen gas is improved. However, when the temperature rises above 150 ° C., the selectivity for hydrogen gas is reduced and then the sensitivity to other gaseous hydrogen-containing molecules such as those described above is improved.

Swedish Patent No. 387444 US Pat. No. 6,484,563 Lundstroem, I., Sensors and Actuators 1, 403 (1981) Ackelid, U., et al., Metal-Oxide-Semiconductor structures with thermally activated sensitivity to ethanol vapor and unsaturated hydrocarbons, Proc. 2nd Int. Meet. , Chemical Sensors, Bordeaux 1986, pp 395-398

  There is still a need for a reliable method for improving the initial sensitivity to hydrogen gas molecules, as well as the lifetime of hydrogen gas sensitive semiconductor sensors operating on the hydrogen dipole transducer principle.

  It is an object of the present invention to provide a hydrogen gas sensing semiconductor sensor with improved initial sensitivity to hydrogen gas molecules as well as improved lifetime, which includes a catalytic metal layer, a semiconductor layer, and a catalyst. An insulating layer disposed between the metal layer and the semiconductor layer is included, and the catalytic metal layer includes an outer surface and an inner surface, and the outer surface is configured to freely communicate with an ambient atmosphere. .

  This object is achieved in accordance with the characterizing part of claim 1.

  The inner surface includes at least one hydrogen atom adsorption surface portion, and each hydrogen atom adsorption surface portion is disposed adjacent to the insulating layer, and the surface area of the outer surface is at least one hydrogen atom of the inner surface. Thanks to being at least 100% larger than the total surface area of all adsorbing surfaces, it is possible to realize a hydrogen gas sensitive semiconductor sensor with improved initial sensitivity to hydrogen gas molecules as well as improved lifetime.

  A further object of the present invention is to provide a hydrogen gas detection probe including a hydrogen gas sensing semiconductor sensor with improved initial sensitivity to hydrogen gas molecules as well as improved lifespan. A metal layer, a semiconductor layer, and an insulating layer disposed between the catalytic metal layer and the semiconductor layer are included, and the catalytic metal layer includes an outer surface and an inner surface, and the outer surface is in free communication with the ambient atmosphere. It is configured as follows.

  This object is achieved in accordance with the characterizing part of claim 15.

  The probe includes a hydrogen gas sensing semiconductor sensor, wherein the inner surface includes at least one hydrogen atom adsorption surface portion, and each hydrogen atom adsorption surface portion is disposed adjacent to the insulating layer, And in this semiconductor sensor, the surface area of the outer surface is at least 100% larger than the total surface area of all of the at least one hydrogen atom adsorption surface part of the inner surface, so that the initial sensitivity to hydrogen gas molecules is improved as well as the improvement of the lifetime. It is possible to realize a probe including a hydrogen gas sensing semiconductor sensor.

  Another object of the present invention is to provide a hydrogen gas detection system including a probe and a measurement unit. This probe includes a hydrogen gas with improved initial sensitivity to hydrogen gas molecules as well as improved life. A sensing semiconductor sensor is included that includes a catalytic metal layer, a semiconductor layer, and an insulating layer disposed between the catalytic metal layer and the semiconductor layer, and the catalytic metal layer includes an outer surface and an inner surface. And the outer surface is configured to communicate freely with the surrounding atmosphere.

  This object is achieved according to the characterizing part of claim 16.

  The hydrogen gas detection system includes a probe including a hydrogen gas sensing semiconductor sensor, wherein the inner surface includes at least one hydrogen atom adsorption surface portion, and each hydrogen atom adsorption surface portion is an insulating layer. Gas detection system comprising a probe and a measurement unit, arranged adjacent to each other and in this semiconductor sensor, the surface area of the outer surface being at least 100% greater than the total surface area of all at least one hydrogen atom adsorption surface portion of the inner surface And the probe can include a hydrogen gas sensitive semiconductor sensor with improved initial sensitivity to hydrogen gas molecules as well as increased lifetime.

  Preferred embodiments are listed in the dependent claims.

  Further objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It should be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the scope of the invention, and reference should be made to the appended claims for the scope of the invention. That the drawings are not necessarily drawn to scale, and that unless otherwise indicated, the drawings are only intended to conceptually illustrate the structures described herein; Please understand further.

  In the drawings, like reference characters indicate like elements throughout the several views.

  FIG. 1 is a schematic cross-sectional view of the basic structure and basic operating principle of a prior art gas sensing semiconductor sensor, which operates based on the hydrogen dipole transducer principle and is used for detection of hydrogen gas it can. Most prior art hydrogen gas sensitive semiconductor sensors that operate on the hydrogen dipole transducer principle include or are constructed based on the basic structure shown in FIG. For example, it represents the basic structure of the semiconductor sensor of SE387444. A prior art hydrogen gas sensing semiconductor sensor operating on the hydrogen dipole transducer principle includes a catalytic metal layer 1, a semiconductor layer 2, and an insulating layer 3 disposed between the catalytic metal layer 1 and the semiconductor layer 2. included. The catalytic metal layer 1 includes an outer surface 4 configured to be in physical contact with and freely communicate with the ambient atmosphere, ie, the atmosphere surrounding the sensor or the atmosphere surrounding the catalytic metal layer 1. Therefore, the outer surface 4 defines the boundary of the catalytic metal layer 1 with respect to the ambient atmosphere, and is configured to adsorb hydrogen gas molecules from the ambient atmosphere and dissociate the adsorbed hydrogen gas molecules. The outer surface 4 includes all surface portions of the catalytic metal layer 1 configured to be in physical contact with the ambient atmosphere and to be in free communication.

  Furthermore, the catalytic metal layer 1 has a top surface 5 and a side surface 6 where the terms “top” and “side” refer to the positions of the surface 5 and the surface 6 when the basic structure of the semiconductor sensor has the orientation shown in FIG. Are used to indicate each. Therefore, when the basic structure of the semiconductor sensor has the orientation shown in FIG. 1, the side surface 6 is the surface of the catalytic metal layer 1 that defines the boundary of the catalytic metal layer 1 in the horizontal direction. The catalytic metal layer 1 includes side surfaces 6 so that the catalytic metal layer 1 has a certain thickness. In a prior art hydrogen gas sensing semiconductor sensor operating on the hydrogen dipole transducer principle, the entire top surface 5 and the entire side surface 6 are configured to be in physical contact with the ambient atmosphere and in free communication. . Accordingly, the outer surface 4 includes all the surface portions of the catalytic metal layer 1 configured to be in physical contact with and freely communicate with the surrounding atmosphere, and therefore the outer surface 4 includes the entire upper surface 5. Similarly, the entire side surface 6 is also included.

  Further, the catalytic metal layer 1 includes an inner surface 7, but the inner surface 7 is not in physical contact with the surrounding atmosphere and is configured not to communicate freely. That is, the inner surface 7 cannot adsorb hydrogen gas molecules from the ambient atmosphere. In the known hydrogen gas sensing semiconductor sensor operating on the hydrogen dipole transducer principle and having the basic structure shown in FIG. 1, the surface area of the upper surface 5 is substantially equal to the surface area of the inner surface 7. However, despite the fact that the outer surface 4 includes side surfaces 6 as well as the upper surface 5, the surface area of the outer surface 4 is also substantially equal to the surface area of the inner surface 7. This is because the catalytic metal layer 1 is very thin, and therefore the surface area of the side surface 6 is very small compared to the surface area of the upper surface 5. Usually, the catalytic metal layer 1 is produced by thin film technology.

  The inner surface 7 of the prior art sensor includes a hydrogen atom adsorption surface portion 8 that leans against or is at least adjacent to the insulating layer 3. That is, there are no further components between the hydrogen atom adsorption surface portion 8 and the insulating layer 3. In the present specification, the term “hydrogen atom adsorption surface portion” refers to a surface portion that leans against the insulating layer 3 or is disposed at least adjacent thereto. Hydrogen atoms can be adsorbed on the hydrogen atom adsorption surface portion 8. Or, more specifically, hydrogen atoms can be adsorbed at the adsorption sites of hydrogen atoms at the interface between the hydrogen atom adsorption surface portion 8 and the insulating layer 3.

  In the prior art sensor, the hydrogen atom adsorption surface 8 constitutes about 55% of the inner surface 7. Accordingly, about 55% of the inner surface 7 rests on or is at least adjacent to the insulating layer 3. The remaining surface portion (s) of the inner surface 7, i.e., about 45% of the inner surface 7, is disposed adjacent to a contact frame or the like (not shown). Therefore, since the surface areas of the outer surface 4 and the inner surface 7 are substantially equal, the surface area of the outer surface 4 in the prior art sensor is approximately 80% larger than the surface area of the hydrogen atom adsorption surface portion 8.

  For illustration, in FIG. 1, hydrogen gas molecules are indicated by HH and hydrogen atoms are indicated by H.

  The basic operating principle of the hydrogen gas sensing semiconductor sensor having the basic structure shown in FIG. 1 will now be described. When hydrogen gas molecules are present in an atmosphere surrounding the hydrogen gas sensing semiconductor sensor having the basic structure shown in FIG. 1, some hydrogen gas molecules can be adsorbed on the outer surface 4 of the catalytic metal layer 1. Next, the adsorbed hydrogen gas molecules are dissociated at the outer surface 4, and the hydrogen atoms thus formed can be absorbed by the catalyst metal layer 1. Subsequently, after some of the absorbed hydrogen atoms diffuse through the catalytic metal layer 1, the interface between the catalytic metal layer 1 and the insulating layer 3, that is, the hydrogen atom adsorption surface portion of the inner surface 7 in the catalytic metal layer 1. 8 is adsorbed.

  Hydrogen atoms adsorbed at the interface between the catalytic metal layer 1 and the insulating layer 3, that is, the hydrogen atom adsorption surface portion 8 of the inner surface 7, are polarized, and a hydrogen dipole is generated. This is shown schematically in FIG. The hydrogen dipole generates an electric field that shifts the effective work function of the catalytic metal layer 1. As a result of the shift of the effective work function of the catalytic metal layer 1, the electrical function of the semiconductor sensor is affected. That is, a voltage shift in the characteristics of the semiconductor sensor is generated and this effect can be used for detecting the presence of hydrogen gas molecules and / or measuring the concentration of hydrogen gas molecules in the gas sample. The magnitude of the shift is the number of hydrogen atoms adsorbed per unit area, that is, the hydrogen dipole at the hydrogen atom adsorption surface 8 or more specifically at the interface between the hydrogen atom adsorption surface 8 and the insulating layer 3. It is determined by the density of.

  Since the amount of hydrogen gas molecules in the atmosphere surrounding the sensor and the density of the hydrogen dipole in the hydrogen atom adsorption surface portion 8 are balanced after a certain time, the sensor uses the equilibrium shift of the effective work function of the catalytic metal layer 1 to The concentration of hydrogen gas molecules in the surrounding atmosphere, that is, the gas sample can be measured. However, the time until equilibrium is achieved between the amount of hydrogen gas molecules in the atmosphere surrounding the sensor and the density of hydrogen dipoles at the hydrogen atom adsorption surface 8 is usually relatively long. For that reason, the rate at which the effective work function shifts, i.e. the rate at which the output signal shifts before the equilibrium shift is achieved, is preferably used to measure the concentration of hydrogen gas molecules in the atmosphere surrounding the sensor, i.e. the gas sample. .

  Prior art hydrogen gas sensitive semiconductor sensors operating on the hydrogen dipole transducer principle are usually implemented as field effect transistors. Next, hydrogen atoms can be adsorbed on the entire hydrogen atom adsorption surface portion 8 of the inner surface 7 in the catalyst metal layer 1, but only hydrogen atoms adsorbed on the portion of the hydrogen atom adsorption surface portion 8 arranged in the channel. Affects the voltage shift in the sensor characteristics. This is described further below.

  3-6 show the basic structure of different embodiments of a hydrogen gas sensitive semiconductor sensor according to the present invention operating on the hydrogen dipole transducer principle. The hydrogen gas sensitive semiconductor sensor according to the present invention includes, in all embodiments, a catalytic metal layer 1, a semiconductor layer 2, and an insulating layer 3 disposed between the catalytic metal layer 1 and the semiconductor layer 2. The catalytic metal layer 1 includes an outer surface 4 configured to be in physical contact with and freely communicate with the ambient atmosphere, ie, the atmosphere surrounding the sensor or the atmosphere surrounding the catalytic metal layer 1. Therefore, the outer surface 4 defines the boundary of the catalytic metal layer 1 with respect to the ambient atmosphere, and is configured to adsorb hydrogen gas molecules from the ambient atmosphere and dissociate the adsorbed hydrogen gas molecules. The outer surface 4 includes all surface portions of the catalytic metal layer 1 configured to be in physical contact with the ambient atmosphere and to be in free communication.

  The term “catalytic metal” is used herein to denote a metal or alloy that can dissociate hydrogen gas molecules and absorb the hydrogen atoms thus formed. According to this definition, non-limiting examples of catalytic metals in the catalytic metal layer 1 of the sensor according to the invention are either the platinum metals palladium, platinum and iridium, or an alloy comprising at least one of these metals. is there. Non-limiting examples of alloys that can constitute the catalytic metal are alloys containing silver and palladium, or alloys containing nickel and palladium.

  The catalytic metal layer 1 of the sensor according to the invention has a top surface 5 and a side surface 6, where the terms “top” or “side” refer to the surface 5 and the surface when the basic structure of the sensor has the orientation shown in FIGS. Used to indicate the position of surface 6 respectively. Preferably, the outer surface 4 of the sensor according to the invention includes both the entire top surface 5 and the entire side surface 6. However, the side surface 6 is completely or partially covered by some other component (s) of the sensor in a variant so that it is completely or partially restricted from freely communicating with the ambient atmosphere. May be. Thus, the outer surface 4 includes the upper surface 5 and the portion (s) of the side surface 6 configured to communicate freely with the surrounding atmosphere, if any.

  Further, the catalytic metal layer 1 includes an inner surface 7, but the inner surface 7 is not in physical contact with the surrounding atmosphere and is configured not to communicate freely. That is, the inner surface 7 cannot adsorb hydrogen gas molecules from the ambient atmosphere. In the sensor according to the present invention, the inner surface 7 includes at least one hydrogen atom adsorption surface portion 8. Each hydrogen atom adsorption surface portion 8 is arranged so as to be adjacent to or lean against the insulating layer 3. That is, there are no further components between the hydrogen atom adsorption surface portion 8 and the insulating layer 3. Accordingly, in the sensor according to the present invention, the inner surface 7 can include one hydrogen atom adsorption surface portion 8 (FIGS. 3 to 4 and 6) or more than one hydrogen atom adsorption surface portion 8 (FIG. 5). The inner surface 7 of the prior art hydrogen gas sensing semiconductor sensor operating on the hydrogen dipole transducer principle includes only one hydrogen atom adsorption surface 8 (FIG. 1). Furthermore, as in the prior art sensors, the inner surface 7 of the sensor according to the invention also includes one or several surface portions arranged adjacent to a contact frame or the like (not shown). For example, the total surface area of the surface portion (s) disposed adjacent to the contact frame or the like may constitute about 45% of the surface area of the inner surface 7, as in prior art sensors. However, the percentage that the total surface area of the surface portion (s) arranged adjacent to the contact frame or the like constitutes the surface area of the inner surface 7 may be changed.

  Further, in the sensor according to the present invention, the ratio of the surface area of the outer surface 4 to the total surface area of all the hydrogen atom adsorption surface portions 8 on the inner surface 7 is based on the hydrogen dipole transducer principle. Compared to semiconductor sensors, there is a substantial increase. In the prior art sensor, the surface area of the outer surface 4 is about 80% larger than the total surface area of all hydrogen atom adsorption surface portions 8, ie, one hydrogen atom adsorption surface portion 8, as described above.

  The fact that the ratio of the surface area of the outer surface 4 to the total surface area of all hydrogen atom adsorption surface portions 8 of the inner surface 7 is substantially increased in the sensor according to the invention compared to its ratio in the prior art sensor. Means the following: That is, the number of locations configured to adsorb and dissociate hydrogen gas molecules on the outer surface 4 relative to the total number of locations configured to adsorb hydrogen atoms on the hydrogen atom adsorption surface portion (s) 8 of the inner surface 7. This ratio is substantially increased in the sensor according to the invention compared to that in prior art sensors.

  And the sensor according to the present invention is substantially adsorbed per unit area at the hydrogen atom adsorption surface part (s) 8 of the inner surface 7 at a certain concentration of hydrogen gas in the gas sample, compared to the prior art prior art sensor. A higher number of hydrogen atoms, i.e. higher density dipoles. Thus, a sensor according to the present invention has a substantially higher initial sensitivity than prior art sensors, and a hydrogen gas sensitive semiconductor sensor with a substantially improved initial sensitivity is provided according to the present invention.

  As described above, the sensitivity of a hydrogen gas sensitive semiconductor sensor operating on the hydrogen dipole transducer principle is such that the sensor is adsorbed or bound to the outer surface 4 of the catalytic metal layer 1 due to oxygen and / or other contaminants. It typically fades with age. Thereby, the lifetime of a hydrogen gas sensitive semiconductor sensor operating on the hydrogen dipole transducer principle is substantially reduced due to adsorption or binding of oxygen and / or other contaminants to the outer surface 4 of the catalytic metal layer 1. To do.

  However, the fact that the initial sensitivity of the sensor according to the invention is substantially improved compared to the initial sensitivity of the prior art sensor is also that the lifetime of the sensor according to the invention is compared to the lifetime of the prior art sensor. Means substantially improved. This fact should be apparent to those skilled in the art. Constructed to adsorb and dissociate hydrogen gas molecules on the outer surface 4 relative to the total number of locations configured to adsorb hydrogen atoms on the hydrogen atom adsorption surface portion (s) 8 of the inner surface 7 of the sensor according to the present invention. A substantial increase in the ratio of the number of points means the following. That is, the more sensitive the sensor is no longer usable, the longer it takes for oxygen and / or other contaminants to occupy so many locations on the outer surface 4. And the lifetime of the sensor according to the present invention is substantially improved compared to the lifetime of prior art sensors.

  Thus, according to the present invention, the above means for improving the lifetime of a hydrogen gas sensitive semiconductor sensor, namely the purification of a gas sample from oxygen and other contaminants, the change of the ambient atmosphere surrounding the semiconductor sensor or the catalytic metal None of the use of equipment for changing the catalytic properties of the bed is necessary to obtain an improved lifetime of a hydrogen gas sensitive semiconductor sensor operating on the hydrogen dipole transducer principle. However, further improvements in life can be achieved when the sensor according to the invention is combined with any such means.

  Depending on the application of the sensor according to the invention, the benefits of the sensor can be an increase in initial sensitivity, an increase in lifetime or a combination of both.

  Furthermore, prior art sensors and sensors according to the present invention reduce the sensitivity of any of those sensors to a degree after a period of use but to the extent that oxygen and / or other contaminants are no longer usable. Before comparison, hydrogen gas molecules are still freely adsorbed and dissociated on the outer surface 4 with respect to the total number of locations configured to adsorb hydrogen atoms on the hydrogen atom adsorption surface part (s) 8. The ratio of the number of points is substantially higher with the sensor according to the invention than in the prior art sensor. And after a period of use, but before oxygen and / or other contaminants reduce the sensitivity of any of those sensors to the extent that the sensor is no longer usable, the sensor according to the present invention At a certain concentration of hydrogen gas in the sample, it can provide a substantially higher dipole density at the hydrogen atom adsorption surface (s) 8 of the inner surface 7 than prior art sensors. Thus, if the sensors are compared after a period of use, but before the sensitivity of any of those sensors drops to the extent that the sensor is no longer usable, the sensor according to the present invention Has substantially higher sensitivity than prior art sensors.

  Furthermore, the initial sensitivity is adjusted to achieve the desired initial sensitivity by changing the ratio of the surface area of the outer surface 4 to the total surface area of all hydrogen atom adsorption surface portions 8 on the inner surface 7 of the sensor according to the invention. May be.

  It is according to the invention that the ratio of the surface area of the outer surface 4 to the total surface area of all hydrogen atom adsorption surface portions 8 on the inner surface 7 of the sensor according to the invention is increased compared to that ratio in the prior art sensor. This means that the manufacturing cost of the sensor increases. This will become clear below. In order to achieve a sufficiently large effect that is intriguing even in view of the increased manufacturing costs, i.e. an improvement in the initial sensitivity, the surface area of the outer surface 4 is determined by adsorption of at least one hydrogen atom on the inner surface 7 of the sensor according to the invention. It must be at least 100% larger than the total surface area of the entire surface 8. Therefore, in the hydrogen gas sensing semiconductor sensor according to the present invention, the surface area of the outer surface 4 is at least 100% larger than the total surface area of the entire at least one hydrogen atom adsorption surface portion 8 on the inner surface 7.

  Furthermore, the greater the increase, the higher the initial sensitivity. However, as the increase increases, manufacturing costs typically increase. When the ratio of the surface area of the outer surface 4 to the total surface area of the entire at least one hydrogen atom adsorption surface portion 8 is selected, the advantages of improving the initial sensitivity and the increase in manufacturing cost must be compared with each other. I must. Depending on the application, it may be preferable or necessary to give the sensor a very high initial sensitivity in order to be able to measure very low concentrations of hydrogen gas molecules in the gas sample. If so, for example, the surface area of the outer surface 4 may be preferably at least 500% greater than the total surface area of the entire at least one hydrogen atom adsorption surface portion 8 of the inner surface 7. For other applications, it is preferred or necessary to give the sensor an extremely high initial sensitivity so that extremely low concentrations of hydrogen gas molecules in the gas sample can be measured. If so, for example, the surface area of the outer surface 4 may be preferably at least 5000% greater than the total surface area of the entire at least one hydrogen atom adsorption surface portion 8 of the inner surface 7.

  FIG. 3 shows a schematic cross-sectional view of the basic structure in the first embodiment of the sensor according to the present invention. In the first embodiment, the inner surface 7 includes one hydrogen atom adsorption surface portion 8, which surface portion 8 leans against the insulating layer 3 or is disposed at least adjacently. That is, there are no further components between the hydrogen atom adsorption surface portion 8 and the insulating layer 3. As described above, in this specification, the term “hydrogen atom adsorption surface portion” refers to a surface portion that leans against the insulating layer 3 or is disposed at least adjacent thereto. Hydrogen atoms can be adsorbed on the hydrogen atom adsorption surface portion 8. Or, more specifically, hydrogen atoms can be adsorbed at the adsorption sites of hydrogen atoms at the interface between the hydrogen atom adsorption surface portion 8 and the insulating layer 3.

  Furthermore, the surface expansion structure 10 is provided on the upper surface 5 of the first embodiment. The structure 10 has a ratio of the surface area of the outer surface 4 to the surface area of the hydrogen atom adsorption surface portion 8 on the inner surface 7 leading. It is configured to mean that it increases substantially compared to its ratio in the sensor of the technology. More specifically, the applied surface extension structure 10 is adjusted to mean that the surface area of the outer surface 4 is at least 100% greater than the surface area of the hydrogen atom adsorption surface portion 8 of the inner surface 7. Depending on the application, the applied surface extension structure 10 is adjusted to mean that the surface area of the outer surface 4 is at least 500% larger than the surface area of the hydrogen atom adsorption surface portion 8 of the inner surface 7 for other applications. On the other hand, the surface area of the outer surface 4 is adjusted to be at least 5000% larger than the surface area of the hydrogen atom adsorption surface portion 8 of the inner surface 7.

  The particular structure of the surface extension structure 10 shown in FIG. 3 is merely one example of a possible structure of the surface extension structure 10 that can be applied to the upper surface 5 to geometrically expand the outer surface 4. Accordingly, in a variation of the first embodiment, the surface extension structure 10 has a different specific structure, and a structure different from the structure shown in FIG. For example, the surface extension structure 10 may be corrugated. The surface extension structure 10 may also be irregular.

  The surface extension structure 10 may be applied to the upper surface 5 by, for example, photolithography, whereby a pattern is first defined by photographic techniques and then created by etching or sputtering / blasting.

  Another way (not shown) for applying the surface extension structure 10 to the top surface 5 is to design the sensor such that the catalytic metal layer 1 is porous in the top partial layer (s), The term “top” is used to indicate the position of the mentioned partial layer (s) in the catalytic metal layer 1 when the basic structure of the sensor according to the invention has the orientation shown in FIG. Next, the porosity of the uppermost partial layer (s) means that the upper surface 5 is provided with the surface expansion structure 10. The porosity of the top partial layer (s) can be achieved, for example, by etching, plating or vapor deposition.

  The sensor according to the first embodiment of the invention and the sensor according to the first embodiment of the present invention has a surface area of the outer surface 4 of the sensor according to the first embodiment of the present invention. Comparing these sensors, only differing in that they are substantially larger than the area, the sensor according to the first embodiment of the present invention is due to the adsorption and dissociation of hydrogen gas molecules compared to the prior art sensors. There are substantially more locations configured. Thereby, at a certain concentration of hydrogen gas molecules in the gas sample, a substantially larger number of hydrogen gas molecules are adsorbed and dissociated by the sensor according to the first embodiment of the invention than the prior art sensor in initial use. Can be done. This means the following. That is, at a certain concentration of hydrogen gas molecules in a gas sample, in the sensor according to the first embodiment of the present invention in the initial use, the hydrogen atom adsorption surface is substantially more That is, it can be adsorbed for each unit area of the portion 8. As a result, the initial sensitivity of the sensor according to the first embodiment of the present invention is substantially higher than the initial sensitivity of prior art sensors. Next, according to the above, the lifetime of the sensor according to the first embodiment of the present invention is also substantially longer than the lifetime of the prior art sensor. Furthermore, the sensor according to the first embodiment of the present invention not only has a substantially higher sensitivity initially than prior art sensors. Prior art sensors and sensors according to the first embodiment of the present invention have reduced the sensitivity of any of the sensors by oxygen and other contaminants to some extent after a period of use but the sensor is no longer usable. Before being compared, the sensor according to the first embodiment of the present invention still has a substantially higher sensitivity than the prior art sensor.

  4a and 4b show a schematic cross-sectional view and a schematic perspective view, respectively, of the basic structure in a second embodiment of the sensor according to the invention. In the second embodiment, the upper surface 5 does not include the surface expansion structure 10 unlike the upper surface 5 of the first embodiment. Furthermore, the surface areas of the inner surface 7 and the outer surface 4 are substantially equal. In the second embodiment, the inner surface 7 includes one hydrogen atom adsorption surface portion 8 that is disposed against or adjacent to the insulating layer 3. Further, the inner surface 7 includes a hydrogen atom adsorption suppressing surface portion 9 that is not disposed so as to lean against or be adjacent to the insulating layer 3.

  In the present specification, the term “hydrogen atom adsorption-suppressing surface portion” refers to a surface portion that is not disposed so as to lean against or be adjacent to the insulating layer 3. Hydrogen atoms are not adsorbed or at least substantially not adsorbed on the hydrogen atom adsorption suppressing surface portion 9. The hydrogen atom adsorption suppression surface portion 9 and the insulating layer are arranged so that the entire hydrogen atom adsorption suppression surface portion 9 is placed against or adjacent to the hydrogen atom adsorption suppression material layer 11. 3 between. In this specification, the term “hydrogen atom adsorption-suppressing material” refers to a material that includes little or very few sites for adsorption of hydrogen atoms. The hydrogen atom adsorption suppressing material layer 11 substantially suppresses the adsorption of hydrogen atoms on the hydrogen atom adsorption suppressing surface portion 9, or more specifically, the hydrogen atom adsorption suppressing surface portion 9 and the hydrogen atom adsorption suppressing material layer. 11 substantially suppresses the adsorption of hydrogen atoms at the interface between the two. Accordingly, the hydrogen atoms cannot be adsorbed at all or substantially at the hydrogen atom adsorption suppressing surface portion 9, or more specifically, the hydrogen atoms are separated from the hydrogen atom adsorption suppressing surface portion 9 and the hydrogen atom. It cannot be adsorbed at all or substantially at the interface with the adsorption suppressing material layer 11. Even in the case where the adsorption of hydrogen atoms on the hydrogen atom adsorption suppressing surface portion 9 is not completely suppressed, that is, when the hydrogen atom adsorption suppressing surface portion 9 can be adsorbed on the hydrogen atom adsorption suppressing surface portion 9 only. Even if it exists, it is suppressed compared with adsorption | suction of the hydrogen atom in the hydrogen atom adsorption | suction surface part 8. FIG. Thereby, even if a small number of hydrogen atoms can be adsorbed on the hydrogen atom adsorption-suppressing surface portion 9, it is indicated in the present specification that the adsorption of hydrogen atoms is suppressed.

  The hydrogen atom adsorption suppressing material is preferably a non-catalytic metal or a non-catalytic alloy. For example, the hydrogen atom adsorption suppressing material is aluminum, an aluminum alloy, or chromium. The thickness of the hydrogen atom adsorption suppressing material layer 11 is 0.001 to 0.3 μm.

  The surface area of the hydrogen atom adsorption suppressing surface portion 9 in the second embodiment of the sensor according to the present invention is adjusted as follows. That is, it is adjusted to mean that the ratio of the surface area of the outer surface 4 to the surface area of the hydrogen atom adsorption surface portion 8 is substantially increased compared to that ratio in prior art sensors. More specifically, the surface area of the hydrogen atom adsorption suppressing surface portion 9 is adjusted as follows. That is, it is adjusted to mean that the surface area of the outer surface 4 is at least 100% greater than the surface area of the hydrogen atom adsorption surface portion 8 of the inner surface 7. Depending on the application, it is adjusted so that the surface area of the outer surface 4 is at least 500% larger than the surface area of the hydrogen atom adsorption surface 8 of the inner surface 7, and for other applications the surface area of the outer surface 4 is the inner surface. 7 is adjusted to be at least 5000% larger than the surface area of the hydrogen atom adsorption surface portion 8. The surface area of the hydrogen atom adsorption suppression surface portion 9 is adjusted by adjusting the surface area of the hydrogen atom adsorption suppression material layer 11 on which the hydrogen atom adsorption suppression surface portion 9 stands or is disposed adjacently.

  The prior art sensor and the sensor according to the second embodiment of the present invention differ only in that the inner surface 7 of the sensor according to the present invention includes a hydrogen atom adsorption suppression surface portion 9 (that is, each sensor has one hydrogen These sensors have, for example, an atomic adsorption surface 8 and have, for example, an equal surface area of the inner surface 7, an equal surface area of the outer surface 4, and an equal percentage of the inner surface 7 arranged adjacent to the contact frame or the like. When comparing these sensors, the hydrogen atom adsorption surface 8 of the sensor according to the second embodiment of the present invention is substantially smaller than the hydrogen atom adsorption surface 8 of the prior art sensor. Therefore, the sensor according to the second embodiment of the present invention has a location for adsorbing hydrogen atoms on the surface area of the inner surface 7 which is substantially smaller than the sensor of the prior art. And even the prior art sensor and the sensor according to the second embodiment of the invention have an equal surface area of the outer surface 4 and thus an equal number of locations configured for the adsorption and dissociation of hydrogen gas molecules Nevertheless, at a certain concentration of hydrogen gas in the gas sample, a substantially higher density of hydrogen dipoles can be achieved in the sensor according to the second embodiment of the invention than in prior art sensors. As a result, the initial sensitivity of the sensor according to the second embodiment of the present invention is substantially higher than the initial sensitivity of the prior art sensor. According to the above, furthermore, the lifetime of the sensor according to the second embodiment of the present invention is substantially longer than the lifetime of the prior art sensor. Furthermore, the sensor according to the second embodiment of the invention not only initially has a substantially higher sensitivity than prior art sensors. Prior art sensors and sensors according to the first embodiment of the present invention have reduced the sensitivity of any of the sensors by oxygen and other contaminants to some extent after a period of use but the sensor is no longer usable. The sensor according to the second embodiment of the present invention still has a substantially higher sensitivity than prior art sensors when compared before.

  In the first and second embodiments of the sensor according to the present invention, the inner surface 7 includes one hydrogen atom adsorption surface 8. However, in other embodiments, as described above, the inner surface 7 may include more than one hydrogen atom adsorption surface portion.

  FIG. 5 shows a schematic perspective view of the basic structure in a third embodiment of the sensor according to the invention, in which the inner surface 7 has three hydrogen atoms which are either leaning against or adjacent to the insulating layer 3. An adsorption surface portion 8 and one hydrogen atom adsorption suppression surface portion 9 which is disposed against or adjacent to the hydrogen atom adsorption suppression material layer 11 are included. In the third embodiment, the upper surface 5 does not include the surface expansion structure 10. Furthermore, the surface areas of the inner surface 7 and the outer surface 4 are substantially equal.

  In the third embodiment, the surface area of the hydrogen atom adsorption suppressing surface portion 9 is adjusted as follows. That is, the ratio of the surface area of the outer surface 4 to the total surface area of all the hydrogen atom adsorption surface portions 8, that is, the three hydrogen atom adsorption surface portions 8, is substantially compared to that ratio in the prior art sensor. Adjusted to mean increasing. More specifically, the surface area of the hydrogen atom adsorption suppressing surface portion 9 is adjusted as follows. That is, it is adjusted to mean that the surface area of the outer surface 4 is at least 100% greater than the total surface area of the three hydrogen atom adsorption surface portions 8 of the inner surface 7. Depending on the application, it is adjusted so that the surface area of the outer surface 4 is at least 500% larger than the total surface area of the three hydrogen atom adsorption surface portions 8 of the inner surface 7, and for other applications it is The surface area is adjusted to be at least 5000% larger than the total surface area of the three hydrogen atom adsorption surface portions 8 of the inner surface 7. The surface area of the hydrogen atom adsorption suppression surface portion 9 is adjusted by adjusting the surface area of the hydrogen atom adsorption suppression material layer 11 on which the hydrogen atom adsorption suppression surface portion 9 stands or is disposed adjacently.

  In a modification (not shown) of the third embodiment, the inner surface 7 includes a different number of hydrogen atom adsorption surface portions 8 from the third embodiment. The inner surface 7 may include any suitable number of hydrogen atom adsorption surface portions 8 in such deformation.

  FIG. 6 shows a schematic cross-sectional view of a basic structure in a fourth embodiment of a sensor according to the invention, which is a combination of the first and second embodiments. In the fourth embodiment, the inner surface 7 of the sensor leans against or is adjacent to one hydrogen atom adsorption surface portion 8 disposed against or adjacent to the insulating layer 3 and the hydrogen atom adsorption suppression material layer 11. One hydrogen atom adsorption suppressing surface portion 9 arranged in the manner described above is included. Furthermore, the upper surface 5 is provided with a surface expansion structure 10.

  The surface extension structure 10 and the surface area of the hydrogen atom adsorption suppressing surface portion 9 are adjusted as follows. That is, they are adjusted to mean that the ratio of the surface area of the outer surface 4 to the surface area of the hydrogen atom adsorption surface portion 8 is substantially increased compared to that ratio in prior art sensors. . More specifically, the surface area of the provided surface extension structure 10 and the hydrogen atom adsorption suppression surface portion 9 is adjusted as follows. That is, they are adjusted to mean that the surface area of the outer surface 4 is at least 100% greater than the surface area of the hydrogen atom adsorption surface portion 8 of the inner surface 7. Depending on the application, they are adjusted such that the surface area of the outer surface 4 is at least 500% larger than the surface area of the hydrogen atom adsorption surface 8 of the inner surface 7, and for other applications they are the surface of the outer surface 4 The area is adjusted to be at least 5000% larger than the surface area of the hydrogen atom adsorption surface portion 8 of the inner surface 7.

  In a modification (not shown) of the fourth embodiment, the inner surface 7 includes a different number of hydrogen atom adsorption surface portions 8 from that of the fourth embodiment. In such a modification, the inner surface 7 may include any appropriate number of hydrogen atom adsorption surface portions 8.

  Furthermore, in the second, third, and fourth embodiments, the inner surface 7 includes one hydrogen atom adsorption suppressing surface portion 9. However, in other embodiments (not shown), the inner surface 7 may include more than one hydrogen atom adsorption suppressing surface portion 9. Next, the hydrogen atom adsorption suppressing material layer 11 is sandwiched between each hydrogen atom adsorption suppressing surface portion 9 and the insulating layer 3. Each hydrogen atom adsorption suppression surface portion 9 is disposed adjacent to the hydrogen atom adsorption suppression material layer 11. When the inner surface 7 includes at least two hydrogen atom adsorption suppressing surface portions 9 and at least two hydrogen atom adsorption suppressing material layers 11 are disposed between the catalytic metal layer 1 and the insulating layer 3 All of the at least two hydrogen atom adsorption inhibiting material layers 11 may be the same hydrogen atom adsorption inhibiting material, or at least two of the hydrogen atom adsorption inhibiting material layers 11 may be different hydrogen atom adsorption inhibiting materials. Further, in the embodiment having more than one hydrogen atom adsorption suppressing surface portion 9, a surface expansion structure 10 may be provided on the upper surface 5. However, in some embodiments having more than one hydrogen atom adsorption inhibiting surface 9, the top surface 5 is not provided with a surface expansion structure 10. Furthermore, embodiments having more than one hydrogen atom adsorption inhibiting surface portion 9 may include any suitable number of hydrogen atom adsorption surface portions 8. However, the sensor according to the invention of course includes at least one hydrogen atom adsorption surface 8.

  Therefore, the sensor according to the present invention may include any appropriate number of hydrogen atom adsorption surface portions 8 and any appropriate number of hydrogen atom adsorption suppression surface portions 9. However, this sensor, of course, contains at least one hydrogen atom adsorption surface 8, whereas this sensor does not contain any hydrogen atom adsorption suppression surface 9, or one or more The hydrogen atom adsorption suppressing surface portion 9 may be included. Furthermore, the sensor according to the present invention comprises any suitable number of hydrogen atom adsorption surface portions 8 in combination with the upper surface 5 provided with the surface expansion structure 10 or in combination with the upper surface 5 not provided with the surface expansion structure 10. Any appropriate number of hydrogen atom adsorption suppressing surfaces 9 may be included.

  The hydrogen gas sensing semiconductor sensor according to the present invention can be used for the detection of hydrogen gas in the atmosphere surrounding the sensor. That is, it can be used for the detection of hydrogen gas in a gas sample or gas volume sample. More specifically, the hydrogen gas sensitive semiconductor sensor according to the present invention can be used for detecting the presence of hydrogen gas molecules in a gas sample and / or measuring the concentration of hydrogen gas molecules in a gas sample.

  The hydrogen gas sensitive semiconductor sensor according to the present invention can be realized, for example, as a metal-insulator-semiconductor field effect device or a Schottky barrier device. Any embodiment of the hydrogen gas sensitive semiconductor sensor according to the present invention can be realized as a metal-insulator-semiconductor field effect device or a Schottky barrier device. It should be apparent to those skilled in the art to realize the hydrogen gas sensitive semiconductor sensor according to the present invention as a metal-insulator-semiconductor field effect device or Schottky barrier device. For example, the hydrogen gas sensing semiconductor sensor according to the present invention can be realized as a field effect transistor. FIGS. 7 and 8 show two examples of sensor implementations according to the invention as field effect transistors, but these two examples include different embodiments of sensors according to the invention. However, according to the foregoing, any embodiment of the sensor according to the present invention other than that shown in FIGS. 7 and 8 may be included in the field effect transistor.

  FIG. 7 is a schematic cross-sectional view of a basic structure of a field effect transistor including the basic structure in the first embodiment of the sensor according to the present invention. The transistor is made of, for example, a p-type silicon semiconductor 12, and two n-type silicon layers 13 are integrated therein. The insulating layer 3 is in contact with the semiconductor layers 12 and 13. The transistor further includes a source electrode 14, a drain electrode 15 and a channel 16. The catalytic metal layer 1 constitutes a gate. When the transistor having the basic structure shown in FIG. 7 is used for detection of hydrogen gas in a gas sample, hydrogen atoms can be adsorbed on the entire hydrogen atom adsorption surface portion 8, but substantially the channel 16 Only the hydrogen atoms adsorbed at the part of the hydrogen atom adsorbing surface 8 on the top affect the voltage shift in the sensor characteristics. This should be apparent to those skilled in the art and will not be further described here. The term “above” in the phrase “substantially the portion of the hydrogen atom adsorption surface portion above the channel” means the position of the portion in the hydrogen atom adsorption surface portion 8 when the basic structure of the transistor has the orientation shown in FIG. Used to indicate

  FIG. 8 is a schematic cross-sectional view of the basic structure of a field effect transistor including the basic structure in the fourth embodiment of the sensor according to the present invention. The basic structure shown in FIG. 8 is different from the basic structure shown in FIG. 7 in that the inner surface 7 further includes a hydrogen atom adsorption suppressing surface portion 9. A hydrogen atom adsorption suppressing material layer 11 is sandwiched between the hydrogen atom adsorption suppressing surface portion 9 and the insulating layer 3. The main portion of the surface portion of the inner surface 7 substantially above the two silicon layers 13 is included in the hydrogen atom adsorption suppressing surface portion 9. The surface portion of the inner surface 7 substantially above the channel 16 is included in the hydrogen atom adsorption surface portion 8. Then, hydrogen atoms are substantially suppressed from being adsorbed in the main part of the surface portion of the inner surface 7 substantially above the two silicon layers 13, but substantially above the channel 16. It can be adsorbed on the surface portion of the inner surface 7. Thus, hydrogen atoms can only be adsorbed at the surface of the inner surface 7 substantially above the channel 16, where the adsorbed hydrogen atoms can affect the voltage shift in the sensor characteristics. . Furthermore, in the main part of the surface portion of the inner surface 7 substantially above the two silicon layers 13, hydrogen atoms cannot be substantially adsorbed, where the adsorbed hydrogen atoms are subjected to a voltage in the characteristics of the sensor. It cannot affect the shift. And at the surface portion of the inner surface 7 where hydrogen atoms cannot affect the voltage shift in the sensor characteristics, no hydrogen atoms are wasted. This should be apparent to those skilled in the art and will not be further described here. The term “above” is used to indicate the position of a portion on the inner surface 7 when the basic structure of the transistor has the orientation shown in FIG.

  Hydrogen gas sensitive semiconductor sensors are used as leak detectors in systems that use hydrogen gas, as leak detectors in systems and methods that use hydrogen gas as a tracer gas for testing and / or to locate leaks, or for example, hydrogen In the industry (petrochemical industry, electrochemical industry, gas factory, etc.) using gas or a mixture containing hydrogen gas, it can be used as an alarm detector for indicating the presence of hydrogen gas for the purpose of preventing explosion.

  For example, a hydrogen gas sensitive semiconductor sensor according to the present invention provides contact between a probe, ie, the outer surface of a catalytic metal layer in the sensor, and a gas sample in which the presence or concentration of hydrogen gas molecules is to be measured. It may be included in the configured device. The apparatus can be configured to contact the outer surface of the catalytic metal layer in the sensor with the gas sample, or to contact the gas sample with the outer surface of the catalytic metal layer in the sensor. For example, the probe may be a sampling unit. A hydrogen gas detection probe comprising a hydrogen gas sensitive semiconductor sensor according to the present invention is also within the scope of the present invention.

  Furthermore, a hydrogen gas detection system comprising a probe (which comprises a sensor according to the invention) and a measurement unit is also within the scope of the invention. The hydrogen gas molecules are then sensed by a sensor at the probe based on the hydrogen dipole transducer principle, and the signal from the sensor due to the detection of hydrogen gas molecules is measured and analyzed in a measurement unit. The measurement unit is typically referred to as a detector and may be of any suitable type.

  Furthermore, the hydrogen gas detection system according to the present invention also includes a probe (which includes the sensor according to the present invention) and a measurement unit, as well as a hydrogen gas source, a gas controller, a gas pressure regulator, and a test object mounting. At least one of the devices in the group of fixtures and fixture controllers is included. Such a system may be used for leak testing and / or leak location based on utilizing hydrogen gas as a tracer gas. The hydrogen gas source is configured to be a tracer gas source and may be of any suitable type. The gas controller is configured to manage the filling of hydrogen gas from a hydrogen gas source into a subject to be tested or into a housing such as a fixture surrounding the subject to be tested, and of any suitable type. May be. The gas pressure regulator is configured to control the output pressure from the gas source and may be of any suitable type. The fixture to be tested is configured to seal any other opening that does not constitute a leak, as well as to any suitable type as it is connected to the test subject for gas filling and removal. It may be. The fixture controller is configured to successfully handle fixture connections and seals and may be of any suitable type.

  For example, a system according to the present invention comprising a probe (which includes a sensor according to the present invention), a measurement unit, a hydrogen gas source, a gas controller, a gas pressure regulator, a fixture to be tested, and a fixture controller. When used for leak detection, an object undergoing a leak test is connected to a fixture. Use fixture controllers to handle fixture connections well. Subsequently, a gas or gas mixture containing a traceable amount of hydrogen is carried by the gas controller from the gas source into the test object under test. A gas pressure regulator is used to control the output pressure from the gas source. Subsequently, the probe surrounding the sensor is used to analyze the air surrounding the object under test for an increase in the presence of hydrogen. Any measurable increase in hydrogen concentration is presented by the measurement unit and is evidence of a leak present in the object being tested. Analogue methods detect leaks by managing a traceable gas or gas mixture outside the object under test and analyzing the air inside the object being tested for increased presence of hydrogen It is also possible to do.

  Thus, while the basic and novel features of the present invention have been illustrated, described and pointed out as applied to preferred embodiments of the present invention, the shapes and details of the depicted apparatus and various omissions in their operation have been shown. It will be understood that substitutions and modifications may be made by those skilled in the art without departing from the spirit of the invention. For example, all combinations of elements that perform substantially the same function in substantially the same way to achieve the same result are expressly intended to be within the scope of the invention. Further, the structures and / or elements illustrated and / or described in connection with any of the disclosed shapes or embodiments of the present invention are subject to any other disclosure, as a general matter of design choice, It should be understood that it can be incorporated into the description or proposed shape or embodiment. Accordingly, it is intended to be limited only as indicated by the claims appended hereto.

FIG. 2 is a schematic cross-sectional view of a basic structure and basic operation principle of a gas sensing element semiconductor sensor of the prior art, which operates based on the hydrogen dipole transducer principle and can be used for detection of hydrogen gas. 1 schematically shows a hydrogen dipole generated at the interface between a catalytic metal layer and an insulating layer of a gas sensitive semiconductor sensor operating on the hydrogen dipole transducer principle. It is a schematic sectional drawing of the basic structure in 1st Embodiment of the hydrogen gas sensing semiconductor sensor by this invention. It is a schematic sectional drawing of the basic structure in 2nd Embodiment of the hydrogen gas sensing semiconductor sensor by this invention. It is a schematic perspective view of the basic structure in 2nd Embodiment of the hydrogen gas sensing semiconductor sensor by this invention. It is a schematic perspective view of the basic structure in 3rd Embodiment of the hydrogen gas sensing semiconductor sensor by this invention. It is a schematic sectional drawing of the basic structure in 4th Embodiment of the hydrogen gas sensing semiconductor sensor by this invention. It is a schematic sectional drawing of the basic structure of the field effect transistor containing the basic structure in 1st Embodiment of the hydrogen gas sensing semiconductor sensor by this invention. It is a schematic sectional drawing of the basic structure of the field effect transistor containing the basic structure in 4th Embodiment of the hydrogen gas sensing semiconductor sensor by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Catalyst metal layer 2 Semiconductor layer 3 Insulating layer 4 Outer surface 5 Upper surface 6 Side surface 7 Inner surface 8 Hydrogen atom adsorption surface part 9 Hydrogen atom adsorption suppression surface part 10 Surface expansion structure 11 Hydrogen atom adsorption suppression material layer 12 p-type silicon semiconductor 13 n-type Silicon layer 14 Source electrode 15 Drain electrode 16 Channel

Claims (21)

A catalyst metal layer (1); a semiconductor layer (2); and an insulating layer (3) disposed between the catalyst metal layer (1) and the semiconductor layer (2). In a hydrogen gas sensing semiconductor sensor, wherein (1) has an outer surface (4) and an inner surface (7), and the outer surface (4) is configured to be in free communication with the ambient atmosphere,
The inner surface (7) includes at least one hydrogen atom adsorption surface portion (8), and each hydrogen atom adsorption surface portion (8) is disposed adjacent to the insulating layer (3);
The surface area of the outer surface (4) is at least 100% greater than the total surface area of all the at least one hydrogen atom adsorption surface portion (8) of the inner surface (7);
A hydrogen gas sensing semiconductor sensor.   The surface area of the outer surface (4) is at least 500% greater than the total surface area of all the at least one hydrogen atom adsorption surface portion (8) of the inner surface (7). Hydrogen gas sensing semiconductor sensor.   The surface area of the outer surface (4) is at least 5000% greater than the total surface area of all the at least one hydrogen atom adsorption surface portion (8) of the inner surface (7). The hydrogen gas sensing semiconductor sensor described.   The hydrogen gas sensing semiconductor sensor according to any one of claims 1 to 3, characterized in that the upper surface (5) of the catalytic metal layer (1) is provided with a surface expansion structure (10).   The hydrogen gas sensing semiconductor sensor according to claim 4, characterized in that the inner surface (7) comprises one hydrogen atom adsorption surface (8).   The inner surface (7) further includes at least one hydrogen atom adsorption suppressing surface portion (9), and the hydrogen atom adsorption suppressing material layer (11) includes each hydrogen atom adsorption suppressing surface portion (9) and the insulating layer (3). And each hydrogen atom adsorption inhibiting surface portion (9) is disposed adjacent to the hydrogen atom adsorption inhibiting material layer (11), and the thickness of the hydrogen atom adsorption inhibiting material layer (11) is The hydrogen gas sensing semiconductor sensor according to any one of claims 1 to 5, wherein the thickness is 0.001 to 0.3 µm.   The sensor includes at least two hydrogen atom adsorption inhibiting material layers (11), and all of the hydrogen atom adsorption inhibiting material layers (11) are the same hydrogen atom adsorption inhibiting material, The hydrogen gas sensing semiconductor sensor according to claim 6.   The sensor includes at least two hydrogen atom adsorption inhibiting material layers (11), and at least two of the hydrogen atom adsorption inhibiting material layers (11) are different hydrogen atom adsorption inhibiting materials. The hydrogen gas sensing semiconductor sensor according to claim 6.   The hydrogen gas sensing semiconductor sensor according to any one of claims 6 to 8, wherein the hydrogen atom adsorption suppressing material is a non-catalytic metal or a non-catalytic alloy.   The hydrogen gas sensing semiconductor sensor according to claim 9, wherein the hydrogen atom adsorption suppressing material is aluminum, an aluminum alloy, or chromium.   11. The hydrogen gas sensing semiconductor sensor according to claim 1, wherein the sensor is a metal / insulator / semiconductor field effect device.   The hydrogen gas sensing semiconductor sensor according to claim 1, wherein the sensor is a Schottky barrier device.   Use of a hydrogen gas sensitive semiconductor sensor according to any one of claims 1 to 12 for detecting the presence of hydrogen gas molecules in a gas sample.   Use of a hydrogen gas sensitive semiconductor sensor according to any one of claims 1 to 12 for measuring the concentration of hydrogen gas molecules in a gas sample.   A hydrogen gas detection probe comprising the hydrogen gas sensing semiconductor sensor according to any one of claims 1 to 12.   A hydrogen gas detection system comprising a probe and a measurement unit, wherein the probe has the hydrogen gas sensing semiconductor sensor according to claim 1.   The hydrogen gas detection system according to claim 16, wherein the system further comprises a hydrogen gas source.   The hydrogen gas detection system according to claim 16, wherein the system further includes a gas controller.   The hydrogen gas detection system according to any one of claims 16 to 18, wherein the system further includes a fixture for a test object.   20. The hydrogen gas detection system according to any one of claims 16 to 19, wherein the system further comprises a gas pressure regulator.   21. The hydrogen gas detection system according to any one of claims 16 to 20, wherein the system further comprises a fixture controller.

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