Hydrogen detection device and control method for hydrogen detection device

Abstract

This hydrogen detection device (10) comprises a hydrogen sensor (100) and a detection circuit (200), wherein: the hydrogen sensor (100) includes a first electrode (103), a second electrode (106), a metal oxide layer (104), a first insulating film (insulating films 107a to 107c), a first terminal (TE1), and a second terminal (TE2) which are connected via a via (108) to the other surface of the second electrode (106) facing the main surface thereof, and a third terminal (BE) connected via the via (108) to the other surface of the first electrode (103) facing the main surface thereof; and the detection circuit (200) includes ammeters (230 and 231) for measuring (1) a first resistance value between the first terminal (TE1) and the second terminal (TE2) and (2) a second resistance value between at least one among the first terminal (TE1) and the second terminal (TE2) and the third terminal (BE), and a control circuit (210) that selectively outputs either the first resistance value or the second resistance value.

Description

Technical Field

[0001] The present disclosure relates to a hydrogen detection device and a method for controlling the hydrogen detection device, and particularly to a wide-range hydrogen detection device that detects hydrogen at low and high concentrations.

Background Art

[0002] Conventionally, a wide-range hydrogen detection device that detects hydrogen at low and high concentrations has been proposed (see, for example, Patent Document 1). According to the technique of Patent Document 1, the leak detection means has two modes: a leak detection mode and a gas concentration measurement mode. This eliminates the waiting time due to the fatigue of the gas sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technique of Patent Document 1 described above, a valve is required to switch the flow path between a state in which the sample gas is supplied to the first gas sensor and the background gas is supplied to the second gas sensor, and a state in which the sample gas is supplied to the second gas sensor and the background gas is supplied to the first gas sensor. Therefore, there is a problem that the hydrogen detection device becomes large-sized.

[0005] Therefore, an object of the present disclosure is to provide a small-sized and wide-range hydrogen detection device that detects hydrogen at low and high concentrations.

Means for Solving the Problems

[0006] To achieve the above objective, a hydrogen detection device according to one embodiment of the present disclosure comprises a first hydrogen sensor and a second hydrogen sensor for detecting hydrogen, and a first detection circuit connected to the first hydrogen sensor and the second hydrogen sensor, wherein the first hydrogen sensor has a first electrode and a second electrode arranged with their main surfaces facing each other, a first metal oxide layer arranged in contact with the main surface of the first electrode and the main surface of the second electrode, a first insulating film covering the first electrode, the second electrode and the first metal oxide layer, a first terminal and a second terminal connected via via to the other surface of the second electrode facing the main surface, and a third terminal connected via via to the other surface of the first electrode facing the main surface, wherein the first insulating film has a first opening between the first terminal and the second terminal in a plan view with respect to the second electrode, exposing the other surface of the second electrode without being covered by the first insulating film. The second hydrogen sensor includes a third electrode and a fourth electrode with their main surfaces facing each other, a second metal oxide layer positioned in contact with the main surface of the third electrode and the main surface of the fourth electrode, a second insulating film covering the third electrode, the fourth electrode and the second metal oxide layer, a fourth terminal and a fifth terminal connected via vias to the other surface of the fourth electrode facing the main surface, and a sixth terminal connected via vias to the other surface of the third electrode facing the main surface, wherein the second insulating film has a second opening between the fourth terminal and the fifth terminal in a plan view of the fourth electrode, exposing the other surface of the fourth electrode without being covered by the second insulating film, and the first detection circuit includes a first measurement circuit for measuring a first resistance value between the first terminal and the second terminal, and a second resistance value between at least one of the fourth terminal and the fifth terminal and the sixth terminal.

[0007] To achieve the above objective, a control method for a hydrogen detection device according to one embodiment of the present disclosure is a control method for a hydrogen detection device, wherein the first detection circuit acquires the first resistance value and selectively outputs either the first resistance value or the second resistance value based on the acquired first resistance value. [Effects of the Invention]

[0008] This disclosure provides a compact hydrogen detection device with a wide range of capabilities for detecting both low and high concentrations of hydrogen. [Brief explanation of the drawing]

[0009] [Figure 1A] Figure 1A is a cross-sectional view showing an example of the configuration of a hydrogen sensor in an embodiment. [Figure 1B] Figure 1B is a top view showing an example of the configuration of a hydrogen sensor in an embodiment. [Figure 2A] Figure 2A is a block diagram showing an example configuration of a hydrogen detection device according to an embodiment. [Figure 2B] Figure 2B shows an example of voltage application when the hydrogen detection device shown in Figure 2A is driven in horizontal mode. [Figure 2C] Figure 2C shows an example of voltage application when the hydrogen detection device shown in Figure 2A is driven in vertical mode. [Figure 3A] Figure 3A shows an example of actual measurement (waveform of detected current) in horizontal mode using the hydrogen detection device according to the embodiment. [Figure 3B] Figure 3B is a graph showing the relationship between the detected current (horizontal axis) obtained in Figure 3A and the hydrogen concentration at that time (vertical axis). [Figure 4A] Figure 4A shows an example of actual measurement (waveform of detected current) in vertical mode using the hydrogen detection device according to the embodiment. [Figure 4B] Figure 4B is a graph showing the relationship between the detected current (horizontal axis) obtained in Figure 4A and the hydrogen concentration at that time (vertical axis). [Figure 5] Figure 5 is a flowchart showing an example of the operation (control method of the hydrogen detection device) of the hydrogen detection device shown in Figure 2A. [Figure 6] Figure 6 is a block diagram showing an example of the configuration of a hydrogen detection device according to a first modified example of the embodiment. [Figure 7] Figure 7 is a flowchart showing an example of the operation of the hydrogen detection device according to the first modified example shown in Figure 6. [Figure 8]FIG. 8 is a block diagram showing a configuration example of a hydrogen detection device according to a second modification of the embodiment. [Figure 9] FIG. 9 is a block diagram showing a configuration example of a hydrogen detection device according to a third modification of the embodiment. [Figure 10] FIG. 10 is a block diagram showing a configuration example of a hydrogen detection device according to a fourth modification of the embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing a configuration example of a resistor with a fixed resistance value that can be applied to one of the two hydrogen sensors constituting the first bridge circuit and one of the two hydrogen sensors constituting the second bridge circuit in FIG. 10. [Figure 12] FIG. 12 is a block diagram showing a configuration example of a hydrogen detection device according to a fifth modification of the embodiment. [Figure 13A] FIG. 13A is a block diagram showing a configuration example of a hydrogen detection device according to a sixth modification of the embodiment. [Figure 13B] FIG. 13B is an equivalent circuit diagram of the hydrogen detection device shown in FIG. 13A.

DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that each of the embodiments described below shows a specific example of the present disclosure. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, steps, order of steps, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Also, each figure is not necessarily drawn precisely. In each figure, substantially the same configuration is denoted by the same reference numeral, and overlapping descriptions are omitted or simplified.

[0011] FIG. 1A is a cross-sectional view showing a configuration example of a hydrogen sensor 100 according to an embodiment. of embodiment In a state FIG. 1B is a top view showing a configuration example of the hydrogen sensor 100 in the embodiment. Note that FIG. 1A shows a schematic cross-section of the cross-section taken along the cutting line IA-IA of FIG. 1B as viewed in the arrow direction. In a state

[0012]

[0012] The hydrogen sensor 100 is a fine structure that can be manufactured in the semiconductor manufacturing process, and is a wide-range hydrogen sensor that can detect low and high concentrations of hydrogen. Its main structure includes a first electrode 103 and a second electrode 106 with their main surfaces facing each other, a metal oxide layer 104 placed in contact with the main surface of the first electrode 103 and the main surface of the second electrode 106, insulating films 107a to 107c, 109a and 109b covering the first electrode 103, the second electrode 106 and the metal oxide layer 104, a first terminal TE1 and a second terminal TE2 connected via via to the other surface of the second electrode 106 facing the main surface, and a third terminal BE connected via via to the other surface of the first electrode 103 facing the main surface. The insulating film 107b has an opening 106a between the first terminal TE1 and the second terminal TE2 in a plan view with respect to the second electrode 106, which exposes the other side of the second electrode 106 without being covered by the insulating film 107b.

[0013] The first electrode 103 is a planar electrode having two surfaces. One of the two surfaces of the first electrode 103 (i.e., the upper surface in Figure 1A) is in contact with the metal oxide layer 104, and the other surface (i.e., the lower surface in Figure 1A) is in contact with the insulating film 107a and the via 108. In Figure 1B, the first electrode 103 is rectangular in shape and the same size as the second electrode 106. The first electrode 103 may be made of a material with a lower standard electrode potential compared to the metal constituting the metal oxide, such as tungsten, nickel, tantalum, titanium, aluminum, tantalum nitride, or titanium nitride. A higher standard electrode potential indicates a property that is less susceptible to oxidation. The first electrode 103 in Figure 1A is formed of a transition metal nitride such as tantalum nitride (TaN) or titanium nitride (TiN), or a stack thereof.

[0014] The metal oxide layer 104 is sandwiched between the two opposing main surfaces of the first electrode 103 and the second electrode 106, and is composed of a metal oxide as a gas-sensitive resistive film, having a resistance value that reversibly changes depending on the presence or absence of hydrogen-containing gas in the gas in contact with the second electrode 106. The metal oxide layer 104 only needs to have the property of its resistance changing with the presence of hydrogen. For example, the metal oxide layer 104 is composed of an oxygen-deficient type metal oxide. The base metal of the metal oxide layer 104 may be selected from at least one of transition metals such as tantalum (Ta), hafnium (Hf), titanium (Ti), zirconium (Zr), niobium (Nb), tungsten (W), nickel (Ni), and iron (Fe), and aluminum (Al).

[0015] Because transition metals can exist in multiple oxidation states, different resistance states can be achieved through oxidation-reduction reactions. Here, the "oxygen deficiency" of a metal oxide refers to the ratio of the oxygen deficiency in the metal oxide to the amount of oxygen in an oxide of the same stoichiometric composition composed of the same elements. Here, the oxygen deficiency is the value obtained by subtracting the amount of oxygen in the metal oxide from the amount of oxygen in the metal oxide of the same stoichiometric composition. If there may be multiple metal oxides of the same stoichiometric composition composed of the same elements, the oxygen deficiency of the metal oxide is defined based on the one with the highest resistance value among those stoichiometric metal oxides. Stoichiometric metal oxides are more stable and have higher resistance values ​​compared to metal oxides of other compositions.

[0016] For example, if the base metal of the metal oxide layer 104 is tantalum (Ta), then the oxide with a stoichiometric composition according to the above definition is Ta2O5, so TaO 2.5 It can be expressed as follows: TaO 2.5 The oxygen deficiency level is 0%, TaO 1.5The oxygen deficiency is (2.5-1.5) / 2.5 = 40%. Furthermore, metal oxides with excess oxygen will have a negative oxygen deficiency. In this disclosure, unless otherwise specified, the oxygen deficiency can be positive, zero, or negative. Oxides with a low oxygen deficiency are closer to the stoichiometric composition of the oxide and therefore have higher resistance values, while oxides with a high oxygen deficiency are closer to the metal that constitutes the oxide and therefore have lower resistance values.

[0017] The metal oxide layer 104 shown in Figure 1A has a first layer 104a in contact with the first electrode 103, a second layer 104b in contact with the first layer 104a and the second electrode 106, and an insulating separation layer 104i. The oxygen deficiency of the second layer 104b is smaller than that of the first layer 104a. For example, the first layer 104a is TaO X The second layer 104b is Ta2O5, which has a lower oxygen deficiency than the first layer 104a. The metal oxide layer 104 also has an insulating separation layer 104i on the outer periphery of the first electrode 103 in a plan view.

[0018] Here, "planar view" refers to viewing the hydrogen sensor 100 according to this disclosure from a viewpoint in the stacking direction of Figure 1A, in other words, from a viewpoint in the direction normal to any of the planar first electrode 103, the planar second electrode 106, etc., for example, when viewing the top surface of the hydrogen sensor 100 shown in Figure 1B.

[0019] The resistance of the metal oxide layer 104 decreases depending on the amount of hydrogen-containing gas in contact with the second electrode 106 (the greater the amount). Specifically, when hydrogen-containing gas is present in the gas being detected, hydrogen atoms are dissociated from the hydrogen-containing gas at the second electrode 106. The dissociated hydrogen atoms penetrate into the metal oxide layer 104 and form impurity levels. In particular, they concentrate near the interface with the second electrode 106, effectively reducing the thickness of the second layer 104b. As a result, the resistance of the metal oxide layer 104 decreases.

[0020] The second electrode 106 is a planar electrode with hydrogen dissociation properties and has two surfaces. One of the two surfaces of the second electrode 106 (i.e., the lower surface in Figure 1A) is in contact with the metal oxide layer 104, and the other surface (i.e., the upper surface in Figure 1A) is in contact with the metal layer 106s and the outside air. The second electrode 106 has an exposed portion 106e within the opening 106a that is exposed to the outside air. The second electrode 106 is made of a material that has catalytic activity in dissociating hydrogen atoms from gas molecules containing hydrogen atoms, such as a precious metal such as platinum (Pt), iridium (Ir), or palladium (Pd), or nickel (Ni), or an alloy containing at least one of these. The second electrode 106 in Figure 1A is assumed to be platinum (Pt). Two terminals, namely the first terminal TE1 and the second terminal TE2, are connected to the second electrode 106.

[0021] The first terminal TE1 is connected to the second electrode 106 via via 108.

[0022] The second terminal TE2 is connected to the second electrode 106 via via 108. The first terminal TE1 and the second terminal TE2 are connected to an external detection circuit that drives the hydrogen sensor 100 via openings TE1a and TE2a.

[0023] As shown in Figure 1B, the first terminal TE1 and the second terminal TE2 are positioned on either side of the exposed portion 106e in a plan view of the second electrode 106. This arrangement allows a predetermined voltage to be applied between the first terminal TE1 and the second terminal TE2, thereby energizing the exposed portion 106e of the second electrode 106, i.e., allowing current to flow through the exposed portion 106e. This energization of the exposed portion 106e of the second electrode 106 is thought to activate the hydrogen dissociation process of the exposed portion 106e. Note that the predetermined voltages may have opposite polarities.

[0024] The hydrogen sensor 100 changes the resistance between the first terminal TE1 and the second terminal TE2 when gas molecules containing hydrogen atoms come into contact with the exposed portion 106e while the exposed portion 106e is energized. The detection circuit detects this change in resistance (this detection is also called "lateral mode"), thereby detecting gas molecules containing low concentrations of hydrogen atoms.

[0025] The third terminal BE is connected to the first electrode 103 via the opening BEa, via 108, wiring 114, and via 108. The third terminal BE is connected via the opening BEa to an external detection circuit that drives the hydrogen sensor 100. The hydrogen sensor 100 changes the resistance between the first electrode 103 and the second electrode 106 when gas molecules containing hydrogen atoms come into contact with the exposed portion 106e while the exposed portion 106e is energized. In other words, the hydrogen sensor 100 changes the resistance between at least one of the first terminal TE1 and the second terminal TE2 and the third terminal BE when gas molecules containing hydrogen atoms come into contact with the exposed portion 106e while the exposed portion 106e is energized. The detection circuit also detects this change in resistance (this detection is also called "vertical mode") to detect gas molecules containing a high concentration of hydrogen atoms.

[0026] Furthermore, the insulating films 102, 107a to 107c, 109a and 109b that cover the main parts of the hydrogen sensor 100 are formed from silicon oxide films, silicon nitride films, and the like.

[0027] Furthermore, a metal layer 106s is formed on the upper surface of the second electrode 106 other than the opening 106a. The metal layer 106s is made of material such as TiAlN and is formed as an etching stopper for via 108 formation, but it is not essential.

[0028] Furthermore, the laminate of the first electrode 103, the metal oxide layer 104, and the second electrode 106 is an element that can be used as a memory element for resistive random-access memory (ReRAM). In resistive random-access memory, two states of the metal oxide layer 104, a high-resistance state and a low-resistance state, are used to create a digital memory element. In the hydrogen sensor 100 of this disclosure, the high-resistance state of the metal oxide layer 104 is used.

[0029] Note that in Figure 1A, the metal oxide layer 104 is TaO x An example of a two-layer structure consisting of a first layer 104a made of and a second layer 104b made of Ta2O5 with a low oxygen deficiency was shown, but Ta2O5 or TaO x A single-layer structure using this material is also acceptable.

[0030] Figure 2A is a block diagram showing an example configuration of the hydrogen detection device 10 according to an embodiment. The hydrogen detection device 10 is a wide-range hydrogen detection device that detects low and high concentrations of hydrogen by dynamically and selectively driving the hydrogen sensor 100 shown in Figures 1A and 1B in either a horizontal mode or a vertical mode, and comprises the hydrogen sensor 100 shown in Figures 1A and 1B and a detection circuit 200 connected to the hydrogen sensor 100.

[0031] The detection circuit 200 includes a control circuit 210, a drive circuit 220, and ammeters 230 and 231.

[0032] The ammeter 230 is a measurement circuit that measures the current flowing through the hydrogen sensor 100 in horizontal mode, that is, the current flowing between the first terminal TE1 and the second terminal TE2 of the hydrogen sensor 100.

[0033] The ammeter 231 is a measuring circuit that measures the current flowing through the hydrogen sensor 100 in vertical mode, that is, the current flowing between at least one of the first terminal TE1 and the second terminal TE2 of the hydrogen sensor 100 and the third terminal BE.

[0034] When the drive circuit 220 drives the hydrogen sensor 100 in horizontal mode according to the instruction CMD2 from the control circuit 210, it reads the value of the current flowing through the ammeter 230 (current value I1) with the potentials shown in Figure 2B (0.25V, -0.25V, 1.5V) applied to the first terminal TE1, the second terminal TE2, and the third terminal BE, respectively, and returns the read current value I1 to the control circuit 210. On the other hand, when the drive circuit 220 drives the hydrogen sensor 100 in vertical mode, it reads the value of the current flowing through the ammeter 231 (current value I2) with the potentials shown in Figure 2C (0.25V, -0.25V, -2.2V) applied to the first terminal TE1, the second terminal TE2, and the third terminal BE, respectively, and returns the read current value I2 to the control circuit 210. Note that the applied voltages shown in Figures 2B and 2C are examples and are not limited to these values.

[0035] When the control circuit 210 receives an instruction CMD1 from an external source, it communicates with the drive circuit 220 to dynamically determine a mode (horizontal mode / vertical mode) suitable for the current hydrogen concentration using the hydrogen sensor 100, calculates the resistance value (R1 or R2) of the hydrogen sensor 100 in the determined mode, and outputs it externally. Specifically, the control circuit 210 calculates the resistance value (R1 or R2) of the hydrogen sensor 100 from the current value (I1 or I2) obtained from the drive circuit 220 and the voltage value applied to the hydrogen sensor 100 by the drive circuit 220. The control circuit 210 may consist of a memory storing a program and a processor that executes the program, or it may be a logic circuit / sequencer that sequentially executes processing according to the instruction CMD1 given from an external source. In addition, the control circuit 210 may output the hydrogen concentration converted from the resistance value of the hydrogen sensor 100, either in lieu of the resistance value or along with the resistance value.

[0036] Figure 3A shows an example of actual measurement in horizontal mode using the hydrogen detection device 10 according to the embodiment (waveform of the detection current obtained by the ammeter 230). Figure 3B is a graph showing the relationship between the detection current (horizontal axis) obtained in Figure 3A and the hydrogen concentration at that time (vertical axis). As shown in Figure 3A, in this example, the hydrogen sensor 100 is intermittently exposed to hydrogen of predetermined concentrations (0.01%, 0.1%, and 1.0% from left to right) three times. In Figure 3B, points corresponding to the current flowing through the hydrogen sensor 100 in horizontal mode during hydrogen exposure in Figure 3A and the hydrogen concentration at that time are plotted. The hydrogen concentration value is expressed as a percentage (%) of the gas volume ratio.

[0037] Figure 4A shows an example of actual measurement in vertical mode using the hydrogen detection device 10 according to the embodiment (waveform of the detection current obtained by the ammeter 231). Figure 4B is a graph showing the relationship between the detection current (horizontal axis) obtained in Figure 4A and the hydrogen concentration at that time (vertical axis). As shown in Figure 4A, in this example, the hydrogen sensor 100 is intermittently exposed to hydrogen of predetermined concentrations (1.0%, 2.0%, 3.0%, and 4.0% from left to right) four times. In Figure 4B, points corresponding to the current flowing through the hydrogen sensor 100 in vertical mode during hydrogen exposure in Figure 4A and the hydrogen concentration at that time are plotted.

[0038] As can be seen from Figures 3A and 3B, which show the characteristics of the hydrogen sensor 100 in horizontal mode, and Figures 4A and 4B, which show the characteristics of the hydrogen sensor 100 in vertical mode (especially the vertical axis in Figure 3B and Figure 4B), in horizontal mode, the detection current increases approximately linearly with respect to the logarithmic increase in concentration for low concentrations of hydrogen, including the range of 0.01 to 1%. On the other hand, in vertical mode, the detection current increases approximately proportionally to the concentration for high concentrations of hydrogen, including the range of 1.0 to 4.0%. In other words, the hydrogen sensor 100 detects low concentrations of hydrogen in horizontal mode and high concentrations of hydrogen in vertical mode. Furthermore, in horizontal mode, the hydrogen sensor 100 detects low concentrations of hydrogen exceeding the concentration range shown in Figure 3B, and in vertical mode, it detects high concentrations of hydrogen exceeding the concentration range shown in Figure 4B.

[0039] Figure 5 is a flowchart illustrating an example of the operation (control method of the hydrogen detection device 10) shown in Figure 2A. Here, the process of the hydrogen detection device 10 detecting the hydrogen concentration while dynamically switching between horizontal and vertical modes is shown.

[0040] When the control circuit 210 of the hydrogen detection device 10 receives an instruction CMD1 from an external source indicating the start of detection, it first detects the hydrogen concentration in horizontal mode (S10). Specifically, the control circuit 210 controls the drive circuit 220 to apply the potentials shown in Figure 2B (0.25V, -0.25V, 1.5V) to the first terminal TE1, the second terminal TE2, and the third terminal BE, respectively, and reads the value of the current flowing through the ammeter 230 (current value I1) via the drive circuit 220, repeating this process by pulse voltage driving the hydrogen sensor 100. The control circuit 210 calculates the resistance value R1 of the hydrogen sensor 100 from the current value I1 obtained from the drive circuit 220 and the voltage value applied by the drive circuit 220 to the hydrogen sensor 100, and outputs the calculated resistance value (R1 or the hydrogen concentration converted from the resistance value R1) to the outside.

[0041] Here, the control circuit 210 determines whether the hydrogen concentration obtained from the resistance value R1 exceeds a threshold (for example, a hydrogen concentration of 1%) each time it obtains the hydrogen concentration (S11).

[0042] As a result, if the obtained hydrogen concentration exceeds a threshold (for example, a hydrogen concentration of 1%), then (S11) Yes) The control circuit 210 switches from horizontal mode to vertical mode to detect the hydrogen concentration (S12). Specifically, the control circuit 210 controls the drive circuit 220 to apply the potentials shown in Figure 2C (0.25V, -0.25V, -2.2V) to the first terminal TE1, the second terminal TE2, and the third terminal BE, respectively, and reads the value of the current flowing through the ammeter 231 (current value I2) via the drive circuit 220, repeating this process by pulse voltage driving the hydrogen sensor 100. The control circuit 210 calculates the resistance value R2 of the hydrogen sensor 100 from the current value I2 obtained from the drive circuit 220 and the voltage value applied by the drive circuit 220 to the hydrogen sensor 100, and outputs the calculated resistance value R2 (or the hydrogen concentration converted from the resistance value R2) to the outside.

[0043] On the other hand, if the obtained hydrogen concentration does not exceed a threshold (for example, 1% hydrogen concentration) (No in S11), the control circuit 210 continues hydrogen detection in lateral mode.

[0044] Furthermore, if the detected hydrogen concentration falls below a threshold (for example, 1% hydrogen concentration) after detection in vertical mode, the control circuit 210 may switch from vertical mode to horizontal mode.

[0045] As described above, the hydrogen detection device 10 according to this embodiment comprises a first hydrogen sensor (hydrogen sensor 100) for detecting hydrogen, and a third detection circuit (detection circuit 200) connected to the first hydrogen sensor (hydrogen sensor 100). The first hydrogen sensor (hydrogen sensor 100) comprises a first electrode 103 and a second electrode 106 arranged with their main surfaces facing each other, a first metal oxide layer (metal oxide layer 104) arranged in contact with the main surface of the first electrode 103 and the main surface of the second electrode 106, a first insulating film (insulating film 107a to 107c, etc.) covering the first electrode 103, the second electrode 106 and the first metal oxide layer (metal oxide layer 104), a first terminal TE1 and a second terminal TE2 connected via a via 108 to the other surface of the second electrode 106 facing the main surface, and the main surface of the first electrode 103. The second electrode 106 has a third terminal BE connected via a via 108 to the other side facing the first electrode 106, and the first insulating film (insulating films 107a to 107c, etc.) has a first opening (opening 106a) between the first terminal TE1 and the second terminal TE2 in a plan view with respect to the second electrode 106, which exposes the other side of the second electrode 106 without being covered by the first insulating film (insulating films 107a to 107c, etc.). The third detection circuit (detection circuit 200) has a third measurement circuit (ammeters 230 and 231, respectively) that measures a first resistance value between the first terminal TE1 and the second terminal TE2, and a second resistance value between at least one of the first terminal TE1 and the second terminal TE2 and the third terminal BE, and a second control circuit (control circuit 210) that selectively outputs either the first resistance value or the second resistance value.

[0046] This allows for the detection of both low and high concentrations of hydrogen simply by switching the drive mode for the hydrogen sensor 100, which is a microstructure that can be manufactured in the semiconductor manufacturing process. Therefore, compared to conventional systems, valves for switching gas flow paths are unnecessary, resulting in a compact hydrogen detection device 10 that can detect both low and high concentrations of hydrogen over a wide range.

[0047] Furthermore, the second control circuit (control circuit 210) selectively outputs either the first resistance value or the second resistance value based on the first resistance value. This allows the appropriate drive mode to be dynamically determined according to the actual hydrogen concentration, and hydrogen detection to be performed within the appropriate measurement range.

[0048] Furthermore, the first resistance value is more dependent on low hydrogen concentrations than the second resistance value. This allows for hydrogen detection within an appropriate measurement range by driving the hydrogen sensor 100 in horizontal mode for low hydrogen concentrations and in vertical mode for high hydrogen concentrations.

[0049] Furthermore, the first metal oxide layer (metal oxide layer 104) is composed of a transition metal oxide. The first electrode 103 is composed of a transition metal nitride, and the second electrode 106 is composed of a noble metal. This realizes a hydrogen detection device 10 whose resistance value changes sensitively to hydrogen.

[0050] Furthermore, in the control method of the hydrogen detection device 10 according to this embodiment, the third detection circuit (detection circuit 200) acquires a first resistance value and selectively outputs either the first resistance value or the second resistance value based on the acquired first resistance value.

[0051] This allows for the selective detection of both low and high concentrations of hydrogen simply by switching the drive mode for the minute hydrogen sensor 100. Therefore, compared to conventional systems, valves for switching gas flow paths are unnecessary, resulting in a compact hydrogen detection device 10 with a wide range of detection capabilities for both low and high concentrations.

[0052] Figure 6 is a block diagram showing an example configuration of a hydrogen detection device 10a according to the first modified embodiment. The hydrogen detection device 10a according to this modified embodiment has a configuration in which a spare hydrogen sensor is added to the hydrogen detection device 10 according to the embodiment. More specifically, the hydrogen detection device 10a includes, in addition to the configuration of the hydrogen detection device 10 according to the embodiment, a spare hydrogen sensor 110 and three switching circuits 20a to 20c.

[0053] The backup hydrogen sensor 110 is a backup hydrogen sensor having the same structure as the hydrogen sensor 100.

[0054] The three switching circuits 20a to 20c are all switches composed of two single-pole double-throw (SPDT) switches. Switching circuit 20a switches the conduction / non-conduction between the detection circuit 200 and the first terminal TE1 and second terminal TE2 of the hydrogen sensor 100, under the control of the control circuit 210 of the detection circuit 200. Switching circuit 20b switches the conduction / non-conduction between the detection circuit 200 and the first terminal TE1 and second terminal TE2 of the auxiliary hydrogen sensor 110, under the control of the control circuit 210 of the detection circuit 200. Switching circuit 20c switches the conduction / non-conduction between the detection circuit 200 and the third terminal BE of the hydrogen sensor 100 and the third terminal BE of the auxiliary hydrogen sensor 110, under the control of the control circuit 210 of the detection circuit 200.

[0055] Figure 7 is a flowchart showing an example of the operation of the hydrogen detection device 10a according to the first modified example shown in Figure 6. Here, the process of dynamically switching the hydrogen sensor used by the hydrogen detection device 10a from the hydrogen sensor 100 to the backup hydrogen sensor 110 is shown.

[0056] The control circuit 210 normally connects the hydrogen sensor 100 to the detection circuit 200 by controlling the switching circuits 20a to 20c, and uses the hydrogen sensor 100 to perform hydrogen detection as shown in the flowchart of Figure 5. In parallel with hydrogen detection, the control circuit 210 determines whether the hydrogen sensor 100 is functioning normally or abnormally (S20). Specifically, the control circuit 210 determines whether the resistance value at the hydrogen sensor 100 is within a predetermined range (for example, a resistance value corresponding to a hydrogen concentration range of 0 to 1% in horizontal mode, and a resistance value corresponding to a hydrogen concentration range of 1.0 to 100% in vertical mode), thereby determining whether it is functioning normally or abnormally.

[0057] As a result, if it is determined that the system is normal (Yes in S20), the control circuit 210 continues hydrogen detection using the hydrogen sensor 100. On the other hand, if it is determined that the system is abnormal (No in S20), the control circuit 210 controls the switching circuits 20a to 20c to switch the hydrogen sensor connected to the detection circuit 200 from the hydrogen sensor 100 to the backup hydrogen sensor 110, and performs hydrogen detection using the backup hydrogen sensor 110 (S21).

[0058] As described above, the hydrogen detection device 10a according to the first modified example includes, in addition to the configuration of the hydrogen detection device 10 according to the embodiment, a backup hydrogen sensor 110 having the same structure as the first hydrogen sensor (hydrogen sensor 100), and a third switching circuit (switching circuits 20a to 20c) that selectively connects either the first hydrogen sensor (hydrogen sensor 100) or the backup hydrogen sensor (backup hydrogen sensor 110) to the third detection circuit (detection circuit 200). This improves user convenience because even if one hydrogen sensor 100 fails, hydrogen detection can be continued using the backup hydrogen sensor 110.

[0059] Figure 8 is a block diagram showing an example configuration of the hydrogen detection device 10b according to a second modified example of the embodiment. The hydrogen detection device 10b according to this modified example includes a hydrogen sensor exclusively for horizontal mode and a hydrogen sensor exclusively for vertical mode. More specifically, the hydrogen detection device 10b includes a hydrogen sensor 100a exclusively for horizontal mode and a hydrogen sensor 100b exclusively for vertical mode, instead of the hydrogen sensor 100 corresponding to both modes in the embodiment. The inclusion of switching circuits 20a to 20c is the same as in the first modified example.

[0060] The hydrogen sensor 100a, which is exclusively for horizontal mode, may be the same as the hydrogen sensor 100 according to the embodiment, or it may be an improved version of the hydrogen sensor 100 according to the embodiment, with enhanced materials or structure to improve sensitivity in horizontal mode.

[0061] The hydrogen sensor 100b, which is exclusively for vertical mode, may be the same as the hydrogen sensor 100 according to the embodiment, or it may be an improved version of the hydrogen sensor 100 according to the embodiment, with enhanced materials or structure to improve sensitivity in vertical mode.

[0062] The three switching circuits 20a to 20c are all switches composed of two single-pole double-throw (SPDT) switches. Switching circuit 20a switches the conduction / non-conduction between the detection circuit 200 and the first terminal TE1 and second terminal TE2 of the hydrogen sensor 100a, which is dedicated to horizontal mode, under the control of the control circuit 210 of the detection circuit 200. Switching circuit 20b switches the conduction / non-conduction between the detection circuit 200 and the first terminal TE1 and second terminal TE2 of the hydrogen sensor 100b, which is dedicated to vertical mode, under the control of the control circuit 210 of the detection circuit 200. Switching circuit 20c switches the conduction / non-conduction between the detection circuit 200 and the third terminal BE of the hydrogen sensor 100a, which is dedicated to horizontal mode, and the third terminal BE of the hydrogen sensor 100b, which is dedicated to vertical mode, under the control of the control circuit 210 of the detection circuit 200.

[0063] The operation of the hydrogen detection device 10b in this modified example (control method of the hydrogen detection device 10b) is the same as, for example, the flowchart shown in Figure 5. That is, the control circuit 210 of the hydrogen detection device 10b controls the switching circuits 20a to 20c to connect the hydrogen sensor 100a, which is exclusively for horizontal mode, to the detection circuit 200, and uses the hydrogen sensor 100a, which is exclusively for horizontal mode, to detect low concentrations of hydrogen in horizontal mode (S10).

[0064] Here, the control circuit 210 determines whether the hydrogen concentration (calculated from the resistance value) exceeds a threshold (for example, a hydrogen concentration of 1%) each time it obtains the hydrogen concentration (S11).

[0065] As a result, if the obtained hydrogen concentration exceeds a threshold (for example, 1% hydrogen concentration) (Yes in S11), the control circuit 210 controls the switching circuits 20a to 20c to switch the hydrogen sensor connected to the detection circuit 200 from the hydrogen sensor 100a, which is dedicated to horizontal mode, to the hydrogen sensor 100b, which is dedicated to vertical mode, and detects the hydrogen concentration (S12).

[0066] On the other hand, if the obtained hydrogen concentration does not exceed a threshold (for example, a hydrogen concentration of 1%) (No in S11), the control circuit 210 continues hydrogen detection using the hydrogen sensor 100a, which is dedicated to the horizontal mode.

[0067] Thus, the hydrogen detection device 10b according to the second modified example comprises a first hydrogen sensor (hydrogen sensor 100a for horizontal mode only) and a second hydrogen sensor (hydrogen sensor 100b for vertical mode only) for detecting hydrogen, and a first detection circuit (detection circuit 200) connected to the first hydrogen sensor (hydrogen sensor 100a for horizontal mode only) and the second hydrogen sensor (hydrogen sensor 100b for vertical mode only). The first hydrogen sensor (hydrogen sensor 100a for horizontal mode only) comprises a first electrode 103 and a second electrode 106 arranged with their main surfaces facing each other, a first metal oxide layer (metal oxide layer 104) arranged in contact with the main surface of the first electrode 103 and the main surface of the second electrode 106, a first insulating film (insulating film 107a to 107c, etc.) covering the first electrode 103, the second electrode 106 and the first metal oxide layer (metal oxide layer 104), and a via 10 on the other surface facing the main surface of the second electrode 106. The electrode has a first terminal TE1 and a second terminal TE2 connected via 8, and a third terminal BE connected via via 108 to the other surface of the first electrode 103 facing the main surface. The first insulating film (insulating films 107a to 107c, etc.) has a first opening (opening 106a) between the first terminal TE1 and the second terminal TE2 in a plan view with respect to the second electrode 106, which exposes the other surface of the second electrode 106 without being covered by the first insulating film (insulating films 107a to 107c, etc.).The second hydrogen sensor (hydrogen sensor 100b for vertical mode only) comprises a third electrode (first electrode 103) and a fourth electrode (second electrode 106) arranged with their main surfaces facing each other, a second metal oxide layer (metal oxide layer 104) arranged in contact with the main surface of the third electrode (first electrode 103) and the main surface of the fourth electrode (second electrode 106), a second insulating film (insulating film 107a to 107c, etc.) covering the third electrode (first electrode 103), the fourth electrode (second electrode 106), and the second metal oxide layer (metal oxide layer 104), a fourth terminal and a fifth terminal (first terminal TE1 and second terminal TE2) connected via via 108 to the other surface of the fourth electrode (second electrode 106) facing the main surface, and a via 108 connected to the other surface of the third electrode (first electrode 103) facing the main surface The device has a sixth terminal (third terminal BE) connected to it, and the second insulating film (insulating films 107a to 107c, etc.) has a second opening (opening 106a) that, in a plan view with respect to the fourth electrode (second electrode 106), exposes the other side of the fourth electrode (second electrode 106) without being covered by the second insulating film (insulating films 107a to 107c, etc.) between the fourth terminal and the fifth terminal (first terminal TE1 and second terminal TE2), and the first detection circuit (detection circuit 200) has a first measurement circuit (ammeters 230 and 231, respectively) that measures a first resistance value between the first terminal TE1 and the second terminal TE2, and a second resistance value between at least one of the fourth terminal and the fifth terminal (first terminal TE1 and second terminal TE2) and the sixth terminal (third terminal BE).

[0068] This allows for the selective use of hydrogen sensors 100a and 100b, which are microstructures that can be manufactured in the semiconductor manufacturing process, thereby detecting both low and high concentrations of hydrogen. As a result, compared to conventional systems, valves for switching gas flow paths are unnecessary, and a compact, wide-range hydrogen detection device 10b capable of detecting both low and high concentrations of hydrogen is realized.

[0069] Furthermore, the first detection circuit (detection circuit 200) also includes a first control circuit (control circuit 210) that selectively outputs either a first resistance value or a second resistance value.

[0070] Furthermore, the first control circuit (control circuit 210) selectively outputs the first resistance value and the second resistance value based on the first resistance value. As a result, the appropriate hydrogen sensor 100a or 100b is dynamically selected according to the actual hydrogen concentration, and hydrogen detection is performed within the appropriate measurement range.

[0071] Furthermore, the system includes a first switching circuit (switching circuits 20a to 20c) that selectively connects either the first hydrogen sensor (hydrogen sensor 100a for horizontal mode only) or the second hydrogen sensor (hydrogen sensor 100b for vertical mode only) to the first detection circuit (detection circuit 200). This allows for the selective switching of the two types of hydrogen sensors 100a and 100b to the detection circuit 200, thereby enabling the detection of both low and high concentrations of hydrogen.

[0072] Figure 9 is a block diagram showing an example configuration of the hydrogen detection device 10c according to a third modified embodiment. The hydrogen detection device 10c according to this modified embodiment has a configuration in which a spare hydrogen sensor is added to the hydrogen detection device 10b according to the second modified embodiment. More specifically, the hydrogen detection device 10c has the configuration of the hydrogen detection device 10b according to the second modified embodiment, plus a spare hydrogen sensor 110a for horizontal mode, a spare hydrogen sensor 110b for vertical mode, and three switching circuits 21a to 21c.

[0073] The auxiliary hydrogen sensor 110a, which is exclusively for horizontal mode, is an auxiliary hydrogen sensor having the same structure as the auxiliary hydrogen sensor 100a, which is exclusively for horizontal mode.

[0074] The auxiliary hydrogen sensor 110b, which is exclusively for vertical mode, is an auxiliary hydrogen sensor having the same structure as the auxiliary hydrogen sensor 100b, which is exclusively for vertical mode.

[0075] The three switching circuits 21a to 21c are all switches composed of two single-pole double-throw (SPDT) switches. Switching circuit 21a switches the conduction / non-conduction between the detection circuit 200 and the first terminal TE1 and second terminal TE2 of the auxiliary hydrogen sensor 110a, which is dedicated to horizontal mode, under the control of the control circuit 210 of the detection circuit 200. Switching circuit 21b switches the conduction / non-conduction between the detection circuit 200 and the first terminal TE1 and second terminal TE2 of the auxiliary hydrogen sensor 110b, which is dedicated to vertical mode, under the control of the control circuit 210 of the detection circuit 200. Switching circuit 21c switches the conduction / non-conduction between the detection circuit 200 and the third terminal BE of the auxiliary hydrogen sensor 110a, which is dedicated to horizontal mode, and the third terminal BE of the auxiliary hydrogen sensor 110b, which is dedicated to vertical mode, under the control of the control circuit 210 of the detection circuit 200.

[0076] In the hydrogen detection device 10c according to the third modified example, two auxiliary hydrogen sensors 110a and 110b are provided, but only one auxiliary hydrogen sensor may be provided. By selectively using one auxiliary hydrogen sensor in horizontal mode and vertical mode, it can function as either an auxiliary hydrogen sensor for horizontal mode 100a or a auxiliary hydrogen sensor for vertical mode 100b.

[0077] Thus, the hydrogen detection device 10c according to the third modified example comprises a backup hydrogen sensor (at least one of backup hydrogen sensors 110a and 110b) having the same structure as the first hydrogen sensor (hydrogen sensor 100a for horizontal mode only) or the second hydrogen sensor (hydrogen sensor 100b for vertical mode only), and a second switching circuit (switching circuits 21a to 21c) that selectively connects either the first hydrogen sensor (hydrogen sensor 100a for horizontal mode only) and the backup hydrogen sensor (at least one of backup hydrogen sensors 110a and 110b), or either the second hydrogen sensor (hydrogen sensor 100b for vertical mode only) and the backup hydrogen sensor (at least one of backup hydrogen sensors 110a and 110b) to the first detection circuit (detection circuit 200).

[0078] As a result, even if the hydrogen sensor 100a, which is dedicated to the horizontal mode, or the hydrogen sensor 100b, which is dedicated to the vertical mode, fails, hydrogen detection can be continued using at least one of the backup hydrogen sensors 110a and 110b, thereby improving the reliability of the operation of the wide-range hydrogen detection device 10c, which can detect both low and high concentrations of hydrogen.

[0079] Figure 10 is a block diagram showing an example configuration of a hydrogen detection device 10d according to a fourth modified embodiment. The hydrogen detection device 10d according to this modified embodiment includes two bridge circuits, each containing a hydrogen sensor. More specifically, the hydrogen detection device 10d includes a first bridge circuit 120a and a second bridge circuit 120b, each composed of four resistive elements, two switching circuits 22a and 22b, and a detection circuit 200a connected to the first bridge circuit 120a and the second bridge circuit 120b via the switching circuits 22a and 22b.

[0080] The first bridge circuit 120a is a circuit for detecting low concentrations of hydrogen, and consists of a total of four resistive elements connected in a bridge configuration: two resistors R1a and R2a, one hydrogen sensor 100c dedicated to lateral mode, and one resistive element 100d having substantially the same structure as the hydrogen sensor. The cross-sectional structure of the resistive element 100d having substantially the same structure as the hydrogen sensor is shown in Figure 11. Figure 11 shows a resistor R100 with a fixed resistance value, and as can be seen from the figure, this resistor R100 corresponds to the hydrogen sensor 100 shown in Figure 1A where the opening 106a is not formed (i.e., the opening 106a is blocked). Therefore, the resistor R100 does not depend on the hydrogen concentration to which it is exposed and has a fixed resistance value. The two resistors R1a and R2a are resistors with a fixed resistance value, for example, 20Ω, made of polysilicon or the like. As shown in Figure 10, a hydrogen sensor 100c and a resistor element 100d, each dedicated to the horizontal mode, are driven in horizontal mode by a voltage VH (1V) applied to the first terminal TE1, a voltage VB (2.0V) applied to the third terminal BE, and the second terminal TE2 is connected to a reference potential (VSS) via resistors R1a and R2a.

[0081] The second bridge circuit 120b is a circuit for detecting high concentrations of hydrogen, and consists of a total of four resistive elements connected in a bridge configuration: two resistors R1b and R2b, one hydrogen sensor 100e dedicated to vertical mode, and one resistive element 100f with substantially the same structure as the hydrogen sensor. The resistive element 100f has the same structure as resistive element 100d as shown in Figure 11. The two resistors R1b and R2b are fixed-resistance resistors made of polysilicon or the like, for example, 10kΩ resistors. As shown in Figure 10, the hydrogen sensor 100e dedicated to vertical mode and the resistive element 100f are driven in vertical mode by applying a voltage VH (2.6V) to the first terminal TE1, a voltage VL (1.8V) to the second terminal TE2, and the resistor R1b and R2b It is connected to the reference potential (VSS) via [a specific device / mechanism].

[0082] The detection circuit 200a includes a voltmeter 240 for measuring a first voltage between two connection points in the first bridge circuit 120a and a second voltage between two connection points in the second bridge circuit 120b.

[0083] Both switching circuits 22a and 22b are single-pole double-throw (SPDT) switches. Under the control of the detection circuit 200a, switching circuit 22a selectively connects either the connection point between the hydrogen sensor 100c (dedicated to horizontal mode) and resistor R1a in the first bridge circuit 120a, or the connection point between the hydrogen sensor 100e (dedicated to vertical mode) and resistor R1b in the second bridge circuit 120b, to one of the input terminals (+ terminal) of the voltmeter 240. Under the control of the detection circuit 200a, switching circuit 22b selectively connects either the connection point between the resistive element 100d and resistor R2a in the first bridge circuit 120a, or the connection point between the resistive element 100f and resistor R2b in the second bridge circuit 120b, to the other input terminal (- terminal) of the voltmeter 240.

[0084] As a result, a divided voltage is generated at each of the two connection points between the first bridge circuit 120a and the voltmeter 240, due to the hydrogen sensor, or a resistor R100 with substantially the same structure as the hydrogen sensor, and resistor R1a or R2a. Therefore, due to the structural similarity between the hydrogen sensor and resistor R100, the factors causing fluctuations in their characteristics are in phase and cancel each other out, ensuring operational stability against temperature fluctuations and external noise. The same applies to the second bridge circuit 120b. That is, a divided voltage is generated at each of the two connection points between the second bridge circuit 120b and the voltmeter 240, due to the hydrogen sensor, or a resistor R100 with substantially the same structure as the hydrogen sensor, and resistor R1b or R2b. Therefore, due to the structural similarity between the hydrogen sensor and resistor R100, the factors causing fluctuations in their characteristics are in phase and cancel each other out, ensuring operational stability against temperature fluctuations and external noise.

[0085] The operation of the hydrogen detection device 10d according to this modified example (control method for the hydrogen detection device 10d) is the same as, for example, the flowchart shown in Figure 5. That is, the detection circuit 200a first controls the switching circuits 22a and 22b to connect the first bridge circuit 120a, which includes a hydrogen sensor 100c and a resistor element 100d dedicated to horizontal mode, to the voltmeter 240, and uses the hydrogen sensor 100c and resistor element 100d dedicated to horizontal mode to detect low concentrations of hydrogen in horizontal mode (S10). If the resistance balance is disrupted because the hydrogen sensor 100c dedicated to horizontal mode detects hydrogen (i.e., if there is a difference in the resistance values ​​of the hydrogen sensor 100c and the resistor element 100d), it is measured as a polarized voltage by the voltmeter 240.

[0086] Here, each time the detection circuit 200a obtains a voltage value (or hydrogen concentration converted from the voltage) from the voltmeter 240, it determines whether that voltage value (or hydrogen concentration) exceeds a threshold (for example, a hydrogen concentration of 1%, or the corresponding voltage value) (S11).

[0087] As a result, if the obtained voltage value (or hydrogen concentration) exceeds a threshold (for example, a hydrogen concentration of 1%, or the corresponding voltage value) (Yes in S11), the detection circuit 200a controls the switching circuits 22a and 22b to switch the bridge circuit connected to the voltmeter 240 from the first bridge circuit 120a, which includes a hydrogen sensor 100c and a resistor element 100d specifically for horizontal mode, to the second bridge circuit 120b, which includes a hydrogen sensor 100e and a resistor element 100f specifically for vertical mode, in order to detect the hydrogen concentration (S12).

[0088] On the other hand, if the obtained voltage value (or hydrogen concentration) does not exceed a threshold (for example, a hydrogen concentration of 1%, or the corresponding voltage value) (No in S11), the detection circuit 200a continues hydrogen detection using the first bridge circuit 120a, which includes a hydrogen sensor 100c and a resistive element 100d specifically for the horizontal mode.

[0089] Thus, the hydrogen detection device 10d according to the fourth modified example comprises a first bridge circuit 120a and a second bridge circuit 120b, each composed of four resistive elements, and a second detection circuit (detection circuit 200a) connected to the first bridge circuit 120a and the second bridge circuit 120b. One of the four resistive elements constituting the first bridge circuit 120a is a first hydrogen sensor (hydrogen sensor 100c for horizontal mode only), and one of the four resistive elements constituting the second bridge circuit 120b is a second hydrogen sensor (hydrogen sensor 100e for vertical mode only). The second detection circuit (detection circuit 200a) has a second measurement circuit (voltmeter 240) that measures a first voltage between two connection points in the first bridge circuit 120a and a second voltage between two connection points in the second bridge circuit 120b.

[0090] As a result, if the resistance balance between the hydrogen sensors 100c and 100e and the resistive elements 100d and 100f that constitute the first bridge circuit 120a and the second bridge circuit 120b is disrupted, or if a difference in resistance value occurs between them and other resistive elements, the voltmeter 240 will sensitively detect the event, thereby realizing a highly sensitive, wide-range hydrogen detection device 10d that can detect both low and high concentrations of hydrogen.

[0091] Furthermore, among the four resistive elements constituting the first bridge circuit 120a, the resistive element 100d corresponding to the first hydrogen sensor 100c in the positional relationship that determines the first voltage has a structure in which the first aperture (aperture 106a) is not formed in the first hydrogen sensor. Also, among the four resistive elements constituting the second bridge circuit 120b, the resistive element 100f corresponding to the second hydrogen sensor 100e in the positional relationship that determines the second voltage has a structure in which the second aperture (aperture 106a) is not formed in the second hydrogen sensor.

[0092] As a result, the four resistive elements constituting the first bridge circuit 120a have the same basic structure, and the resistance balance of the first bridge circuit 120a can be maintained with high precision in an environment where hydrogen is absent, enabling the realization of a highly sensitive hydrogen detection device 10d. Another advantage is that the same manufacturing process can be applied to the four resistive elements, except for the formation of the openings. The same can be said for the second bridge circuit 120b.

[0093] Figure 12 is a block diagram showing an example configuration of a hydrogen detection device 10e according to a fifth modified embodiment. The hydrogen detection device 10e according to this modified embodiment has a configuration in which a spare bridge circuit is added to the hydrogen detection device 10d according to the fourth modified embodiment. More specifically, the hydrogen detection device 10e includes, in addition to the configuration of the hydrogen detection device 10d according to the fourth modified embodiment, two spare bridge circuits (first spare bridge circuit 130a and second spare bridge circuit 130b) and four switching circuits 22c to 22f.

[0094] The first auxiliary bridge circuit 130a has the same configuration as the first bridge circuit 120a. The second auxiliary bridge circuit 130b has the same configuration as the second bridge circuit 120b. Therefore, the first auxiliary bridge circuit 130a includes a first hydrogen sensor 100g and a resistive element 100h having substantially the same structure as the hydrogen sensor. The resistive element 100h has a structure in which the first opening (opening 106a) is not formed in the first hydrogen sensor (i.e., it is a resistor R100). The second auxiliary bridge circuit 130b includes a second hydrogen sensor 100i and a resistive element 100j having substantially the same structure as the hydrogen sensor. The resistive element 100j has a structure in which the second opening (opening 106a) is not formed in the second hydrogen sensor (i.e., it is a resistor R100).

[0095] Both switching circuits 22c and 22d are single-pole double-throw (SPDT) switches. Under the control of the detection circuit 200a, switching circuit 22c selectively connects either the connection point between the hydrogen sensor 100g (dedicated to horizontal mode) and resistor R3a in the first auxiliary bridge circuit 130a, or the connection point between the hydrogen sensor 100i (dedicated to vertical mode) and resistor R3b in the second auxiliary bridge circuit 130b, to one of the input terminals of the voltmeter 240. Under the control of the detection circuit 200a, switching circuit 22d selectively connects either the connection point between the resistive element 100h and resistor R4a in the first auxiliary bridge circuit 130a, or the connection point between the resistive element 100j and resistor R4b in the second auxiliary bridge circuit 130b, to the other input terminal of the voltmeter 240.

[0096] Both switching circuits 22e and 22f are single-pole double-throw (SPDT) switches. Switching circuit 22e, under the control of detection circuit 200a, selectively connects either the second bridge circuit 120b or the second auxiliary bridge circuit 130b to one of the input terminals of the voltmeter 240. Switching circuit 22f, under the control of detection circuit 200a, selectively connects either the first bridge circuit 120a or the first auxiliary bridge circuit 130a to the other of the input terminals of the voltmeter 240.

[0097] The operation example of the hydrogen detection device 10e according to this modified example is the same as the process in Figure 7. In other words, the detection circuit 200a controls the switching circuits 22e and 22f to normally perform low-concentration and high-concentration hydrogen detection using the first bridge circuit 120a and the second bridge circuit 120b. If it is determined that either bridge circuit is not functioning properly, it switches to the corresponding backup bridge circuit and then performs low-concentration and high-concentration hydrogen detection.

[0098] Thus, the hydrogen detection device 10e according to the fifth modified example includes, in addition to the configuration of the hydrogen detection device 10d according to the fourth modified example, a preliminary bridge circuit having the same configuration as the first bridge circuit 120a or the second bridge circuit 120b (in the modified example, a first preliminary bridge circuit 130a having the same configuration as the first bridge circuit 120a, and a second preliminary bridge circuit 130b having the same configuration as the second bridge circuit 120b), and a third switching circuit (switching circuits 22e and 22f) that selectively connects either the first bridge circuit 120a and the first preliminary bridge circuit 130a, or either the second bridge circuit 120b and the second preliminary bridge circuit 130b, to the second detection circuit (detection circuit 200a).

[0099] As a result, even if either the first bridge circuit 120a or the second bridge circuit 120b fails, hydrogen detection can be continued using at least one of the first backup bridge circuit 130a and the second backup bridge circuit 130b, thereby improving the reliability of the operation of the wide-range hydrogen detection device 10e, which can detect both low and high concentrations of hydrogen.

[0100] In the hydrogen detection device 10e according to the fifth modified example, two auxiliary bridge circuits (first auxiliary bridge circuit 130a and second auxiliary bridge circuit 130b) are provided, but only one auxiliary bridge circuit may be provided. Even if only one auxiliary bridge circuit is provided, the reliability of the operation of the hydrogen detection device is improved by functioning as an auxiliary bridge circuit for the corresponding first bridge circuit 120a or second bridge circuit 120b.

[0101] Figure 13A is a block diagram showing an example configuration of a hydrogen detection device 300 according to a sixth modified embodiment. The hydrogen detection device 300 consists of a semiconductor chip 340 and a voltmeter 330. The semiconductor chip 340 has terminals 301 to 304 connected to a fixed potential, a hydrogen sensor 310 which is an example of a first resistive element constituting a bridge circuit, a resistor R1 which is an example of a second resistive element, a reference element 311 which is an example of a third resistive element, a resistor R2 which is an example of a fourth resistive element, and switching circuits 320 to 323. Note that the hydrogen detection device 300 does not necessarily require a voltmeter 330.

[0102] The hydrogen sensor 310 has the same structure as the hydrogen sensor 100 shown in Figure 1A, and comprises a first electrode 103 and a second electrode 106 with their main surfaces facing each other, a first metal oxide layer (metal oxide layer 104) positioned in contact with the main surfaces of the first electrode 103 and the second electrode 106, and a first insulating film (insulating film 107a to 107c, etc.) covering the first electrode 103, the second electrode 106, and the first metal oxide layer (metal oxide layer 104). The first insulating film has an opening (opening 106a) that exposes the other surface of the second electrode 106 facing the main surface without being covered by the first insulating film. Furthermore, the hydrogen sensor 310 has a first terminal TE1, a second terminal TE2, and a third terminal BE.

[0103] The reference element 311 has the same structure as the resistor R100 shown in Figure 11, and corresponds to the hydrogen sensor 100 shown in Figure 1A in which the opening 106a is not formed (i.e., the opening 106a is closed). In other words, the reference element 311 has a third electrode (first electrode 103 in Figure 11) and a fourth electrode (second electrode 106 in Figure 11) whose main surfaces are arranged facing each other, a second metal oxide layer (metal oxide layer 104 in Figure 11) arranged in contact with the main surface of the third electrode (first electrode 103 in Figure 11) and the main surface of the fourth electrode (second electrode 106 in Figure 11), and a second insulating film (insulating films 107a to 107c, etc. in Figure 11) covering the third electrode (first electrode 103 in Figure 11), the fourth electrode (second electrode 106 in Figure 11), and the second metal oxide layer (metal oxide layer 104 in Figure 11). Furthermore, the second insulating film does not have an opening that exposes the other surface facing the main surface of the fourth electrode (the second electrode 106 in Figure 11) without being covered by the second insulating film. In addition, the reference element 311 has a first terminal TE1, a second terminal TE2, and a third terminal BE, similar to the hydrogen sensor 310.

[0104] The two resistors R1 and R2 have the same resistance value and are fixed-resistance resistors made of polysilicon or the like, for example, 20Ω resistors.

[0105] Switching circuits 320 and 321 are connected to the hydrogen sensor 310 This is a switch for switching between horizontal and vertical connection modes. Specifically, it is for the hydrogen sensor 310 When switching to the horizontal mode connection state, the switching circuit 320 is activated by an external control signal, and the hydrogen sensor 310 The second terminal TE2 is connected to resistor R1, and the switching circuit 321 is connected to the hydrogen sensor 310 Connect the third terminal BE to terminal 303. Meanwhile, the hydrogen sensor 310 When switching to the vertical mode connection state, the switching circuit 320 is activated by an external control signal, and the hydrogen sensor 310 The second terminal TE2 is connected to terminal 301, and the switching circuit 321 is connected to the hydrogen sensor 310 Connect the third terminal BE to resistor R1.

[0106] Switching circuits 322 and 323 are switches for switching the connection state of the reference element 311 between horizontal mode and vertical mode. Specifically, when the reference element 311 is connected in horizontal mode, an external control signal causes switching circuit 322 to connect the second terminal TE2 of the reference element 311 to resistor R2, and switching circuit 323 to connect the third terminal BE of the reference element 311 to terminal 303. On the other hand, when the reference element 311 is connected in vertical mode, an external control signal causes switching circuit 322 to connect the second terminal TE2 of the reference element 311 to terminal 301, and switching circuit 323 to connect the third terminal BE of the reference element 311 to resistor R2.

[0107] Figure 13B is an equivalent circuit diagram of the hydrogen detection device 300 shown in Figure 13A. For ease of understanding, an external DC voltage source 331, which is not shown in Figure 13A, is also shown here. The equivalent circuit diagram shown in this figure is applicable to both cases: when the hydrogen sensor 310 and the reference element 311 are connected in a horizontal mode to detect low concentrations of hydrogen, and when the hydrogen sensor 310 and the reference element 311 are connected in a vertical mode to detect high concentrations of hydrogen.

[0108] Basically, when the hydrogen sensor 310 is used in horizontal mode, the reference element 311 is also used in horizontal mode, while when the hydrogen sensor 310 is used in vertical mode, the reference element 311 is also used in vertical mode.

[0109] As described above, the hydrogen sensor 310 and the reference element 311 have basically the same structure and have the same resistance value in an environment where hydrogen is absent. Resistors R1 and R2 have fixed resistance values. In an environment where hydrogen is present, only the resistance value of the hydrogen sensor 310 changes, creating a difference in resistance between the hydrogen sensor 310 and the reference element 311. As a result, a difference in potential occurs between the connection point between the hydrogen sensor 310 and resistor R1 and the connection point between the reference element 311 and resistor R2, and this potential difference is measured by the voltmeter 330.

[0110] Thus, the hydrogen detection device 300 according to this modified example is composed of a bridge circuit and switching circuits 320-323 including a hydrogen sensor, thereby realizing a highly sensitive, wide-range hydrogen detection device that can detect both low and high concentrations of hydrogen.

[0111] Furthermore, since the hydrogen sensor 310, reference element 311, and resistors R1 and R2 that constitute the bridge circuit are formed on a single semiconductor chip 340 using the same semiconductor manufacturing process, the hydrogen detection device 300 can be made smaller compared to the case where these components are mounted on a printed circuit board.

[0112] In the hydrogen detection device 300 according to this modified example, the hydrogen sensor 310 and the reference element 311 were selectively switchable between horizontal and vertical modes. However, such switchability is not necessarily required, and they may be fixed to one of the modes. Therefore, the hydrogen sensor 310 and the reference element 311 do not necessarily need to be provided with three terminals (first terminal TE1, second terminal TE2, and third terminal BE), and may be provided with only two terminals.

[0113] Furthermore, in the hydrogen detection device 300 according to this modified example, the hydrogen sensor 310, reference element 311, and resistors R1 and R2 are formed on a single semiconductor chip 340. However, it is also possible that only the hydrogen sensor 310 and reference element 311 among these four resistive elements are formed on a single semiconductor chip 340. In either configuration, the hydrogen sensor 310 and reference element 311 have the same basic structure and constitute a bridge circuit, thus achieving highly sensitive hydrogen detection.

[0114] The hydrogen detection device and control method for the hydrogen detection device described herein have been explained above based on embodiments and modifications, but this disclosure is not limited to these embodiments and modifications. Within the scope of this disclosure, various modifications conceivable by those skilled in the art, as well as other forms constructed by combining some of the components of the embodiments and modifications, are also included, as long as they do not depart from the spirit of this disclosure.

[0115] For example, in the hydrogen detection device 10 according to this embodiment, the detection circuit 200 is equipped with two ammeters 230 and 231, but the configuration is not limited to this, and it may be equipped with one ammeter and used by switching between horizontal mode and vertical mode.

[0116] Furthermore, in the hydrogen detection device 10 according to this embodiment, the detection circuit 200 is equipped with a function to operate based on an external instruction CMD1, but an external instruction CMD1 is not necessarily required. As shown in the flowchart of Figure 5, it may operate in a fixed processing flow such as always operating in horizontal mode and switching to vertical mode when the hydrogen concentration exceeds a threshold.

[0117] Furthermore, in the hydrogen detection device 10 according to the embodiment, in horizontal mode, current flows from the first terminal TE1 to the second terminal TE2, but the direction of current flow may be reversed.

[0118] Furthermore, although the hydrogen detection device 10 according to the embodiment was always driven in horizontal mode, the drive configuration is not limited to this, and the drive may be switched between horizontal mode and vertical mode in a time-division manner.

[0119] Furthermore, in the hydrogen detection device 10a etc. according to the first modified example, the switching circuits 20a to 20c were double-throw switches that connected the terminals of the hydrogen sensor to either the detection circuit 200 or ground, but they may also be simply single-throw switches that either connect or disconnect the terminals of the hydrogen sensor to the detection circuit 200 (ON / OFF type).

[0120] Furthermore, in the hydrogen detection device 10d according to the fourth modified example, the detection circuit 200a is equipped with one voltmeter 240 and is selectively connected to either the first bridge circuit 120a or the second bridge circuit 120b. However, the configuration is not limited to this, and a total of two voltmeters may be provided, one connected to the first bridge circuit 120a and the other connected to the second bridge circuit 120b.

[0121] Furthermore, in the hydrogen detection device 10e according to the fifth modified example, two auxiliary bridge circuits (first auxiliary bridge circuit 130a and second auxiliary bridge circuit 130b) are provided. However, instead of these, or in addition to them, as in the first and third modified examples, at least one auxiliary hydrogen sensor may be provided to replace the hydrogen sensor 100c and resistor element 100d, which are dedicated to the horizontal mode and constitute the first bridge circuit 120a, or at least one auxiliary hydrogen sensor may be provided to replace the hydrogen sensor 100e and resistor element 100f, which are dedicated to the vertical mode and constitute the second bridge circuit 120b. [Industrial applicability]

[0122] The hydrogen detection device described herein can be used, for example, as a hydrogen detection device mounted in a fuel cell vehicle, as a compact and wide-range hydrogen detection device capable of detecting both low and high concentrations of hydrogen. [Explanation of symbols]

[0123] 10, 10a~10e Hydrogen detection device 20a~20c, 21a~21c, 22a~22f switching circuit 100, 100a~100c, 100e, 100g, 100i Hydrogen Sensor 100d, 100f, 100h, 100j resistors 102 Insulating film 103 1st electrode 104 Metal oxide layer 104a 1st layer 104b 2nd layer 104i Insulation Separation Layer 106 2nd electrode 106a, TE1a, TE2a, BEa opening 106e Exposed part 106s metal layer 107a, 107b, 107c, 109a, 109b insulating film 108 Beer 110, 110a, 110b Backup hydrogen sensors 114 Wiring 120a First Bridge Circuit 120b Second Bridge Circuit 130a First Auxiliary Bridge Circuit 130b Second Auxiliary Bridge Circuit 200, 200a detection circuit 210 Control circuit 220 Drive Circuit 230, 231 ammeter 240 Voltmeter 300 Hydrogen detection device Terminals 301-304 310 Hydrogen Sensor 311 Reference element 320~323 Switching Circuit 330 Voltmeter 331 DC voltage source 340 semiconductor chips TE1 First terminal TE2 Second terminal BE Terminal 3 R1, R2, R1a, R1b, R2a, R2b, R3a, R3b, R4a, R4b, R100 Resistance

Claims

1. A first hydrogen sensor and a second hydrogen sensor for detecting hydrogen, The system comprises a first hydrogen sensor and a first detection circuit connected to the second hydrogen sensor, The first hydrogen sensor is, A first electrode and a second electrode are arranged with their main surfaces facing each other, A first metal oxide layer is disposed in contact with the main surface of the first electrode and the main surface of the second electrode, The first electrode, the second electrode, and the first insulating film covering the first metal oxide layer, The first terminal and the second terminal are connected via vias to the other surface of the second electrode facing the main surface, The first electrode has a third terminal connected via a via to the other surface facing the main surface of the first electrode, The first insulating film has a first opening between the first terminal and the second terminal in a plan view with respect to the second electrode, which exposes the other side of the second electrode without being covered by the first insulating film. The second hydrogen sensor is, The third electrode and the fourth electrode are arranged with their main surfaces facing each other, A second metal oxide layer is disposed in contact with the main surface of the third electrode and the main surface of the fourth electrode, The third electrode, the fourth electrode, and the second insulating film covering the second metal oxide layer, A fourth terminal and a fifth terminal connected via vias to the other surface of the fourth electrode facing the main surface, The third electrode has a sixth terminal connected via a via to the other surface facing the main surface of the third electrode, The second insulating film has a second opening between the fourth terminal and the fifth terminal in a plan view with respect to the fourth electrode, which exposes the other side of the fourth electrode without being covered by the second insulating film. The first detection circuit is, The device has a first measuring circuit for measuring a first resistance value between the first terminal and the second terminal, and a second resistance value between at least one of the fourth terminal and the fifth terminal and the sixth terminal. Hydrogen detection device.

2. The first detection circuit further includes a first control circuit that selectively outputs either the first resistance value or the second resistance value. The hydrogen detection device according to claim 1.

3. The first control circuit selectively outputs the first resistance value and the second resistance value based on the first resistance value. The hydrogen detection device according to claim 2.

4. Furthermore, it includes a first switching circuit that selectively connects either the first hydrogen sensor or the second hydrogen sensor to the first detection circuit. The hydrogen detection device according to claim 1.

5. moreover, A backup hydrogen sensor having the same structure as the first hydrogen sensor or the second hydrogen sensor, The system includes a second switching circuit that selectively connects either the first hydrogen sensor or the reserve hydrogen sensor, or either the second hydrogen sensor or the reserve hydrogen sensor, to the first detection circuit. The hydrogen detection device according to claim 1.

6. A first bridge circuit and a second bridge circuit, each composed of four resistive elements, The system comprises the first bridge circuit and a second detection circuit connected to the second bridge circuit, One of the four resistive elements constituting the first bridge circuit is the first hydrogen sensor according to claim 1. One of the four resistive elements constituting the second bridge circuit is the second hydrogen sensor according to claim 1. The second detection circuit includes a second measurement circuit that measures a first voltage between two connection points in the first bridge circuit and a second voltage between two connection points in the second bridge circuit. Hydrogen detection device.

7. Of the four resistive elements constituting the first bridge circuit, the resistive element corresponding to the first hydrogen sensor in the positional relationship that determines the first voltage has a structure in which the first opening is not formed in the first hydrogen sensor. Of the four resistive elements constituting the second bridge circuit, the resistive element corresponding to the second hydrogen sensor in the positional relationship that determines the second voltage has a structure in which the second aperture is not formed in the second hydrogen sensor. The hydrogen detection device according to claim 6.

8. moreover, A backup bridge circuit having the same configuration as the first bridge circuit or the second bridge circuit, The system includes a third switching circuit that selectively connects either the first bridge circuit or the auxiliary bridge circuit, or either the second bridge circuit or the auxiliary bridge circuit, to the second detection circuit. The hydrogen detection device according to claim 6.

9. The first hydrogen sensor detects lower concentrations of hydrogen compared to the second hydrogen sensor. A hydrogen detection device according to any one of claims 1 to 8.

10. The first metal oxide layer and the second metal oxide layer are composed of transition metal oxides. A hydrogen detection device according to any one of claims 1 to 8.

11. The first electrode and the third electrode are made of transition metal nitride. The second electrode and the fourth electrode are made of a precious metal. A hydrogen detection device according to any one of claims 1 to 8.

12. A first hydrogen sensor that detects hydrogen, The system comprises a third detection circuit connected to the first hydrogen sensor, The first hydrogen sensor is, A first electrode and a second electrode are arranged with their main surfaces facing each other, A first metal oxide layer is disposed in contact with the main surface of the first electrode and the main surface of the second electrode, The first electrode, the second electrode, and the first insulating film covering the first metal oxide layer, The first terminal and the second terminal are connected via vias to the other surface of the second electrode facing the main surface, The first electrode has a third terminal connected via a via to the other surface facing the main surface of the first electrode, The first insulating film has a first opening between the first terminal and the second terminal in a plan view with respect to the second electrode, which exposes the other side of the second electrode without being covered by the first insulating film. The third detection circuit is, A third measuring circuit for measuring a first resistance value between the first terminal and the second terminal, and a second resistance value between at least one of the first terminal and the second terminal and the third terminal, The device includes a second control circuit that selectively outputs either the first resistance value or the second resistance value. Hydrogen detection device.

13. The second control circuit selectively outputs either the first resistance value or the second resistance value based on the first resistance value. The hydrogen detection device according to claim 12.

14. moreover, A backup hydrogen sensor having the same structure as the first hydrogen sensor, The system includes a third switching circuit that selectively connects either the first hydrogen sensor or the reserve hydrogen sensor to the third detection circuit. The hydrogen detection device according to claim 12.

15. The first resistance value is more dependent on low concentrations of hydrogen than the second resistance value. The hydrogen detection device according to claim 12.

16. The first metal oxide layer is composed of a transition metal oxide. The hydrogen detection device according to claim 12.

17. The first electrode is made of a transition metal nitride. The aforementioned second electrode is made of a precious metal. A hydrogen detection device according to any one of claims 12 to 16.

18. It comprises a first resistive element, a second resistive element, a third resistive element, and a fourth resistive element that constitute a bridge circuit, One end of the first resistive element and one end of the second resistive element are connected. One end of the third resistive element and one end of the fourth resistive element are connected. The other end of the first resistive element and the other end of the third resistive element are connected. The other end of the second resistive element and the other end of the fourth resistive element are connected. The first resistive element is a hydrogen sensor, A first electrode and a second electrode are arranged with their main surfaces facing each other, A first metal oxide layer is disposed in contact with the main surface of the first electrode and the main surface of the second electrode, The device comprises the first electrode, the second electrode, and a first insulating film covering the first metal oxide layer, The first insulating film has an opening that exposes the other surface of the second electrode facing the main surface without being covered by the first insulating film. The third resistor is a reference element, The third electrode and the fourth electrode are arranged with their main surfaces facing each other, A second metal oxide layer is disposed in contact with the main surface of the third electrode and the main surface of the fourth electrode, The device comprises the third electrode, the fourth electrode, and a second insulating film covering the second metal oxide layer, The second insulating film does not have an opening that exposes the other surface of the fourth electrode facing the main surface without being covered by the second insulating film. Hydrogen detection device.

19. The first resistive element has a first terminal and a second terminal connected via vias to the other side of the second electrode, with one end and the other end of the first resistive element being the first terminal and the other end of the second resistive element. The opening is formed between the first terminal and the second terminal in a plan view with respect to the second electrode. The hydrogen detection device according to claim 18.

20. The first resistive element has, as one end and the other end of the first resistive element, a terminal connected via a via to the other surface of the second electrode and a third terminal connected via a via to the other surface of the first electrode facing the main surface. The hydrogen detection device according to claim 18.

21. Of the first resistive element, the second resistive element, the third resistive element, and the fourth resistive element, at least the first resistive element and the third resistive element are formed on a single semiconductor chip. A hydrogen detection device according to any one of claims 18 to 20.

22. The first resistive element, the second resistive element, the third resistive element, and the fourth resistive element are formed on the single semiconductor chip. The hydrogen detection device according to claim 21.

23. A control method for a hydrogen detection device according to claim 1, The first detection circuit is, The first resistance value is obtained, Based on the acquired first resistance value, either the first resistance value or the second resistance value is selectively output. Control method.

24. A control method for a hydrogen detection device according to claim 6, The second detection circuit is, The first voltage is obtained, Based on the acquired first voltage, either the first voltage or the second voltage is selectively output. Control method.

25. A control method for a hydrogen detection device according to claim 12, The third detection circuit is, The first resistance value is obtained, Based on the acquired first resistance value, either the first resistance value or the second resistance value is selectively output. Control method.

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