JPH07260729A - Board-type semiconductor gas sensor and gas detector - Google Patents

Abstract

PURPOSE:To obtain a gas sensor wherein odor measurement can be exactly performed in a lower concentration area by heightening sensitivity for various odors of a detection object, the improving an S/N ratio by lowering the sensitivity for odorless gas. CONSTITUTION:In a board-type semiconductor gas sensor 1 wherein a metal oxide semiconductor film layer, 3 having tin oxide as a main component is provided on a board 2, and a detection electrode 4 electrically connected to the metal oxide semiconductor film layer 3 is provided, an average primary particle diameter of tin oxide is from 35 to 70nm, the film thickness of the metal oxide semiconductor film layer is from 10 to 50mum, a kind or more of either of lead or lanthanum are added to the metal oxide semiconductor film layer 3, and a coating layer 8 of various metal oxides is provided on a surface layer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention, when it is necessary to check the strength and presence of odor, for example, confirmation of the effect of a deodorant, control of flavors used in the food industry, confirmation of the presence or absence of odor in food packaging materials, The present invention relates to a technique used for environmental measurement in the vicinity of a factory that produces odors, and more specifically, a metal mainly composed of tin oxide on a substrate used for detecting such odor gas. A substrate type semiconductor gas sensor including an oxide semiconductor film layer and a detection electrode electrically connected to the metal oxide semiconductor film layer, and a sensor of this type, and detecting the sensor temperature appropriately. The present invention relates to a gas detector equipped with heating means for maintaining the temperature.

[0002]

2. Description of the Related Art Up to now, odor evaluation has been conducted by a sensory test method or an instrumental analysis method using gas chromatography or the like.
However, the former has problems that the test method is complicated, at least three or more people are required, and the obtained result is not objective. The latter also has the problems that the equipment and its maintenance cost are expensive, a high degree of knowledge is required to operate the equipment, and it takes a long time for measurement. Therefore,
Recently, as a simple odor evaluation method, a method using a semiconductor odor sensor with high sensitivity to odorous gas is being used. Then, in the substrate type semiconductor gas sensor targeted by the present application, tin oxide as a gas sensitive material is fired at a temperature of 600 ° C. to 800 ° C., and the average primary particle diameter thereof is set to 20 to 30 nm to obtain a specific surface area. Was set to a relatively high level of about 7 to ²⁰ m ² / g. And
For gas detection, the sensor temperature was set to about 350 ° C. to detect gas.

[0003]

The above-mentioned prior art has the following drawbacks. That is, in the conventional semiconductor type (using tin oxide burned at 600 to 800 ° C.) odor sensor, the limit of the gas concentration that can be detected by the sensor (the lower limit of detection) and the limit at which humans sense the odor There is a large gap between the concentrations (detection thresholds) of
I can't confirm enough odor. Furthermore, in the conventional substrate type semiconductor gas sensor, for gases having an odor such as alcohols, ketones, and aldehydes,
Odorless gases such as hydrogen, isobutane and carbon monoxide are difficult to identify and detect. Further, it is difficult to distinguish and detect these even between gases having an odor. On the other hand, the disadvantages due to the firing temperature (primary particle size) of tin oxide are that the sensor does not have long-term stability, high humidity dependency, high film thickness dependency, unstable quality and poor yield. I had a problem with.
Therefore, an object of the present invention is to improve the S / N ratio by increasing the sensitivity to various odors to be detected and reducing the sensitivity to odorless gas, and to accurately measure the odor in a lower concentration range. It is an object of the present invention to obtain a gas sensor that can be performed and solves the above problems caused by a low firing temperature.

[0004]

In order to achieve this object, a metal oxide semiconductor film layer containing tin oxide as a main component is provided on a substrate according to the first invention of the present application, and the metal oxide semiconductor film layer is electrically connected to the substrate. The characteristic configuration of the substrate-type semiconductor gas sensor configured to include the detection electrode connected to is that tin oxide has an average primary particle diameter of 35 nm to 70 nm, and the metal oxide semiconductor film layer has a thickness of 10 μm to 50 μm. Which is formed by adding at least one of lead (Pb) and lanthanum (La) to the metal oxide semiconductor film layer, and the characteristic configuration of the gas detector including the substrate type semiconductor gas sensor is , Which forms the metal oxide semiconductor film layer 450
There is a heating means for heating and maintaining the temperature from ℃ to 550 ℃. A substrate-type semiconductor device including a metal oxide semiconductor film layer containing tin oxide as a main component on a substrate according to the second invention of the present application, and a detection electrode electrically connected to the metal oxide semiconductor film layer The characteristic configuration of the gas sensor is that the average primary particle diameter of tin oxide is 35 nm to 70 nm, the thickness of the metal oxide semiconductor film layer is 10 μm to 50 μm, and lead (Pb) or At least one of lanthanum (La) is added,
On the surface layer of the metal oxide semiconductor film layer, tungsten oxide (WO
₃ ) or molybdenum oxide (MoO ₃ ) coating layer. The characteristic configuration of the gas detector provided with this substrate type semiconductor gas sensor is that it is provided with heating means for heating and maintaining the metal oxide semiconductor film layer at 450 ° C. to 550 ° C. A metal oxide semiconductor film layer containing tin oxide as a main component on a substrate according to the third invention of the present application;
The characteristic configuration of the substrate-type semiconductor gas sensor configured to include the detection electrode electrically connected to the metal oxide semiconductor film layer is that the average primary particle diameter of tin oxide is 35 nm to 70 nm.
And at least one of lead (Pb) and lanthanum (La) is added to the metal oxide semiconductor film layer, and the thickness of the metal oxide semiconductor film layer is 10 μm to 50 μm.
The metal oxide semiconductor film layer has a coating layer of zinc oxide (ZnO) or titanium oxide (TiO ₂ ) formed on the surface of the metal oxide semiconductor film layer. The gas detector equipped with the substrate type semiconductor gas sensor is characterized in that it comprises a heating means for heating and maintaining the metal oxide semiconductor film layer at 450 ° C. to 550 ° C. Their actions and effects are as follows.

[0005]

In other words, in the substrate type semiconductor gas sensor of the present application, the average primary particle diameter of tin oxide forming the metal oxide semiconductor film layer is set in a specific range in both the first, second and third inventions. It When controlling the average primary particle diameter of tin oxide, one of the most common methods is to control the firing temperature. FIG. 2 shows the relationship between the sintering temperature of tin oxide and the average primary particle size or specific surface area. As shown in the figure, the conventional sensor is
By firing at 800 ° C., the average primary particle size is 20 to
The specific surface area is set to 7 to ²⁰ m ² / g at 30 nm, and in the present invention, 1000 to 1400.
By calcination at ℃, the average primary particle size is 35 ~
The specific surface area is 4.5 to 1.8 m ² / g at 70 nm. And the sensor formed in this way is
The film thickness (which means the thickness from the surface of the electrode to the surface of the metal oxide semiconductor) makes it sensitive to odorous gases such as alcohols, ketones and aldehydes.
This situation will be described with reference to FIG. FIG. 4 shows the dependence of sensitivity on the film thickness, and the solid line shows the sensor of the present invention having a large average primary particle diameter (the actual sensor is 53 nm). As shown in the figure, when the film thickness is 10 to 50 μm, the gas can be detected with a selectivity for hydrogen with respect to ethanol, which can represent the odor gas. Therefore,
By properly selecting the average primary particle size of tin oxide and the film thickness of the tin oxide of the substrate type semiconductor gas sensor, the odor gas can be effectively identified and detected. Here, in the above description, the temperature of the film layer in the gas detection state was not described (in the above description, it was described in the good sensitivity range), but for each detection target gas with respect to the sensor temperature The temperature sensitivity state is shown in FIG. 5A shows the temperature dependence of the sensitivity of the sensor of the present application, and FIG. 5B shows the temperature dependence of the sensitivity of the conventional sensor. As can be seen from the comparison of both figures, in the sensor of the present application, the temperature range in which the sensitivity is relatively high is 450 ° C. to 550 ° C.
It is less than 350 ° C. Therefore, in the gas detector of the present application,
A heating means is provided, and the sensor is configured to perform gas detection in the temperature range where the sensitivity is highest.

[0006] The above is the first, by properly selecting the primary particle diameter, the film thickness, and the temperature of the gas-sensitive material.
In addition to the above-mentioned common points, in the sensor of the first invention, one or both of lead and lanthanum are added to the gas-sensitive material, which is the effect obtained by the second and third inventions. Table 1 shows the changes in sensitivity with the addition of these elements for various gases. At this time, the addition amount of “La addition” in Table 1 is 2 atm%, the addition amount of “Pb addition” is 2 atm%, and the addition amount of “La + Pb addition” is 2 atm, respectively.
It is atm%.

[0007]

[Table 1] Addition of these elements generally leads to a decrease in sensitivity,
In this case, comparing the rate of decrease in sensitivity to hydrogen and isobutane with the rate of decrease in sensitivity to alcohol,
The former is considerably larger, and as shown in FIGS. 8 and 9, generally, in a sensor having the configuration of the present application, these gases are noises for detection, and as a result, these gases are detected. The reduced sensitivity to gas allows odorous gas (typified by ethanol) to be discriminated and detected against interfering gases such as hydrogen and isobutane. Now, the addition amount of these elements is appropriately 0.5 to 8 atm% with respect to tin oxide, and if it is less than this range, there is no effect. Above this, the sensitivity to odorous gas decreases.

Further, the second gas sensor of the present invention has the sensor structure of the first invention, and is provided with a coating layer of tungsten oxide (WO ₃ ) or molybdenum oxide (MoO ₃ ) on the surface thereof. Further, by providing such a layer, as shown in FIGS. 12 and 13, it is possible to obtain one having a particularly high sensitivity to propionic acid and styrene. When the tungsten oxide (WO ₃ ) coating layer is provided, high sensitivity is obtained not only for the above two gases but also for methyl sulfide and trimethylamine. On the other hand, when a coating layer of molybdenum oxide (MoO ₃ ) is provided, in addition to the above two types of gas,
It has high sensitivity to hydrogen sulfide, methyl mercaptan, and trimethylamine. A suitable layer thickness of these coating layers is about 10 to 100 .mu.m. If the thickness exceeds this range, the sensitivity decreases and the response speed slows down. As it becomes thinner, it loses its effect. Further, the third gas sensor of the present invention has the sensor structure of the first invention, and has a coating layer of zinc oxide (ZnO) or titanium oxide (TiO ₂ ) on the surface thereof.
And, by providing such a layer,
As shown in 1, it is possible to obtain a particularly sensitive one for ethanol, acetaldehyde, acetone, propionic acid, and ethyl acetate. A suitable layer thickness of these coating layers is about 10 to 100 .mu.m, and if the thickness exceeds this range, the sensitivity decreases and the response speed slows down. As it becomes thinner, it loses its effect.

[0009]

As described above, the sensitivity to various odors to be detected is increased, and the sensitivity to odorless gas is reduced to improve the S / N ratio, and the odor can be accurately measured in a lower concentration range. A gas sensor could be obtained.
Further, in such a sensor in which the average primary particle diameter of tin oxide is manipulated, the sensitivity is stable for a long time, the humidity dependency is low, the film thickness dependency is low, and a stable quality sensor can be obtained in good yield. You can

[0010]

Embodiments of the present application will be described with reference to the drawings. 1 Structure of Gas Sensor and Gas Detector FIG. 1 shows the configuration of a substrate type semiconductor gas sensor 1 of the present application. As shown in the figure, the sensor 1 includes a metal oxide semiconductor film layer 3 containing tin oxide as a main component on an alumina substrate 2, and is electrically connected to the metal oxide semiconductor film layer 3. The platinum thin film electrode 4 as a detection electrode is provided. Then, with respect to the platinum thin film electrode 4, a detection side circuit is assembled so as to detect a change in the resistance value between the electrodes, and the detection means 5 is configured. A general example of this detection-side circuit is a circuit that includes a load resistor RL connected in series with the sensor 1 and obtains a voltage output at this resistor. Further, a platinum thin film heater 6 is provided on the back surface side of the alumina substrate 2, and a sensor temperature control device 7 is connected to the platinum thin film heater 6 to constitute heating means. This heating means heats and maintains the sensor (metal oxide semiconductor film layer) 1 at 450 to 550 ° C. which is a sensor temperature suitable for the operation of the sensor of the present application. Further, as described below, a coating layer 8 is provided on the sensor surface for the purpose of increasing the sensitivity to a specific gas. By adopting the above configuration, the gas detector 100 is configured as a whole.

The requirements of the substrate type semiconductor gas sensor of the present application will be described below. Odor gas sensor Average primary particle size of tin oxide 35 to 70 nm Firing temperature 1000 to 1400 ° C Specific surface area 4.5 to 1.8 m ² / g Metal oxide semiconductor film thickness 10 to 50 µm Operating temperature for gas detection 450 to 550 ° C Lead , Lanthanum addition ratio 0.5 to 8 atm% Layer thickness of each coating layer 10 to 100 μm

2 Method for manufacturing sensor A fixed aqueous solution was prepared using tin tetrachloride, and a tin hydroxide precipitate obtained by adding ammonia water dropwise thereto was dried and then calcined in an electric furnace at 600 ° C. for 2 hours. To obtain tin oxide. This is crushed into a fine powder and kneaded with water to form a paste.
This paste is applied to the electrode portion of the alumina substrate 2 having the platinum thin film comb-shaped electrode 4 and the heater 6. After drying this, it is baked at a temperature of 1000 ° C. to 1400 ° C. for 2 hours in an electric furnace (not shown) to obtain a thick film of tin oxide, and the gas sensor 1 is obtained. The addition of lead (Pb) is lead nitrate, lanthanum (L
The addition of a) is performed by adding an aqueous solution of lanthanum nitrate to the above tin oxide in the range of 0.5 to 8 atm% for lead (the optimum addition amount is 2
atm%), and in the case of lanthanum, 0.5 to 8 atm% (optimum addition amount of 2 atm%) is adjusted to impregnate each liquid into the sintered body. After further drying this at room temperature, 60
It heats at 0 degreeC for 1 hour, and each oxide is obtained. Next, each of zinc oxide, titanium oxide, tungsten oxide, and molybdenum oxide is pulverized into a fine powder, which is kneaded with water to form a paste, which is applied to the surface layer of the tin oxide sintered body. Further, after drying at room temperature, it is heated at 600 ° C. for 2 hours and sintered to form a coating layer.

3 Sensor Sensitivity Measurement Method The sensor obtained by the above method is incorporated into an electric circuit as shown in FIG. 1, and the voltage across the load resistor RL connected in series with the electrode terminal of the sensor is measured. , Calculate the resistance value of the sensor from this voltage value. The sensitivity is defined as the ratio of the sensor resistance value (Ra) in clean air and the sensor resistance value (Rg) in gas, that is, Ra / Rg (rate of change in resistance).
In the present application, the sensitivity measurements of FIGS. 3, 4, 5, and 6 are arranged by the above method. Further, FIGS. 7 to 13 show absolute output values (unit: mV).

4 Results of Sensor Characteristics Experiments (1) Dependence of Average Primary Particle Diameter FIG. 3 shows the sensor temperature of 450 ° C.
The average primary particle size dependence of the sensitivity to ethanol and hydrogen at 500 ° C. and 550 ° C. is shown. In this case, in order to confirm the distinguishability of ethanol, the concentration of this gas was set to 100 ppm and the hydrogen gas concentration was set to 10 ppm.
It was set to 00 ppm. The average primary particle size was changed from 10 to 70 nm. In the figure, the solid line shows the change in sensitivity to ethanol, and the dotted line shows the change in sensitivity to hydrogen. As is clear from this figure, the sensitivity to ethanol rapidly increases when the average primary particle size of tin oxide is 40 nm or more. On the other hand, since the sensitivity to hydrogen decreases from the average primary particle diameter of 45 nm or more, it is possible to reduce the hydrogen sensitivity by controlling the average primary particle diameter. Furthermore, when tin oxide having an average primary particle diameter of the sensor of the present application is used as a sensor for an organic solvent gas, the operating temperature is 450 ° C. to 550 ° C., preferably 500 ° C.
It can be seen that the temperature is ° C.

(2) Dependence of film thickness FIG. 4 shows the experimental results regarding this characteristic. As the sensor to be tested, the sensor of the present application (average primary particle size 5
3 nm, sensor temperature 500 ° C.) A conventional sensor with a relatively small particle size (average primary particle size 19 nm, sensor temperature 3)
(50 ° C.). Film thickness is 10μm to 300μ
It was changed to m. In the figure, the solid line shows the sensitivity change with respect to the film thickness of the sensor of the present application (sensitivity to ethanol 100 ppm and hydrogen 1000 ppm), and the dotted line shows the sensitivity change with respect to the film thickness of the conventional sensor (ethanol 100 pp).
m, sensitivity to 1000 ppm of hydrogen).
As can be seen from the figure, the sensor of the present application has a region where the sensitivity is stable in a relatively wide film thickness range, and the film thickness region having a high sensitivity to odor gas and the region having a high sensitivity to hydrogen gas have an alternating characteristic. Have Therefore,
In detecting odorous gas, it is preferable to set the film thickness to 10 to 50 μm. On the other hand, in the conventional sensor, the film thickness dependence of the sensor sensitivity is large (the broken line largely falls), and the sensitivity increase / decrease tendency with respect to the film thickness with respect to the odor gas and the hydrogen gas is similar. Therefore, the conventional type has a large dependency on the film thickness, and further, it is difficult to obtain the selectivity between gases.

(3) Sensor Temperature Dependence FIG. 5 shows the sensor of the present invention, which is suitable for ethanol, acetone (gases having odor), hydrogen, isobutane, carbon monoxide, methane (odorless gas). The sensor temperature dependence of sensitivity was shown. In this case, in order to confirm the distinctiveness of odorous gas, the concentration of these gases should be 100ppm.
Furthermore, the odorless gas concentration was set to 1000 ppm. The sensor temperature was changed from 300 to 550 ° C. Further, FIG. 5A shows the result of the sensor of the present invention in which the average primary particle diameter is set large, and FIG. 5B shows the result of the conventional sensor. As is clear from FIG. 5A, the temperature range in which the sensor of the present application has good sensitivity is the temperature range of 450 to 550 ° C. as shown in FIG. And in this area, it has sufficient distinctiveness with respect to odorless gas. On the other hand, in the conventional sensor, the high sensitivity region is a relatively low temperature region below 350 ° C. In this region, the conventional sensor has low identifiability with respect to odorless gas (especially hydrogen).

(4) Particle size dependency in various gases Corresponding to FIG. 3, the results of examining the average primary particle size dependency of the sensor are shown in FIG. Here, each gas (ethanol,
The concentration of acetone, acetaldehyde, propionic acid, diethyl ether, ethyl acetate) is 100 ppm, which was difficult to detect in the past, and the thickness of the sensor is 10 to 50 μm.
In addition, the sensor temperature is set to 450 to 550 ° C.
As a result, the sensitivity to various gases other than ethanol is also high when the average primary particle size is in the range of 35 nm to 70 nm. Therefore, in order to increase the selectivity between the organic solvent gas and an odorless gas such as hydrogen and increase the sensitivity of the organic solvent gas, the average primary particle diameter of tin oxide is set to 35 n.
It is preferably m or more. The average primary particle size is 70
When the average particle size is not less than nm, the primary particles of tin oxide are too large and the bond between the particles is weakened. Therefore, from the viewpoint of strength of the sintered body, the average primary particle size is preferably 70 nm or less. Further, if the average primary particle size is set to 40 nm or more, the sensitivity to various gases shown in the drawing can be further increased. Again 5
The sensitivity is best near 0 nm (45 nm to 55 nm). (5) Sensitivity characteristics for various gases FIG. 7 shows the sensitivity characteristics for various gases of the sensor of the present application using tin oxide having an average primary particle diameter of 53 nm (only the average primary particle diameter and the film thickness are adjusted). There is. Such odorous gases (ethanol, acetone, ethyl acetate, acetaldehyde, trimethylamine, styrene,
Propionic acid) is very sensitive and odorless gases (isobutane, hydrogen, carbon monoxide, methane) are extremely low. Therefore, a good odor sensor is obtained. However, the film thickness is set to 10 to 50 μm, and the sensor temperature at the time of gas detection is set to 450 to 550 ° C.

(6) Effects of addition of lanthanum or lead Sensitivity characteristics of the sensor shown in FIG. 7 to which lanthanum (La) is added to various gases are shown in FIG. 8 and sensitivity characteristics of lead to which Pb is added are shown to various gases. It is shown in FIG.
Comparing each figure, the sensitivity to hydrogen, carbon monoxide, isobutane, and methane, which have no odor, is greatly reduced by the addition of these elements, and the selectivity (discrimination) of odor gas to these gases is greatly reduced. You can see that it has been obtained.

(7) Effect of forming coating layer The results of the sensor shown in FIG. 9 in which a coating layer is provided on the surface of the gas-sensitive layer are shown in FIGS. 10, 11, 12, and 13. In these figures, the coating layers are zinc oxide (ZnO), titanium oxide (TiO ₂ ), tungsten oxide (WO ₃ ), molybdenum oxide (MoO ₃ ), respectively.
Is. (A) Zinc oxide (ZnO) coating layer This sensor, like the one described above, is also highly sensitive to hydrogen sulfide, propionic acid, acetaldehyde, ethanol, acetone, ethyl acetate, etc. Suitable for odor sensor. (B) Titanium oxide (TiO ₂ ) coating layer This sensor uses hydrogen sulfide, propionic acid, ethanol,
Since it has high sensitivity to acetaldehyde, acetone, ethyl acetate, etc., it is suitable as an odor sensor for these organic solvent gas odors. (C) Tungsten oxide (WO ₃ ) coating layer This sensor is composed of hydrogen sulfide, propionic acid, styrene, trimethylamine, methyl sulfide (not shown) (these gases have a considerable malodor), ethanol, acetaldehyde, Since it has high sensitivity to acetone and ethyl acetate, it is suitable as a sensor for these malodorous gas odors. (D) Molybdenum oxide (MoO ₃ ) coating layer This sensor is particularly sensitive to hydrogen sulfide, propionic acid, trimethylamine, ethanol, acetaldehyde, styrene, and methyl mercaptan (not shown). Suitable for sensors.

[Other Embodiments] Other embodiments of the present application will be described below. As the substrate, other than the above alumina substrate,
Any substrate may be used as long as it is made of a material having electrical insulation and heat resistance and good thermal conductivity. Although the gas sensitive body and the heater are provided on different surfaces of the alumina substrate, they may be provided on the same surface. In the above embodiment, the resistance change due to the odor adsorption of the gas-sensitive material is independently detected (or the structure), but this resistance change is detected as a change in the combined resistance of the resistance of the heater and the resistance of the gas-sensitive material. It may have a configuration (or a structure). In short, as long as the resistance change due to the odor adsorption of the metal oxide semiconductor can be detected, it is not limited to the sensor type. In the above examples, a platinum thin film heater was provided on the back surface of the alumina substrate in order to heat the gas sensitive part to a predetermined temperature range, but this heater is provided separately from the substrate and the metal oxide semiconductor film layer. The heater may be provided by surrounding these portions from the peripheral portion.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a substrate type semiconductor gas sensor.

FIG. 2 is a diagram showing the firing temperature dependence of the average primary particle diameter and specific surface area of tin oxide.

FIG. 3 is a diagram showing the relationship between the average primary particle size and sensitivity to ethanol and hydrogen gas.

FIG. 4 is a diagram showing the relationship between sensitivity to ethanol and hydrogen gas and film thickness.

FIG. 5 is a diagram showing a relationship between sensitivity and sensor temperature in sensors having different average primary particle diameters.

FIG. 6 is a graph showing the average primary particle size dependence for various gases.

FIG. 7 is a diagram showing the sensitivity characteristics of the sensor of the present invention without addition processing and coating processing.

FIG. 8 is a diagram showing sensitivity characteristics of the sensor of the present invention to which lanthanum is added, for various gases.

FIG. 9 is a diagram showing the sensitivity characteristics of the present sensor containing lead to various gases.

FIG. 10 is a diagram showing sensitivity characteristics of a sensor coated with zinc oxide to various gases.

FIG. 11 is a diagram showing sensitivity characteristics of a sensor coated with titanium oxide to various gases.

FIG. 12 is a diagram showing sensitivity characteristics of a sensor coated with tungsten oxide to various gases.

FIG. 13 is a diagram showing sensitivity characteristics of a sensor coated with molybdenum oxide to various gases.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate type semiconductor gas sensor 2 Substrate 3 Metal oxide semiconductor film layer 4 Detection electrode 6 Heating means 7 Heating means 8 Coating layer

Claims (9)

[Claims] 1. A detection electrode (3) comprising a metal oxide semiconductor film layer (3) containing tin oxide as a main component on a substrate (2) and electrically connected to the metal oxide semiconductor film layer (3). 4) The substrate-type semiconductor gas sensor according to claim 4, wherein the average primary particle diameter of tin oxide is 35 nm to 70 nm, and the thickness of the metal oxide semiconductor film layer (3) is 10 μm.
To 50 μm, and a substrate-type semiconductor gas sensor in which at least one of lead (Pb) and lanthanum (La) is added to the metal oxide semiconductor film layer (3). 2. The substrate-type semiconductor gas sensor according to claim 1, comprising the metal oxide semiconductor film layer (3) at 450 ° C.
To a gas detector equipped with heating means (6) and (7) for maintaining the temperature at 550 ° C. 3. A detection electrode (3) comprising a metal oxide semiconductor film layer (3) containing tin oxide as a main component on a substrate (2) and electrically connected to the metal oxide semiconductor film layer (3). A substrate-type semiconductor gas sensor configured with 4),
The average primary particle diameter of the tin oxide is 35 nm to 70 nm
And the thickness of the metal oxide semiconductor film layer (3) is 10 μm to 50 μm, and the metal oxide semiconductor film layer (3) has at least one of lead (Pb) and lanthanum (La). And tungsten oxide (WO ₃ ) is added to the surface of the metal oxide semiconductor film layer ( ₃ ).
Alternatively, a substrate type semiconductor gas sensor having a coating layer (8) of molybdenum oxide (MoO ₃ ). 4. The substrate-type semiconductor gas sensor according to claim 3, wherein the coating layer (8) of tungsten oxide (WO ₃ ) or molybdenum oxide (MoO ₃ ) has a thickness of 10 to 100 μm. 5. The substrate-type semiconductor gas sensor according to claim 3, comprising the metal oxide semiconductor film layer (3) at 450 ° C.
To a gas detector equipped with heating means (6) and (7) for maintaining the temperature at 550 ° C. 6. A detection electrode (3) comprising a metal oxide semiconductor film layer (3) containing tin oxide as a main component on a substrate (2) and electrically connected to the metal oxide semiconductor film layer (3). A substrate-type semiconductor gas sensor configured with 4),
The average primary particle diameter of the tin oxide is 35 nm to 70 nm
And the thickness of the metal oxide semiconductor film layer (3) is 10 μm to 50 μm, and the metal oxide semiconductor film layer (3) has at least one of lead (Pb) and lanthanum (La). And a coating layer (8) of zinc oxide (ZnO) or titanium oxide (TiO ₂ ) on the surface of the metal oxide semiconductor film layer (3). 7. The zinc oxide (ZnO) or titanium oxide (TiO ₂ ) coating layer (8) has a thickness of 10
The substrate-type semiconductor gas sensor according to claim 6, which has a thickness of -100 μm. 8. The substrate-type semiconductor gas sensor according to claim 6, wherein the metal oxide semiconductor film layer (3) is at 450 ° C.
To a gas detector equipped with heating means (6) and (7) for maintaining the temperature at 550 ° C. 9. The lead (Pb) or lanthanum (La).
The substrate-type semiconductor gas sensor according to any one of claims 1, 3, 4, 6, and 7, wherein the addition amount of any one or more of the above is 0.5 to 8 atm%.