Structure of gas sensor
阅读说明:本技术 气体传感器的结构 (Structure of gas sensor ) 是由 薛丁仁 萧育仁 林育德 李彦希 陈永祥 谢嘉民 于 2018-09-11 设计创作,主要内容包括:本发明为气体传感器的结构,包含:气体侦测器芯片,该芯片的感测材料背部为一中空结构,感测材料下有一绝缘层,感测材料周围有一微型加热器,感测材料附着于感测电极上,感测材料为二金属氧化物半导体或一金属氧化物半导体和一反应层的粗糙表面的感测层的复合结构,其中该二金属氧化物之间具有一界面层,其能够增加本发明气体感测效率;经由本发明所提供的气体侦测器结构,可于硅基板上完成悬浮气体感测结构,并能将芯片尺寸做到最小化。(The present invention is a structure of a gas sensor, including: the gas detector chip, the sensing material back of the chip is a hollow structure, there is an insulating layer under the sensing material, there is a miniature heater around the sensing material, the sensing material is attached to sensing electrode, the sensing material is the composite structure of two metal oxide semiconductors or a metal oxide semiconductor and sensing layer of the rough surface of a reaction layer, wherein there is an interface layer between two metal oxides, it can increase the gas sensing efficiency of the invention; the gas detector structure provided by the invention can complete a suspended gas sensing structure on a silicon substrate and can minimize the chip size.)
1. A micro gas sensor is characterized in that the micro gas sensor comprises a substrate, a dielectric layer and a sensing layer, wherein the dielectric layer is arranged on the substrate and comprises a heating element, two electrodes and the sensing layer is arranged on the heating element and connected with the two electrodes, and the micro gas sensor is characterized in that:
the sensing layer is composed of a first metal oxide layer and a reaction layer, wherein the reaction layer is arranged on the first metal oxide layer, and the surface of the reaction layer is a rough surface.
2. The micro gas sensor as recited in claim 1, wherein the heating element and the two electrodes are further disposed on the dielectric layer.
3. The micro gas sensor as recited in claim 1, wherein the substrate is discontinuous such that the dielectric layer is elevated above the substrate, creating a heat dissipation area that is not in direct contact with the substrate.
4. The micro gas sensor as recited in claim 1, wherein the reaction layer is made of a material selected from the group consisting of lanthanum carbonate and nano-gold.
5. The micro gas sensor as recited in claim 1, wherein the first metal oxide layer is made of a material selected from the group consisting of tungsten oxide, zinc oxide, and tin oxide, the tungsten oxide material is tungsten trioxide, and the tin oxide material is tin dioxide.
6. The micro gas sensor as recited in claim 1, wherein the heating element is made of a material selected from the group consisting of titanium, gold, platinum, silver and tantalum.
7. The micro gas sensor of claim 1, wherein the dielectric layer is made of a material selected from the group consisting of silicon nitride, silicon oxide, silicon oxynitride, and any combination thereof.
8. A micro gas sensor is characterized in that the micro gas sensor comprises a substrate, a dielectric layer and a sensing layer, wherein the dielectric layer is arranged on the substrate and comprises a heating element, two electrodes and the sensing layer is arranged on the heating element and connected with the two electrodes, and the micro gas sensor is characterized in that: the sensing layer is composed of a first metal oxide layer and a second metal oxide layer, wherein the first metal oxide layer is arranged on the second metal oxide layer, the first metal oxide layer and the second metal oxide layer are respectively made of one of combinations of zinc oxide, tungsten oxide and tin oxide, the tungsten oxide material can be tungsten trioxide, and the tin oxide material can be tin dioxide.
9. The micro gas sensor as recited in claim 8, wherein the surface of the first metal oxide layer is a rough surface.
10. The micro gas sensor as recited in claim 8, wherein a reaction layer is further disposed on the sensing layer.
11. The micro gas sensor as recited in claim 8, wherein the heating element and the two electrodes are further disposed on the dielectric layer.
12. The micro gas sensor as recited in claim 8, wherein the substrate is discontinuous such that the dielectric layer is elevated above the substrate, creating a heat dissipation area that is not in direct contact with the substrate.
13. The micro gas sensor as recited in claim 8, wherein the heating element is made of a material selected from the group consisting of titanium, gold, platinum, silver and tantalum.
14. The micro gas sensor of claim 8, wherein the dielectric layer is made of a material selected from the group consisting of silicon nitride, silicon oxide, silicon oxynitride, and any combination thereof.
15. The micro gas sensor of claim 8, wherein the surface of the first oxide metal layer further comprises a nano metal layer disposed on the surface of the first metal oxide layer.
16. The micro gas sensor of claim 8, wherein an interface layer is between the first oxide metal layer and the second metal oxide layer.
17. The micro gas sensor of claim 16, wherein the interface layer is formed by thermal diffusion and phase change reactions of tungsten oxide and tin oxide of the first metal oxide layer and the second metal oxide layer.
18. A micro gas sensor is characterized in that the micro gas sensor comprises a substrate, at least one dielectric layer and a sensing layer, wherein the dielectric layer is arranged on the substrate and comprises a heating element, two electrodes and the sensing layer is arranged on the heating element and connected with the two electrodes, and the micro gas sensor is characterized in that: the sensing layer is composed of at least one first metal oxide layer, and the stress of the dielectric layer is between 1MPa and 20 MPa.
19. The micro gas sensor as recited in claim 18, wherein the sensing layer is made of tin oxide or tungsten oxide, the tungsten oxide is tungsten trioxide, and the tin oxide is tin dioxide.
20. The micro gas sensor of claim 18, wherein the dielectric layer is made of a material selected from the group consisting of silicon nitride, silicon oxide, silicon oxynitride, and any combination thereof.
21. The micro gas sensor as recited in claim 18, wherein the surface of the first metal oxide layer is a rough surface.
22. The micro gas sensor of claim 18, wherein the surface of the first oxide metal layer further comprises a nanometal layer disposed on the surface of the first metal oxide layer.
23. The micro gas sensor as recited in claim 22, wherein the nano metal layer is one of a group consisting of ti, au, pt, ag, pd and ta.
24. The miniature gas sensor of claim 18, wherein the dielectric layer has a thickness of between 2000 a and 25000 a.
Technical Field
The present invention relates to a gas sensor and a method for manufacturing the same, and more particularly, to a micro gas sensor and a method for manufacturing the same.
Background
With the development of social commercialization and industrialization, more and more indoor spaces are built and more vehicles are used, which provide people with rest, work and commute needs, however, when people are in these closed indoor spaces, the air will not circulate and the concentration of harmful gas will accumulate, which will affect the quality of life of people in the spaces, and will directly harm human bodies, generally speaking, the indoor carbon dioxide concentration is below 1,000ppm and is generally regarded as a normal and well ventilated concentration value, when the indoor carbon dioxide concentration is increased to 1,000 ppm-2,000 ppm, oxygen will be insufficient, people will feel sleepy, and people will feel irritated, when the indoor carbon dioxide concentration is further increased to 2,000 ppm-5,000 ppm, discomfort will begin to human bodies, including headache and somnolence, and with carelessness, Attention deficit, accelerated heartbeat, and mild nausea, and exposure to indoor carbon dioxide concentrations greater than 5,000ppm can result in severe hypoxia, resulting in permanent brain damage, coma, and even death. In the practical measurement of daily life, the measured value of the carbon dioxide concentration in the space of daily activities of people can reach about 2,000ppm to 3,000ppm due to insufficient ventilation effect of the indoor air conditioner or excessive people in the space, which may cause people to fall asleep and cause slight discomfort, and if the indoor carbon dioxide concentration is not further controlled, the indoor carbon dioxide concentration may continue to rise, so that people in the space are exposed to danger,
on the other hand, carbon monoxide is a colorless and odorless chemical substance generated by incomplete combustion of a carbon-containing substance, so that the carbon monoxide still contacts with carbon monoxide in a living environment in the situations of incomplete combustion of natural gas and gas or incomplete combustion of locomotive exhaust in our lives, and the situations are in close relation. The affinity of carbon monoxide with hemoglobin of a human body is two to three hundred times higher than that of oxygen with hemoglobin, so when the carbon monoxide is inhaled by the human body, the carbon monoxide and the oxygen in the human body compete to combine with the hemoglobin to replace the combination of the oxygen and the hemoglobin, the oxygen content of blood of the human body is reduced, people gradually lose consciousness and coma under the condition that the people cannot perceive abnormal conditions, and then die due to heart and brain damage, and in view of the harm of carbon monoxide poisoning to life, the closed space is a key for early discovery of carbon monoxide concentration rise.
Currently, the gas sensor used in a general workshop is mainly an infrared type gas sensor, which uses infrared rays to provide energy to excite a gas to generate changes of temperature, displacement or frequency, and determines the type and concentration of the gas by the degree of absorption of the infrared rays by the gas and detecting the absorption condition of the characteristic absorption peak position. By sensing gas with infrared rays, although the accuracy of the measurement result is high, the measurement result is quite easily affected by ambient temperature, and the gas sensor has large volume, high price and difficult miniaturization, thereby causing difficulty to a certain extent in use and popularization.
In addition, another gas sensor is a gas sensor in the form of a semiconductor, in which a metal oxide material is sintered into a semiconductor, and the metal oxide material of the semiconductor is brought into contact with a combustible gas while a heater is kept at a high temperature, so that a certain relationship is expected between a change in resistance and a gas concentration to achieve an effect of detecting carbon monoxide gas.
Based on the above, it can be understood that the detection of gas concentration has a great relationship to the safety of indoor space, but the gas sensors in the current factories have their limitations in use, so how to provide a miniature and accurate gas sensor is a critical technical threshold in the field.
Disclosure of Invention
The main object of the present invention is to provide a micro gas sensor which has a small volume and a sensitive detection response, can be widely used in various enclosed spaces, portable devices or vehicles, and has high utility.
Another objective of the present invention is to provide a micro gas sensor, which uses a sensing material with high sensitivity, and can effectively reduce the temperature required by the sensing layer during sensing, thereby avoiding adverse effects of heat energy on the sensing process.
It is another object of the present invention to provide a method for manufacturing a micro gas sensor, which can coat a sensing material on a substrate, and make the sensing material have good adhesion and thickness control.
In order to achieve the above object, the present invention discloses a micro gas sensor, which comprises a substrate, a dielectric layer disposed on the substrate, wherein the dielectric layer comprises a heating element and two electrodes, and a sensing layer disposed on the heating element and connected to the two electrodes, wherein the sensing material layer comprises a metal oxide layer and a reaction layer, the reaction layer is disposed on the metal oxide layer, and the surface of the reaction layer is a rough surface.
In one embodiment of the present invention, it is also disclosed that the heating device and the two electrodes may be further disposed on the dielectric layer.
In an embodiment of the present invention, it is also disclosed that the substrate is a discontinuous structure, such that the dielectric layer is raised above the substrate, resulting in a heat dissipation area not directly contacting the substrate.
In an embodiment of the present invention, the material of the reaction layer is selected from a group consisting of lanthanum carbonate and nanogold.
In an embodiment of the present invention, a material of the metal oxide layer is selected from a group consisting of tungsten oxide, zinc oxide, and tin oxide.
In one embodiment of the present invention, the material of the heating element is selected from a group consisting of titanium, platinum, silver and tantalum.
In an embodiment of the invention, the dielectric layer is made of a material selected from the group consisting of silicon nitride, silicon oxide, or silicon oxynitride, and any combination thereof.
In order to achieve the above object, the present invention further discloses a micro gas sensor, which is a semiconductor gas sensor, and includes a substrate, a dielectric layer, a heating element, two electrodes, and a sensing layer, wherein the sensing layer is disposed on the heating element and connected to the two electrodes, and the sensing layer has a first metal oxide layer and a second metal oxide layer, the second metal oxide layer is disposed on the first metal oxide layer, and the first metal oxide layer and the second metal oxide layer are made of tin oxide and tungsten oxide, respectively.
In an embodiment of the invention, the surface of the second metal oxide layer is a rough surface.
In one embodiment of the present invention, it is also disclosed that the heating element and the two electrodes may be further disposed on the dielectric layer, wherein the material of the heating element is one selected from the group consisting of titanium, gold, platinum, silver and tantalum.
In an embodiment of the present invention, it is also disclosed that the substrate is a discontinuous structure, such that the dielectric layer is raised above the substrate, resulting in a heat dissipation area not directly contacting the substrate.
In an embodiment of the present invention, a reaction layer is further disposed on the sensing layer.
In one embodiment of the present invention, it is also disclosed that the heating element and the two electrodes may be further disposed on the dielectric layer.
In an embodiment of the invention, the dielectric layer is made of a material selected from the group consisting of silicon nitride, silicon oxide, or silicon oxynitride, and any combination thereof.
In an embodiment of the present invention, it is also disclosed that the surface of the first oxide metal layer further includes a nano metal layer disposed on the surface of the first metal oxide layer.
In an embodiment of the present invention, an interfacial layer is disposed between the first oxide metal layer and the second oxide metal layer.
In an embodiment of the invention, the interfacial layer is formed by a thermal diffusion and phase change reaction of the tungsten oxide and the zinc oxide of the first metal oxide layer and the second metal oxide layer to form a mixed material of the tungsten oxide and the zinc oxide.
In order to achieve the above object, the present invention further discloses a micro gas sensor, which is a semiconductor gas sensor, and comprises a substrate, at least one dielectric layer disposed on the substrate and comprising a heating element and two electrodes, and a sensing layer disposed on the heating element and connected to the two electrodes, wherein the sensing layer is at least composed of a first metal oxide layer, and the stress of the dielectric layer is between 1MPa and 20 MPa.
In an embodiment of the invention, the material of the sensing layer is zinc oxide or tungsten oxide.
In an embodiment of the invention, the material of the dielectric layer is selected from one of a combination of silicon nitride, silicon oxide, or silicon oxynitride, and any combination thereof.
In an embodiment of the present invention, it is also disclosed that the surface of the first metal oxide layer is a rough surface.
In an embodiment of the present invention, it is also disclosed that the surface of the first oxide metal layer further includes a nano metal layer disposed on the surface of the first metal oxide layer.
In an embodiment of the present invention, the material of the nano-metal layer is one of a combination of titanium, gold, platinum, silver, palladium and tantalum.
In one embodiment of the present invention, the dielectric layer is also disclosed as having a thickness of 2000 to 25000 angstroms.
Drawings
FIG. 1: it is a side exploded view of a preferred embodiment of the present invention;
FIG. 2: which is a cross-sectional view of another preferred embodiment of the present invention;
fig. 3A to 3C: the gas detection efficacy of a preferred embodiment of the present invention is illustrated.
FIG. 4: which is an exploded side view of a second embodiment of the present invention;
FIG. 5: which is a cross-sectional view of a second embodiment of the invention;
FIG. 6: it is a schematic diagram of the gas detection efficacy of the second embodiment of the present invention; and
FIG. 7: which is a cross-sectional view of a third embodiment of the present invention.
[ brief description of the drawings ]
10 base plate
20 dielectric layer
30 heating element
40 electrodes
50 sensing layer
510 first metal oxide layer
515 rough surface
520 reaction layer
530 second metal oxide layer
535 interfacial layer
60 nm metal layer
Detailed Description
In order to provide a further understanding and appreciation for the structural features and advantages achieved by the present invention, the following detailed description of the presently preferred embodiments is provided:
the invention provides a novel micro gas sensor structure aiming at the conditions of large volume, high price, difficult miniaturization and insufficient accuracy of the existing gas sensor. In addition, by arranging the reaction layer, the material of the reaction layer is lanthanum carbonate or nano gold which is used as a sensing material of the semiconductor type gas sensor or arranging the two metal oxide layers, the material of the reaction layer is zinc oxide or tungsten oxide which is used as a sensing material of the semiconductor type gas sensor, so that different gases are sensed, the sensing sensitivity of the gas sensor can be effectively improved, and the accuracy of the gas sensor is improved.
Therefore, the present invention provides a novel micro gas sensor structure, which is based on a semiconductor type gas sensor structure, the semiconductor structure comprises a heating sensing element, when a sensing material layer is arranged on the heating element, the reaction layer of the sensing layer has lanthanum carbonate or nano-gold which can generate free electrons after contacting with gas and reacting, because the reaction of the lanthanum carbonate or nano-gold contacting with the gas is very sensitive, the potential change generated by the lanthanum carbonate or nano-gold is easy to be measured by the heating sensing element, and the gas concentration is estimated according to the change of the resistance value, so as to achieve the purpose of high-sensitivity detection.
The following further describes the components and properties of the micro gas sensor of the present invention:
please refer to fig. 1, which is a side exploded view of a micro gas sensor according to a first embodiment of the present invention. As shown in the drawings, the present invention provides a
Based on the above sensor structure, the gas sensor provided by the present invention can sense different gases by providing different reaction layer materials, which will be described below.
When the material of the
CO2+O2-→CO3 2-(formula one)
La2O2CO3+CO3 2-→La2O2CO3+1/2O2+CO2+2e-(formula II)
In addition, when the material of the
CO+O2-→CO2+2e-(formula IV)
In the micro gas sensor, the
In the micro gas sensor as described above, wherein the
As mentioned in the above paragraphs, the
As mentioned above, in the micro gas sensor, the
Referring to fig. 2 of the drawings, which is another preferred embodiment of the present invention, as shown in the drawings, the
The following examples are provided to illustrate the technical and scientific content, features and advantages of the present invention, and are not to be construed as limiting the scope of the present invention.
EXAMPLE 1 testing of structural Properties of lanthanum-containing Compound micro gas sensor
Referring to fig. 3A, which is a schematic diagram illustrating the sensing time and the resistance change of the lanthanum compound-containing micro gas sensor when sensing carbon dioxide gas, as shown in the figure, the concentration of carbon dioxide in the sensing environment is 600ppm in the first 120 seconds, the concentration of carbon dioxide in the sensing environment is increased seven times in the next ten minutes in a manner of increasing carbon dioxide by 400ppm each time, and the change of the resistance value of the lanthanum compound-containing micro gas sensor is observed; as can be seen from the graph, each time the carbon dioxide concentration in the sensing environment is increased, the resistance value of the gas sensor rapidly decreases to a stable value and is maintained at the stable value until the carbon dioxide concentration in the sensing environment is increased next time, and the difference between the initial resistance value and the final resistance value can reach sixty-thousand ohms, which shows that the gas sensor has stable gas sensing capability and wide sensing range; finally, when the carbon dioxide gas is stopped to make the carbon dioxide concentration in the sensing environment return to the initial state, the resistance value of the gas sensor can return to the initial value within a short time, and the difference between the resistance value of the gas sensor and the resistance value before the sensing is started is not large, which is sufficient for the high measurement stability of the gas sensor.
Referring to fig. 3B, it is a graph comparing the measurement results of the lanthanum-containing compound micro gas sensor provided in the present application with the carbon dioxide sensor in the prior art, where the data of the square dots is the content measured by the currently available carbon dioxide sensor, and the data of the circular dots is the content measured by the lanthanum-containing compound micro gas sensor provided in the present invention, as shown in the figure, the lanthanum-containing compound micro gas sensor provided in the present application can not only sense carbon dioxide in a larger concentration range, but also more accurately reflect the actual carbon dioxide concentration in the environment.
Example 2 structural Properties of Nanogold micro gas sensor
Referring to fig. 3C, which is a graph showing the trend of the change in power and sensitivity of the nano-gold micro gas sensor in a carbon monoxide environment under different annealing time conditions, when the gold-containing metal layer is not processed by the annealing step (i.e., seconds are zero), the gold-containing metal layer does not form nano-gold dots, so that the gas sensing capability of the micro gas sensor is not improved when the micro gas sensor is operated (i.e., the heating power of the sensor is increased); in addition, although the gas sensors prepared by different annealing times have similar resistivity change trends under different conditions, the micro gas sensor prepared by the annealing step for 30 seconds not only has the maximum sensitivity (35%), but also has a more stable change trend than the groups of the annealing step for 15 seconds and 60 seconds, obviously has the most complete and proper distribution of nano-gold points, can adsorb more carbon monoxide, and obtains the highest and most accurate value in the measurement range.
Next, please refer to fig. 4, which is a side exploded view of a micro gas sensor according to a second embodiment of the present invention. As shown in the drawings, the present invention provides a
Wherein the content of the first and second substances,the first
As described above, the
In the micro gas sensor as described above, wherein the
In view of the above, the
In view of the above-mentioned micro gas sensor structure, the
Referring to fig. 5 of the drawings, which is a second embodiment of the present invention, as shown in the drawings, the
The following examples are provided to illustrate the technical and scientific content, features and advantages of the present invention, and are not to be construed as limiting the scope of the present invention.
EXAMPLE 3 gas sensor structural Property test of bimetal oxide layer
Referring to fig. 6, which is a schematic diagram illustrating the sensing time and current change of the micro gas sensor including the first
Please refer to fig. 7, which is a cross-sectional view of a micro gas sensor according to a third embodiment of the present invention. As shown in the figure, the present invention provides a
Wherein, the material of the
In view of the above, the
In summary, the present invention provides a highly stable micro gas sensor and a method for fabricating the same, wherein a semiconductor structure is provided with sensing layers of different materialsThe invention discloses lanthanum carbonate to detect carbon dioxide, nano gold to detect carbon monoxide, and uses semiconductor process technology through the gas sensor structure of the invention, thereby reducing the volume of the gas sensor, solving the problems of large volume, high price and difficult miniaturization of the current gas sensor, especially the carbon dioxide gas sensor, effectively reducing the volume required by the gas sensor, increasing the applicability thereof, and providing a novel micro gas sensor structure. Furthermore, tungsten oxide (WO) is utilized3) Tin oxide and zinc oxide are used as sensing materials of semiconductor type gas sensors to sense ammonia gas, and as shown in the embodiments, the sensing sensitivity and accuracy of the gas sensor are effectively improved. Therefore, the invention provided by the present application indeed has superior and advanced efficacy compared with the prior art, and meets the requirements of patent application.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not intended to limit the scope of the present invention, which is defined by the appended claims.
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