CN112611788A - Semiconductor hydrogen sulfide gas sensor - Google Patents
Semiconductor hydrogen sulfide gas sensor Download PDFInfo
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- CN112611788A CN112611788A CN202011578253.9A CN202011578253A CN112611788A CN 112611788 A CN112611788 A CN 112611788A CN 202011578253 A CN202011578253 A CN 202011578253A CN 112611788 A CN112611788 A CN 112611788A
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- sulfide gas
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
- G01N27/128—Microapparatus
Abstract
The invention discloses a semiconductor hydrogen sulfide gas sensor which comprises a substrate, and an induction electrode and a reference electrode which are positioned on the substrate, wherein the induction electrode and the reference electrode respectively comprise two parts, two ends of the induction electrode and the reference electrode are respectively connected with a bonding pad, and the two induction electrodes and the two reference electrodes form a Wheatstone bridge through external leads of the bonding pads; the sensing electrode and the bonding pad are exposed to air, the reference electrode is covered by an insulating layer, and the sensing electrode is made of metal silver. The sensor disclosed by the invention has the advantages of small size, low power consumption, low cost, sensitive detection and good stability.
Description
Technical Field
The invention relates to a gas sensor, in particular to a semiconductor hydrogen sulfide gas sensor.
Background
Hydrogen sulfide is a colorless, flammable and highly toxic gas, and is widely produced and exists in industrial processes such as coal mining, petroleum refining and the like. Meanwhile, hydrogen sulfide, as an atmospheric pollutant, seriously affects the quality of life of human beings, and has been classified as a toxic and highly dangerous chemical by occupational safety and health standards. The gas sensor is a device which can convert the gas concentration into corresponding output signals, and has important application in the aspects of industrial production control, safety alarm, food industry, clinical diagnosis, environmental protection, homeland safety and the like.
At present, there are three detection methods for hydrogen sulfide gas sensors: semiconductor metal oxide method, ultraviolet absorption method, electrochemical method.
A hydrogen sulfide gas sensor based on semiconductor metal oxide is composed of a heating plate and a metal oxide structure, when the concentration of hydrogen sulfide gas is increased, the conductivity of metal oxide is increased, so that the concentration information of hydrogen sulfide gas is obtained. The sensor has the advantages of small size, low power consumption, low cost and the like, but has the defects of large temperature drift, obvious gas cross response, low sensitivity and the like.
The hydrogen sulfide gas sensor based on the ultraviolet absorption method obtains concentration information of hydrogen sulfide gas by detecting the absorption of the hydrogen sulfide gas to ultraviolet energy, is a physical detection method, and is commonly used in the fields of gas analysis in laboratories and the like. The sensor has the advantages of high detection precision, good stability, small gas cross response and the like, but is high in price, large in size and not suitable for large-scale field application.
The hydrogen sulfide gas sensor based on the electrochemical principle utilizes the electrochemical oxidation process of gas to be measured on working electrodes in an electrolytic cell, collects current generated by electrochemical reaction through three groups of electrodes, the current is in direct proportion to the concentration of the gas and follows Faraday's law, and therefore the concentration of the gas to be measured can be determined by measuring the current. The sensor has the advantages of high precision, low power consumption, small gas cross response and the like, but has the defects of regular calibration, general service life of 1-3 years, high packaging cost and the like.
Disclosure of Invention
In order to solve the technical problems, the invention provides a semiconductor hydrogen sulfide gas sensor, which aims to achieve the purposes of small size, low power consumption, low cost, sensitive detection and good stability.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a semiconductor hydrogen sulfide gas sensor comprises a substrate, and an induction electrode and a reference electrode which are positioned on the substrate, wherein the induction electrode and the reference electrode respectively comprise two parts, two ends of the induction electrode and two ends of the reference electrode are respectively connected with a bonding pad, and the two induction electrodes and the two reference electrodes are externally connected with a lead through the bonding pads to form a Wheatstone bridge; the sensing electrode and the bonding pad are exposed to air, the reference electrode is covered by an insulating layer, and the sensing electrode is made of metal silver.
In the above scheme, the substrate is further provided with a heating electrode, and two ends of the heating electrode are respectively connected with the bonding pads.
In a further technical scheme, the heating electrode is positioned right below or right above the induction electrode and the reference electrode, and the upper layer and the lower layer are separated by an insulating layer.
In a further technical scheme, the heating electrode is positioned on the same layer as the sensing electrode and the reference electrode, and the heating electrode is positioned between the reference electrode and the sensing electrode or positioned on one side of the reference electrode and the sensing electrode.
In the above embodiment, the reference electrode serves as a heating electrode.
In a further technical scheme, the induction electrode, the reference electrode, the heating electrode and the bonding pad are all manufactured by sputtering a metal silver material in an electronic evaporation mode.
In a further technical scheme, a chemical plating mode is adopted to continuously grow the silver nano porous structure on the silver-based film of the induction electrode.
In the above scheme, the insulating layer is of a multilayer structure, different insulating layers are of the same material or different materials, and the insulating layer is formed by depositing SiO in an LPCVD or PECVD manner2Or SiN.
In a further technical scheme, the induction electrode and the insulating layer above the bonding pad are removed through an etching process.
In the above scheme, the substrate is a silicon substrate.
Through the technical scheme, the semiconductor hydrogen sulfide gas sensor provided by the invention has the following beneficial effects:
1. the invention utilizes the principle that the reaction of silver and hydrogen sulfide gas affects the resistivity of silver to convert the concentration of the hydrogen sulfide gas into an electric signal for output. The device can be processed by using a low-cost and high-consistency semiconductor technology, and the induction electrode and the reference electrode are combined to form a Wheatstone bridge, so that the problems of temperature drift, zero drift and the like are effectively solved.
2. The heating electrode is arranged, so that the temperature difference between the induction electrode and the reference electrode is reduced, the gas measurement error caused by temperature is reduced, and the stability of an electric signal is ensured; the working temperature of the sensor is increased to promote the silver sulfurization reaction, so that the sensitivity of the sensor is improved, and the problems of large temperature drift, low sensitivity and the like of a semiconductor gas sensor are effectively solved by the design.
3. The invention adopts an electronic evaporation mode to sputter metallic silver materials to manufacture the induction electrode, the reference electrode, the heating electrode and the bonding pad, and simultaneously proposes a chemical plating mode to continuously grow the silver nano porous structure on the silver-based film of the induction electrode so as to increase the specific surface area of the induction electrode and improve the gas detection sensitivity.
4. The invention adopts the MEMS structure and uses the metallic silver as the reaction material, thereby avoiding the problems of liquid leakage, volatilization and the like of the electrochemical sensor which uses the electrolyte as the reaction medium, and simultaneously, the invention adopts the high-precision MEMS packaging process, thereby avoiding the problems of complex packaging process of the traditional electrochemical sensor, large influence of the size and the position of the packaged structural member on the overall performance of the gas sensor, easy sensitivity deviation, liquid leakage, service life reduction and the like.
5. The gas concentration is calculated by designing the Wheatstone bridge and reading the electric signals output by two ends of the bridge, and the method has high sensitivity.
6. The invention utilizes the existing mature silicon process flow, has relatively simple design and low price, and therefore, the sensor also has the advantages of low cost and easy mass production.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.
FIG. 1 is a schematic view of a semiconductor hydrogen sulfide gas sensor disclosed in embodiment 1 of the present invention;
FIG. 2 is a schematic view of a semiconductor hydrogen sulfide gas sensor disclosed in embodiment 2 of the present invention;
FIG. 3 is a schematic view of a semiconductor hydrogen sulfide gas sensor disclosed in embodiment 3 of the present invention;
FIG. 4 is a schematic view of a semiconductor hydrogen sulfide gas sensor disclosed in embodiment 4 of the present invention;
FIG. 5 is a schematic view of a semiconductor hydrogen sulfide gas sensor disclosed in embodiment 5 of the present invention;
FIG. 6 is a schematic view of a semiconductor hydrogen sulfide gas sensor disclosed in embodiment 6 of the present invention;
FIG. 7 is a schematic view of a semiconductor hydrogen sulfide gas sensor disclosed in embodiment 7 of the present invention;
FIG. 8 is a plan view showing the positional relationship of the present invention in embodiment 3;
fig. 9 is a schematic diagram of a wheatstone bridge according to an embodiment of the present invention.
In the figure, 1, a silicon substrate; 2. an induction electrode; 3. a reference electrode; 4. heating the electrode; 5. a pad; 6. an insulating layer.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
The invention provides a semiconductor hydrogen sulfide gas sensor which comprises a silicon substrate 1, and an induction electrode 2, a reference electrode 3 and a heating electrode 4 which are positioned on the silicon substrate 1, wherein the induction electrode 2 and the reference electrode 3 respectively comprise two, and two ends of the induction electrode 2, the reference electrode 3 and the heating electrode 4 are respectively connected with a bonding pad 5. The sensing electrode 2 and the pad 5 are exposed to the air, and the reference electrode 3 and the heating electrode 4 are covered with an insulating layer 6.
As shown in embodiment 1 of fig. 1, the heating electrode 4 is located right below the sensing electrode 2 and the reference electrode 3, and the upper and lower layers are separated by an insulating layer 6.
As shown in FIG. 2 of embodiment 2, the heating electrode 4 is located right above the sensing electrode 2 and the reference electrode 3, and the upper and lower layers are separated by the insulating layer 6.
As shown in embodiment 3 of fig. 3, the heating electrode 4 is located at the same layer as the sensing electrode 2 and the reference electrode 3, and the heating electrode 4 is located between the reference electrode 3 and the sensing electrode 2.
As in examples 4 and 5 shown in fig. 4 and 5, the heating electrode 4 is located at the same layer as the sensing electrode 2 and the reference electrode 3, and the heating electrode 4 is located at one side of the reference electrode 3 and the sensing electrode 2.
The reference electrode 3 may be the heating electrode 4, and the reference electrode 3 as the heating electrode 4 may be designed to meet the requirement of a rapid temperature rise when a current is applied. As in embodiments 6 and 7 shown in fig. 6 and 7, the reference electrode 3 may be positioned above or below the sensing electrode 2.
In any way, the temperature difference between the reference electrode 3 and the sensing electrode 2 needs to be ensured to be less than 0.1 ℃.
In the embodiment of the invention, the induction electrode 2, the reference electrode 3, the heating electrode 4 and the bonding pad 5 are all manufactured by sputtering a metal silver material in an electronic evaporation mode. In the manufacturing process, the electrodes are manufactured by adopting a mode of overall silver plating and then partial etching, and the shape of the electrode can be any shape, such as a plane position relation diagram of embodiment 3 shown in fig. 8. After the induction electrode 2 is manufactured, a silver nano porous structure is continuously grown on the silver-based film of the induction electrode 2 in a chemical plating mode, so that the specific surface area of the induction electrode 2 is increased, and the gas detection sensitivity is improved. The window of the sensing electrode 2 can be upward or downward, as long as it is exposed to the gas to be measured.
In the embodiment of the invention, the insulating layer 6 is a multi-layer structure, different insulating layers 6 are made of the same material or different materials, and the insulating layer 6 is deposited with SiO by LPCVD or PECVD2Or SiN. In the manufacturing process of the sensor, the induction electrode 2 and the insulating layer 6 above the bonding pad 5 are removed through an etching process.
Two induction electrodes 2 and two reference electrodes 3 on the silicon substrate 1 are externally connected with wires through bonding pads 5 to form a Wheatstone bridge. The heater electrode 4 acts as a resistor outside the wheatstone bridge configuration. As shown in FIG. 9, the AC/DF terminal is the sensing electrode 2, the BD/CE terminal is the reference electrode 3, and a Wheatstone bridge basic structure is formed. Resistor R in Wheatstone bridge1And R4For the sensing electrode 2 exposed to the gas to be measured, the resistance R2And R3The upper and lower parts are protected by insulating layers 6, are isolated from the gas to be measured and are used as reference electrodes 3.
When the sensor is exposed to hydrogen sulfide gas, the silver of the sensing electrode 2 contacts with the hydrogen sulfide gas to react:
2Ag+H2S→Ag2S+H2
silver loses electron conversion to Ag in the reaction process2And S. The higher the hydrogen sulfide concentration, the more silver is consumed, and Ag is produced2S influences the resistivity of the sensing electrode 2, i.e. the resistance (R) at the AC end and DF end of the Wheatstone bridge1&R4) Since the reference electrode 3 is not in contact with gas, BD/CE terminal resistance (R)2&R3) And is not changed. Vbias is the supply voltage applied to the bridge, and from the bridge structure we know R1、R2Will VbiasPartial pressure, R4The voltage obtained at the two ends of the resistor is V2，R3、R4Will VbiasPartial pressure, R2The voltage obtained at the two ends of the resistor is V1When contacting a gas, R1，R4Resistance value variation causing V2，V1The voltage changes, and the amount of change is calculated as follows:
that is, the change in the resistivity of the induction electrode 2 can be converted into the change in the voltage signal, and the change amount of the electric signal is proportional to the gas concentration, so that the hydrogen sulfide gas concentration is calculated from the change amount of the electric signal. In the experimental stage, after gases to be detected with different concentrations are sequentially measured and added, a relation curve of the concentration and the electric signal is obtained, and then the content of the hydrogen sulfide gas in the gas chamber to be detected can be calculated according to the obtained curve, so that the indirect high-precision real-time monitoring of the concentration of the hydrogen sulfide gas can be realized.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The semiconductor hydrogen sulfide gas sensor is characterized by comprising a substrate, and an induction electrode and a reference electrode which are positioned on the substrate, wherein the induction electrode and the reference electrode respectively comprise two parts, two ends of the induction electrode and two ends of the reference electrode are respectively connected with a bonding pad, and the two induction electrodes and the two reference electrodes are externally connected with a lead through the bonding pads to form a Wheatstone bridge; the sensing electrode and the bonding pad are exposed to air, the reference electrode is covered by an insulating layer, and the sensing electrode is made of metal silver.
2. The semiconductor hydrogen sulfide gas sensor as claimed in claim 1, wherein a heating electrode is further disposed on the substrate, and both ends of the heating electrode are respectively connected to the bonding pads.
3. The semiconductor hydrogen sulfide gas sensor as claimed in claim 2, wherein the heating electrode is located directly below or above the sensing electrode and the reference electrode, and the upper and lower layers are separated by an insulating layer.
4. A semiconductor hydrogen sulfide gas sensor according to claim 2, wherein the heater electrode is located in the same layer as the sensing electrode and the reference electrode, and the heater electrode is located between the reference electrode and the sensing electrode or on one side of the reference electrode and the sensing electrode.
5. A semiconductor hydrogen sulfide gas sensor according to claim 1, wherein the reference electrode serves as a heater electrode.
6. The semiconductor hydrogen sulfide gas sensor according to any one of claims 2 to 5, wherein the sensing electrode, the reference electrode, the heating electrode and the bonding pad are all made by sputtering a metallic silver material by means of electron evaporation.
7. The semiconductor hydrogen sulfide gas sensor as claimed in claim 6, wherein the silver nano-porous structure is grown on the silver-based film of the sensing electrode by electroless plating.
8. The semiconductor hydrogen sulfide gas sensor according to claim 1, wherein the insulating layers are of a multilayer structure, and different insulating layers are of the same material or different materials; the insulating layer is formed by depositing SiO by LPCVD or PECVD2Or SiN.
9. The semiconductor hydrogen sulfide gas sensor as claimed in claim 8, wherein the sensing electrode and the insulating layer over the pad are removed by an etching process.
10. The semiconductor hydrogen sulfide gas sensor of claim 1 wherein the substrate is a silicon substrate.
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| CN202011578253.9A CN112611788A (en) | 2020-12-28 | 2020-12-28 | Semiconductor hydrogen sulfide gas sensor |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113899791A (en) * | 2021-09-16 | 2022-01-07 | 中国电子产品可靠性与环境试验研究所（（工业和信息化部电子第五研究所）（中国赛宝实验室）） | Electrode sensor and preparation method, detection system and detection method thereof |
| CN114113236A (en) * | 2021-11-10 | 2022-03-01 | 北京惠朗时代科技有限公司 | Hydrogen concentration measurement sensor and measurement system |
| CN115436436A (en) * | 2022-11-03 | 2022-12-06 | 南京元感微电子有限公司 | FET gas sensor and processing method thereof |
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Cited By (3)
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| CN113899791A (en) * | 2021-09-16 | 2022-01-07 | 中国电子产品可靠性与环境试验研究所（（工业和信息化部电子第五研究所）（中国赛宝实验室）） | Electrode sensor and preparation method, detection system and detection method thereof |
| CN114113236A (en) * | 2021-11-10 | 2022-03-01 | 北京惠朗时代科技有限公司 | Hydrogen concentration measurement sensor and measurement system |
| CN115436436A (en) * | 2022-11-03 | 2022-12-06 | 南京元感微电子有限公司 | FET gas sensor and processing method thereof |
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Application publication date: 20210406 |