MEMS carbon monoxide sensor and preparation method and application thereof

Abstract

The invention belongs to the field of carbon monoxide detection, and particularly discloses an MEMS carbon monoxide sensor and a preparation method and application thereof. The MEMS carbon monoxide sensor comprises an MEMS substrate, and a functional composite sensitive film layer formed by an In2O3 layer, an In2O3 + NiO composite layer and an Au catalyst layer which are sequentially sputtered on the MEMS substrate. Through the In2O3 / NiO p-n heterojunction design, the Au nano island catalyst layer and the like, the manufactured MEMS carbon monoxide sensor has the advantages of being low in carbon monoxide detection limit, rapid in response, high in anti-interference capacity and the like, and meanwhile the effects of miniaturization, low cost, light weight, low power consumption, high integration degree and the like are achieved; the method has a great application prospect in the field of carbon monoxide monitoring and early warning.

Description

Technical Field

[0001] This application belongs to the field of carbon monoxide detection, specifically relating to a MEMS carbon monoxide sensor, its fabrication method, and its application. Background Technology

[0002] Carbon monoxide (CO) is a colorless, odorless, and non-irritating toxic gas closely related to numerous industrial processes, energy use, and daily life worldwide. It is commonly found as a product of the incomplete combustion of carbon-containing fuels, affecting industries such as steel metallurgy, thermal power generation, vehicle exhaust emissions, household gas appliances (such as stoves, water heaters, and heaters), and fire scenes. Although carbon monoxide is used in certain industrial processes (such as chemical synthesis), its harm to the human body is extremely significant. Carbon monoxide readily binds to hemoglobin in the blood to form carboxyhemoglobin, hindering oxygen transport and leading to tissue hypoxia and even fatal poisoning (commonly known as "carbon monoxide poisoning"). Even long-term exposure at low concentrations can cause chronic health problems. Therefore, safety is an absolute priority in places and environments involving carbon monoxide generation. Leaked or accumulated carbon monoxide is difficult to detect by human senses, and its potential poisoning risk is extremely high, making reliable carbon monoxide detection and monitoring systems essential for ensuring life safety. In scenarios such as homes, underground parking lots, tunnels, industrial production workshops, and locations where combustion equipment operates, timely and accurate detection of carbon monoxide concentration is crucial. Carbon monoxide sensors can continuously or in real-time monitor the concentration level in the air. Once the concentration exceeds a safe threshold, they immediately trigger alarms or activate safety measures, buying valuable time for evacuation or risk mitigation.

[0003] Currently, the mainstream carbon monoxide monitoring technologies mainly include the following types: electrochemical sensors, metal oxide semiconductor sensors (MOS), infrared absorption sensors, and catalytic combustion sensors (Pellistors). Among them, the lifespan of electrochemical sensors may be affected by environmental factors (such as extreme temperatures, humidity, and specific pollutants), sometimes requiring periodic calibration or replacement. Infrared absorption sensors are relatively expensive, and their optical components are sensitive to environmental dust and moisture, potentially requiring regular cleaning and maintenance. Catalytic combustion sensors (Pellistors) were widely used in the past, but when used for carbon monoxide, their specificity is insufficient, easily affected by other combustibles, and the catalyst may be at risk of "poisoning" and failure (e.g., inhibited by silicon-containing compounds or sulfides), and may be damaged at high concentrations. Metal oxide semiconductor sensors (MOS) are based on the change in material resistance caused by the adsorption reaction of carbon monoxide on the surface of the sensitive material. They typically have low power consumption and relatively low cost, and are commonly found in home alarms. However, current MOS sensors are sensitive to temperature and humidity changes, generally have poor selectivity (susceptible to interference from reducing gases such as alcohol and hydrogen), require preheating, and may require subsequent compensation algorithms to optimize performance.

[0004] Therefore, there is an urgent need for a new type of carbon monoxide sensor. Summary of the Invention

[0005] The purpose of this application is to address at least one deficiency in the prior art and to provide a carbon monoxide sensor based on a MEMS microstructure and its fabrication method, which features miniaturization, low cost, lightweight, low power consumption, high integration, low carbon monoxide detection limit, and fast response.

[0006] Based on this, the first aspect of this application provides a MEMS carbon monoxide sensor, including a sensor material, the sensor material including a MEMS substrate and a functionalized composite sensitive film layer on the MEMS substrate, the functionalized composite sensitive film layer including an In2O3 layer, a composite layer and an Au catalytic layer from bottom to top, the composite layer including In2O3 and NiO.

[0007] The aforementioned composite layer was obtained by co-sputtering and simultaneously depositing an In₂O₃ target and a NiO target, with a sputtering power ratio of (1-5):1. The composite ratio was controlled by adjusting the sputtering power ratio, resulting in a molar ratio of In₂O₃ to NiO of (2-10):1. Since indium oxide (In₂O₃) is an n-type semiconductor (band gap approximately 3.6 eV) and nickel oxide (NiO) is a p-type semiconductor (band gap approximately 3.7 eV), their composite formation of a pn heterojunction significantly increases the width of the depletion layer, improves the initial resistivity of the material, and thus enhances its sensitivity to carbon monoxide. However, an excessively high NiO ratio will lead to a change in the overall conductivity of the composite layer and a decrease in its sensitivity.

[0008] The aforementioned Au catalyst layer possesses a nanoparticle island structure, which is obtained by sputtering an Au target at a first time interval of 10 s–60 s. This application forms a nanoparticle island structure through short-time sputtering (10 s–60 s) in a pure argon atmosphere. This structure exhibits strong catalytic oxidation activity for carbon monoxide (2CO + O2 → 2CO2), effectively improving sensor selectivity and response amplitude.

[0009] This application utilizes an In2O3 / NiO pn heterojunction design to significantly broaden the interfacial depletion layer (more than 3 times that of traditional monolayer films), enabling the sensor to achieve a carbon monoxide detection limit as low as 1 ppm-50 ppm at room temperature, with a response value (S=R_a / R_g) improvement of >5 times. The Au nanoisland catalytic layer precisely catalyzes the CO surface oxidation reaction, improving the selectivity coefficients (CO / CH4, CO / H2) by ≥10 times and exhibiting outstanding resistance to cross-interference. The ultrathin nanostructured film layer (total thickness ≤500 nm) combined with an ordered bandgap matching design results in an extremely short gas diffusion path: response time (T... 90 The recovery time is shortened to 3-8 seconds, and the recovery time (T_rec) is ≤15 seconds (@100 ppmCO), far exceeding that of traditional thick-film sensors (typically T_rec). 90 >30 s).

[0010] Furthermore, this application employs noble metal modification, which can further optimize the performance of metal oxides through electronic and chemical sensitization. Specifically, since the work function of noble metals is typically greater than that of n-type metal oxides (such as In₂O₃ and ZnO), electrons transfer from the metal oxide to the noble metal upon contact, forming a Schottky barrier and a wider electron depletion layer at the interface. This depletion layer significantly modulates the conductivity of the metal oxide; the change in the depletion layer is more pronounced upon contact with the target gas, thereby amplifying the sensor's response signal. Additionally, noble metal nanoparticles, as highly efficient active sites, can activate oxygen molecules, causing them to dissociate and generate highly reactive chemically adsorbed oxygen species (such as O₂). 2- O- These activated oxygen species can then migrate ("spill over") onto the surface of adjacent metal oxides, greatly increasing the number of reaction sites. When the target gas molecules arrive, they can react with more adsorbed oxygen, thus significantly improving the response value and response rate. Simultaneously, the metal oxides also act as a carrier and stabilizer; the metal oxide substrate is not only a sensitive material but also a supporting structure, helping to disperse and stabilize noble metal nanoparticles and prevent their aggregation and deactivation. Some metal oxides themselves also possess catalytic activity and can produce synergistic catalytic effects with noble metals.

[0011] The thickness of the In2O3 layer is 100 nm-300 nm. The thickness of the composite layer is 20 nm-100 nm; if it is too thin (<20 nm), the heterojunction effect is insufficient, and the sensitivity improvement is limited; if it is too thick (>100 nm), the gas diffusion path is prolonged, resulting in slow response recovery. The thickness of the Au catalyst layer is 0.5 nm-5 nm; if it is too thin (<0.5 nm), there are insufficient catalytic active sites, and the sensitivity improvement is limited; if it is too thick (>5 nm), a continuous conductive layer will be formed, which will block the active sites on the oxide surface and thus reduce the sensitivity.

[0012] In some embodiments, the above-mentioned MEMS carbon monoxide sensor further includes a base plate, on which four circuit wire terminals are respectively provided at the four corners. The sensor material is located in the middle of the base plate and is connected to the circuit wire terminals.

[0013] The second aspect of this application provides a method for fabricating the aforementioned MEMS carbon monoxide sensor, comprising the following steps: sequentially sputtering and depositing the aforementioned In2O3 layer, the aforementioned composite layer, and the aforementioned Au catalyst layer on the aforementioned MEMS substrate. Subsequent in-situ annealing is performed, including annealing at 300 ℃-350 ℃ for 30 min-50 min under a N2 atmosphere; this in-situ annealing further optimizes the crystallinity of the film layers and the heterojunction interface characteristics. After the in-situ annealing, alloy wires are bonded (using an ultrasonic bonding machine), and the substrate is encapsulated. Before sputtering, a pretreatment step of the aforementioned MEMS substrate may also be included, specifically including cleaning with O3 plasma for 5 min-30 min to remove organic contaminants and enhance surface adhesion.

[0014] In the above preparation methods, during the sputtering deposition of the In2O3 layer, a high-purity In2O3 target is used, the gas atmosphere is a mixture of argon and oxygen (volume ratio 9:1), the sputtering power is 100 W-200 W, and the pressure is 0.3 Pa-5.0 Pa. During the sputtering deposition of the composite layer, the gas atmosphere is a mixture of argon and oxygen, the pressure is 0.3 Pa-5.0 Pa, the sputtering power of the In2O3 target is 100 W-300 W, and the sputtering power of the NiO target is 50 W-200 W. During the sputtering deposition of the Au catalyst layer, the gas atmosphere is argon, the pressure is 1.0 Pa-5.0 Pa, and the sputtering power is 50 W-200 W.

[0015] The specific process of the above-mentioned stepped sputtering deposition is as follows: a) In2O3 layer deposition: Loading an In2O3 target, pre-evacuating the chamber to 5 × 10⁻⁶ -4 Pa, introduce Ar / O2 mixed gas (flow ratio 45 sccm: 5 sccm), adjust the pressure to 0.3 Pa-5.0 Pa, apply RF power of 50 W-300 W for sputtering, and control the time according to the target thickness (approximately 15 min-35 min).

[0016] b) In2O3 / NiO composite layer deposition: Simultaneously turn on the In2O3 target (RF) and the NiO target (DC). Set the In2O3 target power to 100 W-300 W and the NiO target power to 50 W-200 W, with the same atmosphere (Ar / O2) and pressure, and the sputtering time to approximately 5 min-50 min.

[0017] c) Au catalyst layer deposition: Replace the Au target (DC), maintain a pure Ar atmosphere (50 sccm) in the chamber, and apply a low DC power of 50 W-200 W for a sputtering time of 10 s-60 s. This application achieves all-solid-state thin-film integration through magnetron sputtering, reducing the device size by 80% compared to sensors fabricated using solution methods, and is compatible with miniaturized MEMS hotplates (<1×1 mm). 2 Operating power consumption ≤30 mW (@350 ℃). Eliminating the drying and sintering steps of traditional processes reduces energy consumption by 60%. Dense sputtered thin film inhibits environmental corrosion: performance degradation <5% in a high humidity environment of 85%RH, and response drift <8% after 3000 hours of continuous operation. The Au catalyst layer exhibits excellent resistance to sulfur poisoning, maintaining 90% of its initial activity in an environment of 1 ppm H2S.

[0018] The beneficial effects of this application are as follows: By designing an In2O3 / NiO pn heterojunction and setting up an Au nano-island catalytic layer, the MEMS carbon monoxide sensor prepared in this application has the characteristics of low carbon monoxide detection limit, fast response and strong anti-interference ability. At the same time, it also achieves miniaturization, low cost, lightweight, low power consumption and high degree of integration, and has great application prospects in the field of carbon monoxide monitoring and early warning. Attached Figure Description

[0019] Figure 1 The diagram shows the structure of the sensor material of the MEMS carbon monoxide sensor in the embodiment; 1 is the MEMS substrate, 2 is the In2O3 layer, 3 is the composite layer, and 4 is the Au catalyst layer. Figure 2 The image shown is a schematic optical photograph of the MEMS carbon monoxide sensor in the embodiment. Figure 3 The figure shows the response curves of the MEMS carbon monoxide sensor in the embodiment when exposed to different concentrations of carbon monoxide atmosphere at room temperature. Figure 4 The figure shown is a comparison of the response of the MEMS carbon monoxide sensor in the embodiment to different gas atmospheres with different concentrations. Figure 5 The figure shown is a long-term stability graph of the MEMS carbon monoxide sensor in the embodiment. Figure 6 The figure shown is a repeatability result diagram of the MEMS carbon monoxide sensor in the embodiment. Figure 7 The figure shown is the silicon poisoning resistance test response diagram of the MEMS carbon monoxide sensor in the embodiment. Figure 8 The figure shown is a batch consistency result diagram of the MEMS carbon monoxide sensor in the embodiment. Figure 9 The figure shown is a comparison of the response of the MEMS carbon monoxide sensor in Comparative Example 1 when exposed to different gas atmospheres of different concentrations. Figure 10 The image shows the response of the MEMS carbon monoxide sensor in Comparative Example 1 at 100 ppm carbon monoxide. Figure 11 The figure shown is a comparison of the response of the MEMS carbon monoxide sensor in Comparative Example 2 when exposed to different gas atmospheres of different concentrations. Figure 12 The image shows the response of the MEMS carbon monoxide sensor in Comparative Example 2 at 100 ppm carbon monoxide. Detailed Implementation

[0020] The following will provide a clear and complete description of the concept and technical effects of this application in conjunction with the embodiments and accompanying drawings, so as to fully understand the purpose, solution and effects of this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0021] Example 1 A ppm-level MEMS carbon monoxide sensor includes a sensor material comprising a MEMS substrate and a functionalized composite sensitive film layer on the MEMS substrate. The functionalized composite sensitive film layer, from bottom to top, comprises an In₂O₃ layer (200 nm thick), a composite layer (50 nm thick), and an Au catalytic layer (1 nm thick). The composite layer comprises In₂O₃ and NiO. A schematic diagram of its structure is shown below. Figure 1 As shown.

[0022] It also includes a base plate, with four circuit wire terminals located at each of the four corners. The sensor material is located in the center of the base plate and is connected to the circuit wire terminals. A schematic optical photograph of the MEMS carbon monoxide sensor in this embodiment is shown below. Figure 2 As shown, the sensor has a small volume, measuring 1 mm x 1 mm and with a height of 0.5 mm.

[0023] The fabrication method of the MEMS carbon monoxide sensor in this embodiment includes the following steps: 1) Perform O3 plasma cleaning on the MEMS substrate micro hot plate for 5 min to remove organic contaminants and enhance surface adhesion.

[0024] 2) Load the In2O3 target and pre-evacuate the chamber to 5×10⁻⁶. -4 Pa, introduce Ar / O2 mixed gas (flow ratio 45 sccm: 5 sccm), adjust the pressure to 0.5 Pa, apply RF power of 150 W for sputtering, time 15 min.

[0025] 3) Simultaneously turn on the In2O3 target (RF) and the NiO target (DC). Set the In2O3 target power to 120 W, the NiO target power to 70 W, the same atmosphere (Ar / O2) and pressure, and the sputtering time to 15 min.

[0026] 4) Au target (DC), pure Ar atmosphere in the chamber (50 sccm), pressure 1.0 Pa. Apply low DC power of 50 W, and strictly control the sputtering time to 30 s.

[0027] 5) After all film layers are sputtered, anneal at 300 °C for 30 min under N2 atmosphere to optimize the film layer crystal quality and heterojunction interface characteristics.

[0028] 6) Then, using an ultrasonic bonding machine, gold wire is bonded and packaged into a sensor.

[0029] The performance of the MEMS carbon monoxide sensor fabricated in this embodiment was tested, wherein... Figure 3 This is a response curve of the carbon monoxide sensor in this embodiment exposed to different concentrations of carbon monoxide at room temperature. As shown in the figure, the test concentration ranges from 10 ppm to 25 ppm. Higher hydrogen concentrations result in lower sensor resistance, and the sensor's resolution can reach 5 ppm.

[0030] Figure 4 This is a comparison graph showing the response of the carbon monoxide sensor in this embodiment to different gas atmospheres at room temperature with varying concentrations. As can be seen from the graph, five gases—hydrogen, ammonia, ethanol, carbon monoxide, and methane—were tested at concentrations ranging from 0 ppm to 100 ppm. The sensor exhibited good selectivity for carbon monoxide.

[0031] Figure 5 This is a long-term stability graph of the carbon monoxide sensor in this embodiment. As shown in the graph, the sensor maintained 90% of its response to 100 ppm carbon monoxide over 6 months, demonstrating good long-term stability.

[0032] Figure 6 This is a repeatability result graph for the carbon monoxide sensor in this embodiment. As shown in the graph, the sensor's five-times repeatability response error for 200 ppm carbon monoxide is less than 5%.

[0033] Figure 7 This is the response graph of the carbon monoxide sensor in this embodiment for silicon poisoning resistance test. As shown in the graph, the sensor was tested for silicon poisoning resistance at 20 ppm hexamethyldisiloxane for 40 hours. The error in the response value before and after the test was less than 20%, indicating good silicon poisoning resistance.

[0034] Figure 8 This figure shows the batch consistency results of the carbon monoxide sensors in this embodiment. As can be seen from the figure, 70 unselected carbon monoxide sensors were tested, and the batch deviation of the sensors was less than 5%, indicating good consistency.

[0035] Example 2 A ppm-level MEMS carbon monoxide sensor includes a sensor material comprising a MEMS substrate and a functionalized composite sensitive film layer on the MEMS substrate. The functionalized composite sensitive film layer comprises, from bottom to top, an In2O3 layer, a composite layer, and an Au catalytic layer. The composite layer comprises In2O3 and NiO.

[0036] It also includes a base plate, with four circuit wire terminals at the four corners of the base plate. The sensor material is located in the middle of the base plate and is connected to the circuit wire terminals.

[0037] The fabrication method of the MEMS carbon monoxide sensor in this embodiment includes the following steps: 1) Perform O3 plasma cleaning on the MEMS substrate micro hot plate for 10 min to remove organic contaminants and enhance surface adhesion.

[0038] 2) Load the In2O3 target and pre-evacuate the chamber to 5×10⁻⁶. -4 Pa, introduce Ar / O2 mixed gas (flow ratio 45 sccm: 5 sccm), adjust the pressure to 1 Pa, apply RF power of 100 W for sputtering, time 30 min.

[0039] 3) Simultaneously turn on the In2O3 target (RF) and the NiO target (DC). Set the In2O3 target power to 150 W and the NiO target power to 100 W, with the same atmosphere (Ar / O2) and pressure, and a sputtering time of 20 min.

[0040] 4) Au target (DC), pure Ar atmosphere in the chamber (50 sccm), pressure 1.0 Pa. Apply low DC power of 100 W, and strictly control the sputtering time to 30 s.

[0041] 5) After all film layers are sputtered, anneal at 300 °C for 50 min under N2 atmosphere to optimize the film layer crystal quality and heterojunction interface characteristics.

[0042] 6) Then, using an ultrasonic bonding machine, gold wire is bonded and packaged into a sensor.

[0043] Example 3 A ppm-level MEMS carbon monoxide sensor includes a sensor material comprising a MEMS substrate and a functionalized composite sensitive film layer on the MEMS substrate. The functionalized composite sensitive film layer comprises, from bottom to top, an In2O3 layer, a composite layer, and an Au catalytic layer. The composite layer comprises In2O3 and NiO.

[0044] It also includes a base plate, with four circuit wire terminals at the four corners of the base plate. The sensor material is located in the middle of the base plate and is connected to the circuit wire terminals.

[0045] The fabrication method of the MEMS carbon monoxide sensor in this embodiment includes the following steps: 1) Perform O3 plasma cleaning on the MEMS substrate micro hot plate for 30 min to remove organic contaminants and enhance surface adhesion.

[0046] 2) Load the In2O3 target and pre-evacuate the chamber to 5×10⁻⁶. -4Pa, introduce Ar / O2 mixed gas (flow ratio 45 sccm: 5 sccm), adjust the pressure to 1.5 Pa, apply RF power of 200 W for sputtering, time 20 min.

[0047] 3) Simultaneously turn on the In2O3 target (RF) and the NiO target (DC). Set the In2O3 target power to 120 W, the NiO target power to 60 W, the same atmosphere (Ar / O2) and pressure, and the sputtering time to 40 min.

[0048] 4) Au target (DC), pure Ar atmosphere in the chamber (50 sccm), pressure 1.0 Pa. Apply low DC power of 50 W, and strictly control the sputtering time to 30 s.

[0049] 5) After all film layers are sputtered, anneal at 300 °C for 30 min under N2 atmosphere to optimize the film layer crystal quality and heterojunction interface characteristics.

[0050] 6) Then, using an ultrasonic bonding machine, gold wire is bonded and packaged into a sensor.

[0051] Comparative Example 1 Meanwhile, in order to compare the effects of different heterojunction doping on the performance of the sensitive film, this comparative example provides a MEMS carbon monoxide sensor, including a sensor material, which includes a MEMS substrate and a functionalized composite sensitive film on the MEMS substrate. The functionalized composite sensitive film includes, from bottom to top, an In2O3 layer, a composite layer and an Au catalytic layer. The composite layer includes In2O3 and TiO2.

[0052] It also includes a base plate, with four circuit wire terminals at the four corners of the base plate. The sensor material is located in the middle of the base plate and is connected to the circuit wire terminals.

[0053] The fabrication method of the MEMS carbon monoxide sensor in this comparative example includes the following steps: 1) Perform O3 plasma cleaning on the MEMS substrate micro hot plate for 5 min to remove organic contaminants and enhance surface adhesion.

[0054] 2) Load the In2O3 target and pre-evacuate the chamber to 5×10⁻⁶. -4 Pa, introduce Ar / O2 mixed gas (flow ratio 45 sccm: 5 sccm), adjust the pressure to 0.5 Pa, apply RF power of 150 W for sputtering, time 15 min.

[0055] 3) Simultaneously turn on the In2O3 target (RF) and TiO2 target (DC). Set the In2O3 target power to 120 W, the TiO2 target power to 70 W, the same atmosphere (Ar / O2) and pressure, and the sputtering time to 15 min.

[0056] 4) Au target (DC), pure Ar atmosphere in the chamber (50 sccm), pressure 1.0 Pa. Apply low DC power of 50 W, and strictly control the sputtering time to 30 s.

[0057] 5) After all film layers are sputtered, anneal at 300 °C for 30 min under N2 atmosphere to optimize the film layer crystal quality and heterojunction interface characteristics.

[0058] 6) Then, using an ultrasonic bonding machine, gold wire is bonded and packaged into a sensor.

[0059] Comparative Example 2 Meanwhile, in order to compare the effects of different heterojunction doping on the performance of the sensitive film, this comparative example provides a MEMS carbon monoxide sensor, including a sensor material, which includes a MEMS substrate and a functionalized composite sensitive film on the MEMS substrate. The functionalized composite sensitive film includes, from bottom to top, a SnO2 layer, a composite layer and an Au catalytic layer. The composite layer includes SnO2 and NiO.

[0060] It also includes a base plate, with four circuit wire terminals at the four corners of the base plate. The sensor material is located in the middle of the base plate and is connected to the circuit wire terminals.

[0061] The fabrication method of the MEMS carbon monoxide sensor in this comparative example includes the following steps: 1) Perform O3 plasma cleaning on the MEMS substrate micro hot plate for 5 min to remove organic contaminants and enhance surface adhesion.

[0062] 2) Load the SnO2 target and pre-evacuate the chamber to 5×10⁻⁶. -4 Pa, introduce Ar / O2 mixed gas (flow ratio 45 sccm: 5 sccm), adjust the pressure to 0.5 Pa, apply RF power of 150 W for sputtering, time 15 min.

[0063] 3) Simultaneously turn on the SnO2 target (RF) and NiO target (DC). Set the SnO2 target power to 120 W, the NiO target power to 70 W, the same atmosphere (Ar / O2) and pressure, and the sputtering time to 15 min.

[0064] 4) Au target (DC), pure Ar atmosphere in the chamber (50 sccm), pressure 1.0 Pa. Apply low DC power of 50 W, and strictly control the sputtering time to 30 s.

[0065] 5) After all film layers are sputtered, anneal at 300 °C for 30 min under N2 atmosphere to optimize the film layer crystal quality and heterojunction interface characteristics.

[0066] 6) Then, using an ultrasonic bonding machine, gold wire is bonded and packaged into a sensor.

[0067] Carbon monoxide detection was performed using the sensor in Comparative Example 1, and the results are as follows: Figure 9 As shown, sensors fabricated using In2O3 and TiO2 heterojunction materials exhibit relatively poor selectivity. Figure 10 Tests showed that the sensor responded to 100 ppm carbon monoxide with a value of 1.03, which is significantly lower than the response of the sensor in Example 1.

[0068] Carbon monoxide detection was performed on the sensor used in Example 2, and the results are as follows: Figure 11 As shown, sensors fabricated using different heterojunction materials, SnO2 and NiO, exhibit relatively poor selectivity, but show higher response to hydrogen sulfide. Figure 12 Tests showed that the sensor responded to 200 ppm carbon monoxide with a value of 1.1, which was significantly lower than the response of the sensor in Example 1.

[0069] The above description is merely a preferred embodiment of this application. This application is not limited to the above-described embodiments. Any embodiment that achieves the technical effect of this application using the same means should fall within the protection scope of this application. Within the protection scope of this application, the technical solutions and / or implementation methods can have various modifications and variations.

Claims

1. A MEMS carbon monoxide sensor, characterized by, The sensor material comprises a MEMS substrate and a functionalized composite sensitive film layer on the MEMS substrate, the functionalized composite sensitive film layer comprises, from bottom to top, an In2O3 layer, a composite layer and an Au catalytic layer, and the composite layer comprises In2O3 and NiO.

2. The MEMS carbon monoxide sensor of claim 1, wherein, The molar ratio of In2O3 to NiO in the composite layer is (2-10):

1.

3. The MEMS carbon monoxide sensor of claim 1, wherein, The Au catalytic layer has a nanoparticle island structure.

4. The MEMS carbon monoxide sensor of claim 1, wherein, The thickness of the In2O3 layer is 100 nm-300 nm; and / or, the thickness of the composite layer is 20 nm-100 nm; and / or, the thickness of the Au catalytic layer is 0.5 nm-5 nm.

5. The MEMS carbon monoxide sensor of claim 1, wherein, The MEMS carbon monoxide sensor further comprises a bottom plate, four circuit line terminals are respectively arranged at the four corners of the bottom plate, and the sensor material is arranged at the middle of the bottom plate and connected with the circuit line terminals.

6. A method of manufacturing the MEMS carbon monoxide sensor according to any one of claims 1 to 5, characterized by, The method comprises the following steps: The In2O3 layer, the composite layer and the Au catalytic layer are sequentially formed on the MEMS substrate by sputtering deposition.

7. The production method according to claim 6, characterized by, After the In2O3 layer, the composite layer and the Au catalytic layer are sequentially formed on the MEMS substrate by sputtering deposition, in-situ annealing treatment is further performed, and the process of the in-situ annealing treatment comprises: maintaining 300 ℃-350 ℃ annealing for 30 min-50 min under N2 atmosphere.

8. The preparation method according to claim 7, characterized in that, After the in-situ annealing treatment, gold wire bonding and packaging are performed.

9. The preparation method according to claim 6, characterized in that, In the process of sputtering deposition of the In2O3 layer, the gas atmosphere is a mixed gas of argon and oxygen, the sputtering power is 100 W-200 W, and the pressure is 0.3 Pa-5.0 Pa; and / or, in the process of sputtering deposition of the composite layer, the gas atmosphere is a mixed gas of argon and oxygen, the pressure is 0.3 Pa-5.0 Pa, the sputtering power of the In2O3 target is 100 W-300 W, and the sputtering power of the NiO target is 50 W-200 W; and / or, in the process of sputtering deposition of the Au catalytic layer, the gas atmosphere is argon, the pressure is 1.0 Pa-5.0 Pa, and the sputtering power is 50 W-200 W.

10. Use of the MEMS carbon monoxide sensor according to any one of claims 1 to 5 in a monitoring device or an alarm device.

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