Preparation method of MEMS formaldehyde sensor based on aluminum-doped zinc oxide porous nano-film

A technology of aluminum-doped zinc oxide and formaldehyde sensors, which is applied in the field of formaldehyde sensors, can solve the problems of increasing process implementation, increasing film damage, increasing process steps, etc., and achieves the effects of improving test stability, improving response, and increasing contact area

Active Publication Date: 2021-01-05
XI AN JIAOTONG UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Although the structure is relatively intuitive and the heating area is concentrated in a certain area, due to the increase of process steps, it is more difficult for the later process implementation, because the use of upper and lower structures to embed the heating wire in the insulating layer will cause a very complicated stress state of the supporting film. Thereby increasing the probability of film damage, so it is particularly important to choose a suitable preparation method whether it is for quickness or future application in industrial production.

Method used

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  • Preparation method of MEMS formaldehyde sensor based on aluminum-doped zinc oxide porous nano-film
  • Preparation method of MEMS formaldehyde sensor based on aluminum-doped zinc oxide porous nano-film
  • Preparation method of MEMS formaldehyde sensor based on aluminum-doped zinc oxide porous nano-film

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Embodiment 1

[0085] (1) As shown in Figure 8(a), the first layer of SiO was prepared on the upper and lower sides of the Si substrate by thermal oxidation. 2 insulating layer and the first layer of SiO 2 masking layer, in the first layer SiO 2 insulating layer and the first layer of SiO 2 The first layer of Si was prepared respectively on the masking layer 3 N 4 insulating layer and Si 3 N 4 masking layer, where SiO 2 layer film thickness is 500nm, Si 3 N 4 The thickness of the layer is 150 nm.

[0086] (2) As shown in Figure 8(b), in the first layer of Si 3 N 4 The second layer of SiO was sequentially prepared on the insulating layer 2 insulating layer and second layer Si 3 N 4 Insulation layer, put the silicon wafer into the tube annealing furnace, set the temperature at 500°C, and pass 100% N for 1 hour first 2 , followed by 5 hours of 6% O 2 , ultimatum 1 hour 100% N 2 Anneal for 5 hours.

[0087] (3) As shown in Figure 8(c), the second layer of Si on the front support...

Embodiment 2

[0103] (1) As shown in Figure 8(a), the first layer of SiO was prepared on the upper and lower sides of the Si substrate by thermal oxidation. 2 insulating layer and the first layer of SiO 2 masking layer, in the first layer SiO 2 insulating layer and the first layer of SiO 2 The first layer of Si was prepared respectively on the masking layer 3 N 4 insulating layer and Si 3 N 4 masking layer, forming SiO 2 -Si 3 N 4 The front support layer film and the back mask layer film; where SiO 2 layer film thickness is 490nm, Si 3 N 4 The thickness of the layer is 140 nm.

[0104] (2) As shown in Figure 8(b), in the first layer of Si 3 N 4 The second layer of SiO was sequentially prepared on the insulating layer 2 insulating layer and second layer Si 3 N 4 Insulation layer, put the silicon wafer into the tube annealing furnace, set the temperature at 600°C, and pass 100% N for 1 hour first 2 , followed by 3 hours of 5% O 2 , ultimatum 1 hour 100% N 2 Anneal for 7 hou...

Embodiment 3

[0121] (1) As shown in Figure 8(a), the first layer of SiO was prepared on the upper and lower sides of the Si substrate by thermal oxidation. 2 insulating layer and the first layer of SiO 2 masking layer, in the first layer SiO 2 insulating layer and the first layer of SiO 2 The first layer of Si was prepared respectively on the masking layer 3 N 4 insulating layer and Si 3 N 4 masking layer, forming SiO 2 -Si 3 N 4 The front support layer film and the back mask layer film; where SiO 2 Layer film thickness is 510nm, Si 3 N 4 The thickness of the layer is 160 nm.

[0122] (2) As shown in Figure 8(b), in the first layer of Si3 N 4 The second layer of SiO was sequentially prepared on the insulating layer 2 insulating layer and second layer Si 3 N 4 Insulation layer, put the silicon wafer into the tube annealing furnace, set the temperature at 550°C, and pass 100% N for 1 hour first 2 , followed by 5 hours of 5% O 2 , ultimatum 1 hour 100% N 2 Anneal for 5 hours...

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Abstract

The invention discloses a preparation method of an MEMS (Micro-electromechanical Systems) formaldehyde sensor based on an aluminum-doped zinc oxide porous nano-film. The sensor comprises a SiO2-Si3N4masking layer, a Si substrate, an insulating layer, a heating electrode, a sensitive electrode, a temperature measuring electrode, a sensitive material and a noble metal doping agent from bottom to top, wherein the SiO2-Si3N4 masking layer and the Si substrate are superposed by double layers of SiO2-Si3N4. Polystyrene microspheres are used as a masking layer, oxygen plasma etching is used for adjusting the diameters of the microspheres, magnetron co-sputtering ZnO and Al2O3 is used for depositing a composite sensitive film in gaps of the microspheres with reduced diameters, and the purpose ofadjusting the microstructure of the composite film is achieved by adjusting the sputtering power, time, substrate temperature and sputtering pressure in the ZnO and Al2O3 sputtering process. Pd precious metal is adopted for doping and surface modification of the aluminum-doped zinc oxide film, adsorption and desorption of gas and an interface are accelerated, the gas sensitivity of the sensor is improved, the specific surface area of the film is increased, and the response of the gas sensor is improved.

Description

technical field [0001] The invention relates to a formaldehyde sensor, in particular to a method for preparing a MEMS formaldehyde sensor based on aluminum-doped zinc oxide porous nano film. Background technique [0002] Formaldehyde is a colorless, flammable chemical with reducing and pungent odors, and human exposure to formaldehyde can affect the immune system response. It is a human carcinogen and can cause blood cancer, lymphoma and nasopharyngeal cancer. If the exposure of formaldehyde exceeds the allowable exposure limit, it will cause very large irritation to the nose, eyes and throat of the human body. The World Health Organization recommends that the safe limit for formaldehyde is an exposure of 2ppm within 8 hours, and that indoor levels should not exceed 80ppb within 30 minutes. Therefore, the development of high-performance formaldehyde sensors is particularly important for environmental safety and human health. Formaldehyde exposures above 3 ppm can induce c...

Claims

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Application Information

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IPC IPC(8): G01N27/12B81B7/02B82Y15/00B82Y40/00
CPCB81B7/02B82Y15/00B82Y40/00G01N27/124G01N27/128
Inventor 张铭王久洪唐闫焜王海容
Owner XI AN JIAOTONG UNIV
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