CN115287589B - Preparation method and application of gas sensor based on curled silicon nano film - Google Patents

Abstract

The invention belongs to the technical field of gas sensors, and relates to a preparation method and application of a gas sensor based on a curled silicon nano film, wherein an Si sensitive film grows on a glass substrate through an electron beam evaporation deposition technology, the Si sensitive film is curled through a proper method to form a film coil, then the film coil is manufactured into the gas sensor for detecting nitrogen dioxide gas, and the film with gas sensitivity is converted into a three-dimensional film coil device from a two-dimensional planar device, so that the specific surface area of the device is greatly improved, the film thickness is accurate and controllable, the film is suitable for preparing the gas sensor in batches, and the film coil has important value for development of gas sensitive materials and application of the gas sensor.

Description

Preparation method and application of gas sensor based on curled silicon nanomembrane

Technical areas:

The invention belongs to the technical field of gas sensors and relates to a preparation method and application of a gas sensor based on curled silicon nanofilm. The prepared gas sensor is used for nitrogen dioxide detection.

Background technique:

Nitrogen dioxide is an important inorganic chemical raw material, and it is also a common toxic industrial and domestic waste gas, such as motor vehicle exhaust and boiler exhaust gas emissions. It has various environmental effects, including: on wetlands and The effects of competition and compositional changes among terrestrial plant species, reduced atmospheric visibility, acidification and eutrophication of surface waters, and increased levels of toxins in water bodies that are harmful to fish and other aquatic life. Therefore, the detection of nitrogen dioxide has important application value.

Gas sensors have the advantages of small size, high sensitivity, good stability, and simple structure, and are widely used in the detection of highly hazardous gases. At present, gas sensor materials for nitrogen dioxide are mainly semiconductor metal oxides, such as In ₂ O ₃ , SnO ₂ , Fe ₂ O ₃ , etc. In order to further improve the detection sensitivity of gas sensors, researchers mostly use precious metals such as Au and Pt. etc. as sensitizers to enhance the surface sensitivity performance of metal oxide gas-sensitive materials.

However, since the thin-film gas sensor needs to be prepared based on a substrate, its effective area for gas detection will inevitably be limited. There is also an upper limit to improving its performance through material modification. And as integrated circuits have increasingly higher requirements for device miniaturization, maximizing the use of the area on the wafer has become the goal of researchers. Therefore, there is an urgent need to develop a new structure of sensitive thin film devices to solve the above problems and achieve the corresponding goals.

Contents of the invention:

The purpose of the present invention is to overcome the shortcomings of the existing technology and design and provide a large-scale preparation method and application of a gas sensor based on curled silicon nanofilm. The thickness of the curled silicon nanofilm film in the prepared gas sensor is controllable and is suitable for batch production. A gas sensor is prepared, and the effective contact area between the sensor and the gas to be measured is greatly increased.

In order to achieve the above-mentioned object of the invention, the present invention uses electron beam evaporation deposition technology to grow a Si sensitive film on a glass substrate, and curls it to form a film roll tube through an appropriate method, and then makes a gas sensor for nitrogen dioxide gas detection. Specifically, Contains the following steps:

(1) Take a circular glass substrate with a diameter of 2 inches and a thickness of 0.55mm as the substrate, and use a glue spreader to spin-coat a layer of photoresist on the surface of the substrate;

(2) Perform photolithography on the substrate obtained in step (1) to etch the sacrificial layer pattern;

(3) Use electron beam evaporation deposition to evaporate a layer of Ge thin film on the substrate obtained in step (2), remove the glue and oxidize it to obtain a substrate with a GeO sacrificial layer thin film;

(4) Use the substrate with the GeO sacrificial layer film obtained in step (3), repeat the glue coating in step (1) and the photolithography in step (2) to etch the electrode pattern;

(5) Evaporate a layer of Cr/Au thin film on the substrate obtained in step (4) using resistance thermal evaporation deposition as a device electrode;

(6) Repeat glue coating and photolithography on the substrate obtained in step (5) to etch the curled layer pattern;

(7) Evaporate a layer of Si thin film on the substrate obtained in step (6) using electron beam evaporation deposition;

(8) Soak the substrate obtained in step (7) in 30% H ₂ O ₂ solution for 12 hours, remove the GeO sacrificial layer, and roll up the Si film to form a rolled tube;

(9) Quickly transfer the substrate obtained in step (8) to a supercritical dryer, use ethanol to supercritically dry the substrate, and obtain a gas sensor based on curled silicon nanofilm.

The gas sensor based on the curled silicon nanofilm prepared by the invention can be directly used for the detection of nitrogen dioxide.

Compared with the existing planar film sensor, the present invention transforms the gas-sensitive film from a two-dimensional planar device into a three-dimensional film roll device, greatly increasing the specific surface area of the device, and the film thickness is accurately controllable, and is suitable for Preparing gas sensors in batches is of great value for the development of gas-sensitive materials and gas sensor applications.

Picture description:

Figure 1 is a design diagram of the coating pattern of the Si film roll tube prepared in the embodiment of the present invention.

Figure 2 is an optical microscope photo of the Si film roll prepared in the embodiment of the present invention.

Figure 3 is the gas-sensitive response recovery curve of the Si film roll prepared in the embodiment of the present invention to 20 ppm nitrogen dioxide at 300°C.

Detailed ways:

Further description will be given below through specific embodiments and in conjunction with the accompanying drawings.

Example:

The specific process of preparing a gas sensor based on curled silicon nanofilm in this embodiment is:

(1) Take a circular glass substrate with a diameter of 2 inches and a thickness of 0.55mm as the substrate, use the 650Mz23N glue spreader of Micron Technology Co., Ltd. to spin-coat a layer of photoresist on the surface of the substrate, and then photolithography The glue model is ROL-7133 negative photoresist of Xi'an Boyan Company. The low speed of the glue leveling machine is 600rpm and the rotation time is 6 seconds; the high speed is 2000rpm and the rotation time is 20 seconds. Then the substrate coated with photoresist is Place on an electric hot plate and bake at 110°C for 90 seconds;

(2) Use the URE-200/35 UV lithography machine of the Institute of Optoelectronics Technology, Chinese Academy of Sciences to lithograph an array consisting of a rectangular pattern with a length of 320 μm and a width of 300 μm. As shown in Figure 1, place the lithographed substrate on The electric hot plate is post-baked at 110°C for 120 seconds, then immersed in 1% NaOH solution for development for 45 seconds, washed with deionized water, and dried with nitrogen flow to obtain a substrate with a sacrificial layer pattern etched;

(3) Use the AUTO500 electron beam coating system of the British HHV company to perform electron beam evaporation deposition of Ge metal thin films: First, fix the substrate with the sacrificial layer pattern etched on the sample holder. Deposit 45nm Ge metal at a rate, then immerse the deposited substrate in an appropriate amount of acetone to dissolve the photoresist, and obtain an array of rectangular Ge films on the substrate;

(4) Use the PDC-2G-2 plasma cleaning machine of German Webster Nanosystems to clean the substrate with _O2 plasma for 5 minutes, put it into a 150°C oven for oxidation for 18 hours, and obtain a GeO sacrificial layer on the substrate film;

(5) Repeat the glue coating and pre-baking process in step (1) for the substrate obtained in step (4), and photoetch the electrode pattern on the substrate using the same method in step (2). After photolithography, the substrate Repeat the post-baking, developing, cleaning and drying steps in step (2);

(6) Use the VZZ-300 high vacuum resistance evaporation coating equipment of Beijing Micro-Nano Vacuum Company to perform resistance evaporation deposition of Au thin films: Fix the substrate obtained in step (5) on the sample holder. Deposit 10nmCr metal and 40nmAu metal at a rate, immerse the deposited substrate in an appropriate amount of acetone to dissolve the photoresist, and obtain an array of thin film electrodes;

(7) Repeat the glue coating and pre-baking process in step (1) on the substrate obtained in step (6), and use the same method in step (2) to photoetch a rectangular pattern of 300 μm and 320 μm wide on the substrate. array. After photolithography, repeat the post-baking, developing, cleaning and drying steps in step (2) on the substrate;

(8) Use the AUTO500 electron beam coating system of the British HHV company to perform electron beam evaporation deposition of Si films: Fix the substrate obtained in step (7) on the sample holder. Deposit 40nmSi at a rate. Dip the deposited substrate into an appropriate amount of acetone to dissolve the photoresist to obtain an array of rectangular Si films;

(9) Soak the substrate obtained in step (8) in 30% H ₂ O ₂ solution for 12 hours, remove the GeO sacrificial layer film, roll up the Si film to form a curled film, and then quickly transfer the substrate to Tousimis in the United States Drying is carried out in the company's SAMDRI-PVT-3D supercritical dryer. After the drying process is completed, the silicon curled film gas sensor is obtained. Its optical microscope photo is shown in Figure 2.

In this embodiment, the prepared Si curled silicon thin film gas sensor is used to detect nitrogen dioxide. Its response-recovery characteristics to nitrogen dioxide with a concentration of 20 ppm are shown in Figure 3.

Claims (2)

1. A method for preparing a gas sensor based on curled silicon nanofilm, which is characterized in that it specifically includes the following steps: (1) Take a circular glass substrate with a diameter of 2 inches and a thickness of 0.55mm as the substrate, and use a glue dispensing machine to spin-coat a layer of photoresist on the surface of the substrate. The low speed of the glue dispensing machine is 600rpm, and the rotation time is 6 seconds; the high speed is 2000rpm, the rotation time is 20 seconds, and then the substrate coated with photoresist is placed on the electric hot plate and baked at 110°C for 90 seconds; (2) Use a UV lithography machine to lithograph an array consisting of a rectangular pattern with a length of 320 μm and a width of 300 μm. Place the photolithographed substrate on an electric hot plate and post-bake it at 110°C for 120 seconds, and then immerse it in 1% NaOH. After developing in the solution for 45 seconds, it is cleaned with deionized water, and dried by nitrogen flow to obtain a substrate with a sacrificial layer pattern etched; (3) Use the electron beam coating system to perform electron beam evaporation deposition of Ge metal thin films: First, fix the substrate with the sacrificial layer pattern etched on the sample holder. Deposit 45nm Ge metal at a rate, then immerse the deposited substrate in acetone to dissolve the photoresist, and obtain an array of rectangular Ge films on the substrate; (4) Use a plasma cleaning machine to clean the substrate with _O2 plasma for 5 minutes, and place it in a 150°C oven for oxidation for 18 hours to obtain a GeO sacrificial layer film on the substrate; (5) Repeat the glue coating and pre-baking process in step (1) for the substrate obtained in step (4), and photoetch the electrode pattern on the substrate using the same method in step (2). After photolithography, the substrate Repeat the post-baking, developing, cleaning and drying steps in step (2); (6) Use high vacuum resistance evaporation coating equipment to perform resistance evaporation deposition of Au thin films: Fix the substrate obtained in step (5) on the sample holder to Deposit 10nmCr metal and 40nmAu metal at a rate, immerse the deposited substrate in acetone to dissolve the photoresist, and obtain an array of thin film electrodes; (7) Repeat the glue coating and pre-baking process in step (1) on the substrate obtained in step (6), and use the same method in step (2) to photoetch a rectangular pattern of 300 μm and 320 μm wide on the substrate. Array, after photolithography, repeat the post-baking, developing, cleaning and drying steps in step (2) on the substrate; (8) Use the electron beam coating system to perform electron beam evaporation deposition of Si thin films: Fix the substrate obtained in step (7) on the sample holder. Deposit 40nm Si at a rate, immerse the deposited substrate in an appropriate amount of acetone to dissolve the photoresist, and obtain an array of rectangular Si films; (9) Soak the substrate obtained in step (8) in 30% H ₂ O ₂ solution for 12 hours to remove the GeO sacrificial layer film, roll up the Si film to form a curled film, and then quickly transfer the substrate to the supercritical Drying is carried out in a dryer, and after drying, a silicon curled film gas sensor is obtained. 2. Application of a gas sensor based on curled silicon nanofilm prepared by the method of claim 1, characterized in that it can be directly used for the detection of nitrogen dioxide.