Study Of Silicon-based MEMS Gas Sensor

In today's world,gas sensors have been widely used in various aspects of national production and daily life,from the detection of toxic gases,flammable and explosive gases in industrial production,to the monitoring and alarming of harmful gases in the furniture environment,and drunk driving detection etc.All of them show the unique advantages and great application prospects of gas sensors.Compared with traditional ceramic tube gas sensors,silicon-based MEMS gas sensor,manufactured by MEMS process technology,especially using metal oxide semiconductor gas sensing material have become a research focus and hotspot in the field of sensors at home and abroad because of its sensitivity,fast response,small size,low power consumption,easy integration,and strong stability,etc.In this paper,the theoretical and experimental research work of the silicon-based MEMS gas sensor using SnO₂ gas sensing material is carried out.Based on the large commercial finite element analysis software ANSYS,the theoretical model of micro-hot plate with different structures is constructed.The influences and laws of the structural parameters and material parameters of the micro-hot plate of the membrane structure and the suspended structure on the steady-state thermal effect of the micro-hot plate were systematically analyzed.The simulation results show that the temperature distribution stability and power consumption of the suspension structure of the micro-hot plate are better than that of the membrane structure micro-hot plate.The maximum temperature difference in the horizontal direction of the optimized heating platform of the suspended structure micro-hot plate is only 1.956?and the working power consumption is only 11mW.In addition,the paper proposes a new type of the suspended structure micro-hot plate with a single-layer insulation.Through the unique"wraparound"electrode design,it suppresses the short circuit problem common in the traditional single-layer insulation structure micro-hot plate,and has good thermal effect.The simulation results show that the maximum temperature difference on the heating platform of the new structure micro-hotplate is only 1.6?,and the power consumption can be as low as 8.4 mW.Based on the theoretical research results,this paper uses the MEMS manufacturing process line to carry out the fabrication of the actual silicon-based MEMS gas sensor,and successfully developed a single-layer insulation layer suspension structure micro-hot plate.The gas sensing properties of SnO₂ gas-sensitive thick film under different process conditions were studied,and the process optimization of gas-sensitive thick film was carried out.Finally,based on the experimental results,a silicon-based MEMS gas sensor using SnO₂ gas sensing material was realized.The packaged gas sensor test shows that the gas sensor can be raised to 300?operating temperature at 13mW,and exhibits good gas sensitivity at 250?and 300?,meeting the design requirements.