Metal Oxide Semiconductor P-n Heterojunction Ethanol Miniature Sensor Based On MEMS Technology

With the development of industry and the improvement of people’s requirements,gas sensors are widely used in daily life.The research on traditional metal sensors has been very comprehensive,but traditional sensors have also exposed many problems:such as device consistency,manufacturing efficiency and high energy consumption caused by high operating temperature.In order to solve these problems,new sensors created with the help of microelectromechanical system(MEMS)processing technology were born.However,the research on new sensors is not perfect;the limitations of material and structure still restrict the development of new sensors.This paper will seek a breakthrough for the development of sensors.Firstly,this paper successfully doped Pd into SnO2-NiO thin film through co-sputtering technology and integrated it on the MEMS micro-heating plate.The Pd-doped SnO2-NiO sensing film not only has an average response of 12 to 50 ppm ethanol(significantly higher than SnO2-NiO and Pd/SnO2 sensing films),but also has a much higher selectivity.The increase in sensitivity and selectivity is due to the design of the heterojunction in the sensing material(Schottky barrier and p-n heterojunction)and the catalytic effect of Pd on ethanol oxidation.In addition,the Pd/SnO2-NiO sensor has good consistency(＜15%),high stability and a wide operating temperature range(325-400℃).Our work not only uses complete MEMS technology to manufacture miniature gas sensors,but also greatly enriches the material selection of MEMS sensors by co-sputtering,and broadens the ideas for the development of MEMS sensors.For the problem of single structure of MEMS sensor,this paper uses self-assembly and plasma etching to prepare polystyrene microsphere(PS)array template,and uses MEMS process(magnetron sputtering,Lithography etc.)successfully prepared SnO2-NiO cross-linked network sensor.Compared with the pure SnO2-NiO film,this sensor shows a huge performance improvement at 300℃,the response to 50 ppm ethanol exceeds 10,and has good selectivity.Moreover,it showed good linearity in the continuous testing of different concentrations of ethanol,which also laid the foundation for the subsequent diversified research of MEMS sensors.