The Study Of Mechanism And The Design Of Oxygen Micro-Sensor Based On Mems

Oxygen sensor is a primary branch of gas sensor. Oxygen sensor has widely applied to a lot of fields,such as metallurgy,keeping-fresh of food,medical treatment,biology,environmental protection and so on. For a long period of time,the study of oxygen sensor has been very active. The methods of traditional oxygen detection can accurately analyze the concentration of oxygen,but those factors such as high cost,complicated device,long time consumption and inconvenient operation and maintenance have restricted the application of real-time monitor and control and online measure. Most optical oxygen sensors can not solve the problems of low sensitivity and poor stability. Some oxygen sensors require working at high temperature (higher than 500C-600C) . It is difficult for them to work at room temperature. In a general way,the sensitive performance of gas sensor is closely relative to the working temperature. It is very easy for MEMS to integrate the gas sensitive element,the heater and temperature sensor together. The development of MEMS provides the possibility of micromation,integration,intelligentization,multi-function of semiconductor gas sensor. And it also has very important significance to improve selectivity,reliability and stability of semiconductor gas sensor. Nowadays,there are some reports on oxygen micro-sensor based on MEMS in the references of IEEE. The following is the primary research work in this thesis.1. Based on the crystal lattice theory of coordinate chemical compound,the crystal lattice of zirconia was analyzed. Some results were obtained that adulterating zirconia with yttria,viz. Yttria-Stabilized Zirconia (YSZ),has some oxygen ion vacancies,sequentially has ionic conductivity. And the influence on YSZ ion conductivity of the different adulterated concentration of yttria was discussed.2. Based on the theory of Sol-gel,YSZ sol-gel membrane was made. And YSZ sol-gel membranes with the different zirconia concentration were tested.3. The initial model of flat capacitive oxygen sensor was proposed. Then the working mechanism of flat capacitive oxygen sensor was discussed. The experimental results show that the sensitive membrane is characterized by favorable selectivity and repetition.4. In view of micromation of sensor and MEMS fabrication processing,MOS capacitive oxygen micro-sensor was devised. According to theory of semiconductor energy band,the working principle of MOS capacitive oxygen micro-sensor was elucidated.5. Based on MOS capacitive oxygen micro-sensor,the structure of MOSFET oxygen micro-sensor was presented. The heater and temperature sensor are integrated into the device. Then the specific technological process and the masks of MOSFET oxygen micro-sensor,the heater and the temperature sensor were designed. Simulating curves indicate that MOSFET oxygen micro-sensor has the typical characteristic curves alike general MOSFETs. The minutevariety of unit area capacitance (2.0x10-7 pF/um2) can be transformed into relatively obviousvoltage signal (VTmax = 8/mV). The structure of MOSFET oxygen micro-sensor provides reference for the design of MOSFET oxygen micro-sensor for the future.