Fabrication and Nitrogen Dioxide Sensing Characteristics of PbPc Thin Film Gas Sensor

A PbPc thin film gas sensor on silicon substrate was fabrication by MEMS (microelectro-mechanical systems) technologies. The principle, configuration and technological process of the sensor were described and the preparation of PbPc thin film was given. In order to reduce the power, the wafer was subjected to the silicon etching at the backside and the power is reduced to tens of milli-watt. For the support of advanced integrated circuit technique and the microelectronics industry, this MEMS gas sensitive sensor has many advantages such as small bulk and small mass, high sensitivity, quick response, low cost and so on. The sensitive characteristics of the gas sensor were studied and experiment results were confirmed by the nitrogen dioxide sensitive mechanism of the sensor. Both the resistance and sensitivity decrease when the NO₂ concentration increases and the sensitivity nearly keep a constant between 30 ppm and 70 ppm. The resistance for lower NO₂ concentration has the larger value at the same temperature and 90degC is the best working temperature to achieve the largest sensitivity. The response and recovery time is about 3 s and 6 s respectively