Analysis Of Temperature Compensation And Calibration Of Piezoresistive Pressure Sensor

The industrial production and daily life such as the development of the marine environment, the environmental pollution, the exploration of the universe, the research and development of pharmaceutical engineering, have a very large market demand on the pressure sensor. The piezoresistive pressure sensor with good stability, high sensitivity, wide frequency response range, small volume, and easy to be integrated, has become currently the fastest growing and the use of a very wide range of pressure sensors. Due to the piezoresistive pressure sensor is made according to the principle of the piezoresistive effect of the semiconductor silicon material, and semiconductor materials have very high sensitivity on the temperature, the output signal of piezoresistive pressure sensor will be subjected to temperature effect, which is called thermal drift. The sensitivity and measurement accuracy of the sensor will be seriously restricted by the thermal drift, so it is very important to compensate the thermal drift of the sensor.The main purpose of this paper is to establish the temperature compensation model by studying the physical properties of the piezoresistive pressure sensor, and then determine the dynamic behavior, so as to improve the measurement accuracy of the sensor. The main work of this paper are as follows:The principle of piezoresistive pressure sensor has been analyzed, the process flow of the sensor in the preparation process has been illustrated and the causes of thermal drift of the sensor have been analyzed in details; The stress distribution of silicon film under external pressure has been analyzed, and the analytical model of stress and strain of the elastic thin film has been obtained based on the theory of small deflection; The effect of temperature on the resistance of semiconductor materials has been analyzed, and the relationship between doping concentration and temperature coefficient of resistance has been studied. Finally, the analytical model of the resistance value related to temperature and doping concentration has been obtained; The piezoresistive coefficients of single crystal silicon has been introduced, and the influence of temperature and doping concentration on the piezoresistive coefficients has been analyzed, then the analytical model of the coefficient of pressure resistance related to temperature and doping concentration has been obtained; Based on the cause of the stress induced by packaging, the relationship between the temperature and thermal expansion coefficient of the silicon material and the substrate material has been studied. And the analytical model of the package stress on the function of the temperature has been obtained; The relationship between the Young's modulus of the silicon and the temperature has been studied, and the analytical model of the Young's modulus related to temperature is obtained; Based on the above research work, the analytical model of the temperature compensation of the sensor has been established, the performance of the sensor has been analyzed based on the sample data obtained from the experiment, and of the temperature compensation model has been verified.The results showed that when the air pressure was less than 100hPa, the maximum error was less than ±0.6hPa; and when the air pressure was larger than 100hPa, the maximum error was less than ±7hPa. The research results of this paper has certain reference value for further research on the temperature compensation of the piezoresistive pressure sensor.