Research On A Novel Structure Mems Piezoresistive Pressure Sensor

Piezoresistive pressure sensors have been put into use for decades and are among the most successful micro-machined sensors.From their introduction in the 1960 s,they have experienced a dramatic improvement in performance,as new micro-fabrication techniques have been developed.For high-accuracy applications,there is a strong focus on the high sensitivity and linearity of the sensor output signal.This thesis focuses on the method to improve the performance of MEMS piezoresistive pressure sensors.In order to develop next generation high performance piezoresistive pressure sensor,the key design challenges relating to the sensor diaphragm must be addressed,namely sizing optimization.The configuration design of the sensor is introduced.According to the configuration design,the formulation of the diaphragm structures is discussed and then the sizing optimization is introduced.The development presented in this study provides a foundation for informed design and development of sensor diaphragms for high performance silicon piezoresistive pressure sensors.Based on the structure optimization,another major finding has been the design methodology and the fabrication process of a novel piezoresistive pressure sensor with a combined cross-beam membrane and peninsula(CBMP)diaphragm structure for micropressure measurements.The sensor is then analyzed through various experiments.Compared to other traditional diaphragm types,a significant increase in sensitivity can be obtained by the proposed sensor,and the membrane deflection and nonlinearity error considerably decrease.In temperature instability of the piezoresistive pressure sensors,the thermal effects on the output performances are studied.Influences of the environmental temperature,the residual stress on the resistance are theoretically investigated.It is shown that the output characteristics of piezoresistive pressure sensors could be significantly affected by not only the environmental temperature but also the residual stress due to fabrication and packing processes.Finally,a new method to improve the sensitivity of piezoresistive pressure sensor is investigated.The objective is proposed a novel micro-electromechanical system piezoresistive pressure sensor with the four petals membrane combined narrow beams and center boss(PMNBCB)for low pressure measurements.Then,to further improve the sensitivity of the sensor,a series of rectangular grooves are created at the position of the piezoresistors.Results showed that the four petals membrane and rectangular holes can be increased significantly sensor sensitivity.We can conclude that the four petal membrane and introducing rectangular slot are the most suitable deigns for piezoresistive pressure sensor studies.