Research On Design,Fabrication And Mass Calibration And Testing Of Micro Silicon Pressure Sensors

As an important kind of sensors,MEMS pressure sensor utilizing piezoresistive effect have benefits of small size,low power and low price,and it has been widely used in many fields such as industrial control,automobile electronics,comsumer electronics,medical electronics,aviation and aerospace.This dissertation took a thorough research on the pressure sensor design,fabrication,signal conditioning and testing,targeting a silicon piezoresistive pressure sensor manufactured by bulk micromachining and surface micromachining.Firstly,aiming to the limitations of the traditional shield layer of pressure sensors,a pressure sensor with a shield layer formed by ion implantation was proposed.The pressure sensor was based on single crystal silicon piezoresistive effect,and it was fabricated using bulk micromachining technology.The key parameters of the structure and process were computated by co-design of structure and process.Simulation and experiment results indicated that the pressure sensor showed some significant improvements in thermal stability and electrical field stability compared to a traditional one.Secondly,a pressure sensor with a low stress nitride membrane was proposed.It was based on polysilicon piezoresistive effect and surface micromachining technology.Low stress nitride membrane could prevent the current leaking to the substrate.Hence,the temperature drift of the pressure sensor was reduced.Testing result showed that the sensitivity was up to 0.0137mV/V/hPa,and the sensitivity drift was-0.086%FS/°C which was much smaller than traditional MEMS pressure sensor.Finally,a mass calibration and testing system was proposed.According to the functions,the system was devided into six modules.The system software was made up by three layers,those were user interface layer,application layer and device drive layer.This architecher had benefits of expansion and maintance.Meanwhile,the productivity and accuracy were enhanced.The mass calibration and testing system was verified by production producing.More than 1060 pressure sensors could be calibrated and tested in one day,and the yield was up to 97.3%.