Design For High-temperature Polysilicon Pressure Sensors

The study presented in this thesis is on manufaching technology of pressure sensors for electrical control. The thesis consists of three parts.Part One (introduction to Chapter 1)gives an overall review on the research and development in the related fields.Part Two (Chapter 2) focuses on the sdudy of a design technique for high-temperature polysilicon pressure sensors. Part Three (conclusion)discuss the result of measurement of sensors.In part Two,firstly, the principles of polysilicon pressure sensors are discussed .Analysis was made what the affect to the sensitivity of sensors with the piezoresistive effect of polysilicon and the stress of mechanical structures of sensing diaphragms. For improve the sensitivity of sensors, A novel diaphragm structure with double-bossed and the longitudinal piezoresistance coefficients of polysilicon is discovered .Secondly the procedure of parameters design are described detailly. Based on,the photosensitive masks of sensor chip are designed. In the project ,take the Si3N4 film of LPCVD instead of Si02 in the anisotropic etching technology .which ensured the performance of sensors to meet the needs of applications for electrical controls.The devices are fabricated by IC processes and the MEMS technology,the sensitivity of the sensors is measured to be 70mV/100Kpa under a driving of lmAdc,the linearity best then 0.10%FS. The overload capability over 10 times. The results proved the design project is advanced.