用于恶劣环境的耐高温压力传感器

摘要

In order to solve the pressure measurement problem in harsh environments, such as high temperature above 200 ℃, a special piezoresistive pressure sensor with the ranges of 0～120 kPa is developed based on the Micro Electro-mechanical System(MEMS) and Separation by Implantation of Oxygen(SIMOX) technology. The piezoresistive pressure sensor chip consists of a silicon substrate, a thin silicon dioxide layer, an optimized boron ion implantation layer photolitho graphically patterned on a Wheatstone bridge configuration, a stress matching layer with silicon nitride, a Ti-Pt-Au beam lead layer for bonding gold wires, and a cavity fabricated by the wet etching. A special buried silicon dioxide layer with a thickness of 367 nm is fabricated by the SIMOX technology with the oxygen ion dose of 1.4×1018/cm2 and an implantation energy of 200 keV. The buried SiO2 layer is used to isolate the upper measuring circuit layer from the silicon substrate to avoid the leak-current influence, so the fabricated sensor chip can be used in a high temperature above 200 ℃. In order to improve the stability in the wide temperature range, the temperature compensation methods are studied and carried out, so the Temperature Coefficient of Sensitivity(TCS) and Temperature Coefficient of Offset(TCO) of the compensated sensor are easily obtained to be less than 1×10-4/℃·FS. The calibration results show that the developed high temperature pressure sensor has good performances under 200 ℃ for alinearity error of 0.12%FS, a repeatability error of 0.1%FS, a hysteresis error of 0.12%FS, and the sensor's accuracy of 0.197%FS. Which shows it is able to meet the requirements of modern industry, such as oilcans, wind tunnels, mobiles,petrochemical industry,etc..%为了解决如高温200℃等恶劣环境下的压力测量问题,基于微机电系统(MEMS)和高能氧离子注入(SIMOX)技术,研制了一种量程为0～120 kPa的压阻式压力传感器.该传感器芯片由硅基底、薄层二氧化硅、惠斯登电桥结构的硼离子注入层、氮化硅应力匹配层、钛-铂-金梁式引线层和由湿法刻蚀形成的空腔组成.在氧剂量1.4×1018/cm2和注入能量200 keV条件下,由高能氧离子注入技术形成厚度为367 nm的埋层二氧化硅层,从而将上部测量电路层和硅基底隔离开,解决了漏电流问题,使得传感器芯片可以在高温200 ℃以上的环境下使用.为了提高传感器在宽温度范围内的稳定性,对温度补偿工艺进行了研究,补偿后的传感器灵敏度温度系数和零位温度系数很容易控制在1×10-4/℃·FS.实验标定结果表明:在200 ℃下,研发的耐高温压力传感器具有很好的工作性能,其线性度误差达0.12%FS、重复性误差为0.1%FS、迟滞误差为0.12%FS,精度达0.197%FS,满足油井、风洞、汽车和石化工业等现代工业的应用需求.