基于重掺杂的谐振式传感器频率温度系数补偿研究

MEMS谐振式传感器具有精度高、准数字输出、抗干扰能力强等特点,高精度压力传感器、应力传感器等多采用谐振式工作原理.频率温度系数补偿是实现高精度谐振式传感器的关键技术.通过实验研究了利用重掺杂改善硅频率温度系数的技术.实验表明:P型掺杂浓度达到7 × 1019/cm3 时,〈110〉晶向频率温度系数降低到-11. 68 ×10-6/K;N型掺杂浓度达到6 ×1019/cm3 时,〈100〉晶向谐振频率是温度的二次函数,在80℃左右频率温度系数有过零点.首次实验演示了利用低功耗加热控制结合N型重掺杂,当环境温度由30℃变化到40℃时,谐振频率温度漂移仅为1. 13 ×10-7/℃.利用该技术可实现超高温度稳定性的谐振式传感器.

Study on temperature coefficient compensation of frequency of resonant sensor based on degenerate doping

MEMS resonant sensor has features of high precision,quasi digital output and strong anti-interference. High precision pressure sensors and strain sensors most adopt resonant working principle. The compensation of temperature coefficient of frequency( TCF)is one of the key issues to realize high precision resonant sensors. Compensation of silicon temperature coefficient of frequency with degenerate doping has been studied by experiments. lt is shown by experiments that temperature coefficient of resonant frequency in〈110〉orientation decreased to -11. 68 ×10-6/K by 7 ×1019/cm3 P+ doping;resonant frequency in〈100〉orientation is quadratic function of temperature after 6 × 1019/cm3 N+ doping,temperature coefficient of resonant frequency crosses zero point at about 80℃. lt has been shown for the first time that the resonant frequency temperature drift is only 1. 13 ×10 -7 when the ambient temperature changes from 30℃ to 40℃ with low power consumption heating control combined with N type degenerate doping. Resonant sensors with ultra high temperature stability can be developed with the technique.