CMOS微环境pH传感芯片研究

基于离子敏感场效应晶体管(ISFET)基本结构及其电学特性,提出了一种应用标准CMOS工艺实现的多层浮栅结构pH-ISFET.利用CMOS标准工艺中LPCVD淀积的Si3N4钝化层作为氢离子敏感层,pad工艺形成微区域独立传感窗口.片上集成100 μm×100 μm电极提供参考电位,消除了外加参考电位引起的溶液电压分布不均的现象.缓冲液从pH值1-13范围内对ISFET进行了测量,器件阈值电压随溶液pH值变化的平均灵敏度为44 mV/pH,线性度在10%范围内.本结构可用于生物微环境pH值集成传感芯片设计中.

Research of CMOS microenvironment pH Sensor

Based on the Ion-Sensitive Field Effect Transistor structure and electro-characteristic. A pH-ISFET has a multi-layer floating electrode structure realized in standard CMOS technology is presented in the paper. The pH-ISFET uses silicon nitride passivation layer deposited through LPCVD as a pH sensitive material. The pad process forms independent sensing area in micro-size. An on-chip integrated 100um by 100um electrode offers reference voltage, which can eliminate asymmetric voltage distribution induced by external voltage. The ISFET sensor has an average sensitivity of 44mV/pH between pH 1 and pH 13, its linearity is in the range of 10 percent. This structure can be used to design integrated pH sensor on chip, which suitable for biological microenvironment measurement.