基于标准CMOS工艺的pH值传感器

基于传统离子敏感器件的敏感模型,建立了与CMOS工艺兼容的以钝化层氮化硅作为敏感膜的MFGFET(multi-floating gate FET)多层浮栅晶体管结构阈值电压模型.采用上华0.6μm CMOS标准工艺,设计了一种与CMOS工艺兼容的pH值传感器.片上控制电路使MFGFET器件源漏电压和源漏电流恒定,器件工作在一个稳定的状态.采用离子敏MFGFET和参考MFGFET差分拓扑结构,减少了测量电路的固定模式噪声.器件溶液实测pH值在1～13范围内,器件的平均灵敏度为35.8mV/pH.

pH Sensor Realized with Standard CMOS Process

Based on the conventional sensitive model of an ion-sensitive structure,a threshold voltage model that uses a silicon nitride passivation layer as the sensitive membrane with a multi-floating gate field effect structure has been built.A pH sensor compatible with CMOS is designed according to the 0.6μm CMOS standard process offered by Shanghua.An integrated control circuit keeps the source drain voltage and source drain current of the MFGFET structure in a steady state.Pattern mode noise in the circuit is reduced through a differential output between the ion-sensitive MFGFET and a reference MFGFET.The test result shows the pH sensor has an average sensitivity of 35.8mV/pH from pH 1 to pH 13.