Research Of Intergrated Biosensor Chip Based On Field-effect Transistors

Integrated potentiometric biosensor chip with pH-ISFET sensor is developed, and some related theories and key technologies with Bio-System on Chip (SOC) are studied.A novel floating-gate ISFET structure is developed together with readout interface. A Ta₂O₅-gate ISFET/PTFE-gate REFET pair is realized together with a Pt metal electrode (quasi reference electrode, QRE) on a single chip.Physical-chemical behavior of Electrolyte/insulator/semiconductor system (EIS) is analyzed base on the site-binding model, and a SPICE compatible macro-model of the Ta₂O₅-gate ISFET is developed. The model is friendly used and allows more accurate simulation of the device operating with the on-chip readout interface.The chip is manufactured with standard CMOS technology (Chartered Semiconductor, Singapore). A novel mold is developed for post process, and the sensor chip is fabricated with MEMS technology.The influence of deposition conditions, such as substrate temperature, deposition pressure, on Ta₂O₅ sensitive characteristics are studied systematically. The sensing film is achieved at low substrate temperature (300℃) with high sensitivity (54.5mV/pH), rapid response (0.2s), excellent stability (0.03mV/h) and reproducibility, which is compatible with the integrated sensor chip.A monolithic chip is achieved with high sensitivity and excellent stability, which proves the compatibility of monolithic sensor chip. The research paves the way for advanced digital intelligent and miniaturized sensor systems.