Novel N2O plasma passivation on polycrystalline silicon thin-film transistors

Abstract

A novel defect passivation process of polycrystalline silicon thin-film transistors (poly-Si TFT's) utilizing nitrous oxide (N2O) plasma was investigated. In terms of the gas flow rate, chamber pressure, and plasma exposure time, the optimum plasma condition has been found to significantly improve the electrical characteristics of poly-Si TFTs. The performance is even better than those passivated with conventional hydrogen plasma. It is believed that the nitrogen radicals from the N2O gas as well as the hydrogen ones from the residual H2O both can diffuse into the gate-oxide/poly-Si interface and the channel poly-Si layer to passivate the defect-states. Furthermore, the gate-oxide leakage current significantly decreases and the oxide breakdown voltage slightly increases after applying N2O-plasma treatment. This novel process is promising for the applications of TFT/liquid crystal displays and TFT/static random access memories.