Effect of back-channel plasma etching on the leakage current of a-Si : H thin film transistors

Abstract

The effects of back-channel plasma etching conditions and the amount of HCl and plasma power on the leakage current of a-Si:H thin-film transistors (TFTs) were studied. Atomic force microscopy (AFM) and secondary ion mass spectrometry (SIMS) analyses were performed to determine the optimal etching conditions which reduce the leakage current at the back channel. Etching with a HCl-rich gas mixture was found to be effective to reduce the leakage current and chlorine ions were believed to affect the back-channel surface characteristics and exhibit acceptor-like behavior in the lower subthreshold region. Chlorine is believed to suppress the electron generation in the back-channel region and trap electrons that are generated by thermal emission. The back-channel surface roughness was found to have no appreciable effect on the leakage current.