A novel process-compatible fluorination technique with electrical characteristic improvements of poly-Si TFTs

A process-compatible fluorine passivation technique of poly-Si thin-film transistors (TFTs) was demonstrated by employing a novel CF₄ plasma treatment. Introducing fluorine atoms into poly-Si films can effectively passivate the trap states near the SiO₂/poly-Si interface. With fluorine incorporation, the electrical characteristics of poly-Si TFTs can be significantly improved including a steeper subthreshold slope, smaller threshold voltage, lower leakage current, higher field-effect mobility, and better on/off current ratio. Furthermore, the CF₄ plasma treatment also improves the reliability of poly-Si TFTs with respect to hot-carrier stress, which is due to the formation of strong Si-F bonds.