THE EFFECTS OF FLUORINE PASSIVATION ON POLYSILICON THIN-FILM TRANSISTORS

The fluorine implantation on polysilicon was found to improve the characteristics of polysilicon thin-film transistors (TFT's). The fluorine passivates the trap states within the polysilicon channel. As compared with the H-2-plasma passivation, the fluorine implantation passivates more uniformly both the band tail-states and midgap deep-state, while the H-2-plasma treatment is more effective to passivate deep states than tail states. A fluorine-implanted device can be further improved its performance if an H-2-plasma treatment is applied. In contrast to the H-2-plasma passivation, the fluorine passivation improves the device hot-carrier immunity. Combining the fluorine passivation and H-2-plasma passivation, a high performance TFT with a high hot-carrier immunity can be obtained.