PROCESS-RELATED INSTABILITY MECHANISMS FOR THE HYOROGENATED AMORPHOUS SILICON THIN FILM TRANSISTORS

摘要

Thin film transistors (TFTs) with various hydrogen concentrations in the amorphous silicon (a-Si:H) films and different silicon nitrides (SiNx) gate compositions have been stressed with dc bias to realize the process-related device reliability. For the positive gate bias stress, the instability phenomena mainly come from the electron trapping in the SiNx On the other hand, for the negative gate bias stress, the hydrogen-enhanced state creation in the a-Si:H films due to the defect pool effect will be offset by the hole trapping in the SiNx. Consequently, the reliability of the TFTs was improved by using the SiNx gates with less trap sites and reducing the hydrogen concentration in the a-Si:H films.