Highly reliable a-InGaZnO thin film transistors with new SiNx gate insulators

We fabricated highly reliable a-InGaZnO thin film transistors (TFTs) with new silicon nitride (SiN_x) gate insulator (GI) fabricated at low temperature (150°C). This new SiN_x layer has low hydrogen content which is controlled by the source gases. Hydrogen gas flow rate ratio to SiF₄ was changed as 0%, 1%, and 8%, but the bias-stress-induced threshold voltage instabilities on the three kinds of TFTs kept quite low value. We found that the improvement for threshold voltage instabilities was not due to the effect of the hydrogen content. It is assumed that fluorine in the film, which originates in the source gas, has possibility to improve the interface between the channel and GI.