Electrical Performance and Reliability Improvement of Amorphous-Indium-Gallium-Zinc-Oxide Thin-Film Transistors with HfO(2) Gate Dielectrics by CF(4) Plasma Treatment

In this work, amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) with a HfO(2) gate insulator and CF(4) plasma treatment was demonstrated for the first time. Through the plasma treatment, both the electrical performance and reliability of the a-IGZO TFT with HfO(2) gate dielectric were improved. The carrier mobility significantly increased by 80.8%, from 30.2 cm(2)/V∙s (without treatment) to 54.6 cm(2)/V∙s (with CF(4) plasma treatment), which is due to the incorporated fluorine not only providing an extra electron to the IGZO, but also passivating the interface trap density. In addition, the reliability of the a-IGZO TFT with HfO(2) gate dielectric has also been improved by the CF(4) plasma treatment. By applying the CF(4) plasma treatment to the a-IGZO TFT, the hysteresis effect of the device has been improved and the device’s immunity against moisture from the ambient atmosphere has been enhanced. It is believed that the CF(4) plasma treatment not only significantly improves the electrical performance of a-IGZO TFT with HfO(2) gate dielectric, but also enhances the device’s reliability.