29.5: Reliability Enhancement of an Indium‐Gallium‐Zinc Oxide Thin‐Film Transistor by Pre‐Fluorination Non‐Oxidizing Annealing

Techniques of overcoming issues of device instability and negative turn‐on voltage of an fluorinated indium‐gallium‐zinc oxide (IGZO) thin‐film transistor have been investigated. Such improvement correlates with the annihilation of oxygen‐related defects in the fluorinated channels. However, further extension of the fluorination time has been found to lead to degradation of some device characteristics. An alternative process has been proposed, involving the addition of a non‐oxidizing anneal before the fluorination treatment. Consistenet with the higher fluorine content in the IGZO layer revealed using secondary ion‐mass spectrometry, more positive shift of the turn‐on voltage and improvement in reliability have been obtained, without the TFT suffering from degradation in other device characteristics.