Metal oxide thin-film transistors (TFTs) have attracted considerable attention for use in next-generation high-definition and large-area flat-panel displays (FPDs) owing to their excellent electrical properties such as high mobility (>10 cm²/Vs), large-area uniformity, and compatibility with low-temperature process. An InGaZnOx (IGZO) is widely employed as a channel material of oxide TFT. Although an IGZO film can be deposited by sputtering without an intentional substrate heating, an IGZO TFT requires a post-annealing around 300°C due to the recovery defective states induced during the sputtering process. A post-annealing required for improving TFT characteristics and reliability is often named as “activation annealing”. The activation annealing around 300°C limits the fabrication of oxide TFTs on flexible substrates. Several activation methods for oxide semiconductor, such as simultaneous UV and thermal annealing, electrical assisted thermal annealing, and high-pressure annealing, have been proposed to reduce annealing temperature at ~150°C. Another approach is an improving film quality of the sputtered IGZO.

In this presentation, a new method to achieve high quality sputtered IGZO film will be presented. Proposed deposition method reduced density of states near conduction band, and could reduce an activation annealing temperature to 150°C. Detail mechanism to achieve low-temperature activation of IGZO TFT will be discussed.