Reliability Study of Self-Aligned Top-Gated a-IGZO TFTs by N2 and N₂O Plasma Treatment

The study investigates the amorphous InGaZnO (a-IGZO) self-aligned top-gate thin-film transistor (TFT) using N<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> and N<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O plasma treatments on the IGZO surface, respectively. The trade-off in reliability between positive bias stress (PBS) and negative bias illumination stress (NBIS) are analyzed. The N<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> plasma treatment for TFTs results in a slightly positive threshold voltage (V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf>) shift under PBS than N<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O plasma treatment. However, the device with N<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> plasma treatment has more negative V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> shift under NBIS due to low bond dissociation energy of Ga-N bonds.