Effect of Femtosecond Laser Postannealing on a-IGZO Thin-Film Transistors

Abstract

In this study, the effects of femtosecond laser postannealingwere experimentally confirmed by applying it to amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistor (TFT) with enhanced electrical characteristics. We confirmed that a-IGZO TFTs fabricated by applying femtosecond laser annealing for 50 and 100 s improved more than as-deposited a-IGZO TFTs before annealing. However, a-IGZOTFTs irradiated formore than 150 s degraded in overall performance compared with the as-deposited a-IGZO TFTs. The result of the X-ray photoelectron spectroscopy measurement of the O1s peak on the a-IGZO thin-film indicated that the O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> /O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">total</sub> value dropped to approximately 44.3%, and the O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">total</sub> value increased to approximately 17.6% when the a-IGZO thin film was irradiated for 150 s. As a result, oxygen vacancies remained without sufficient recovery of the metal-oxygen bond, and as the electron concentration increased, the conductivity increased, and the performance of the TFT decreased due to an increase in leakage current. A resistive load inverter was fabricated by connectinga TFT irradiatedwith the femtosecond laser at the best-performing time of approximately 100 s. The result of measuring the reversal characteristics confirmed a large inversion at the rising and falling edges.