Self-Aligned Top-Gate Oxide Thin-Film Transistor Formed by Aluminum Reaction Method

Abstract

We developed a novel highly reliable self-aligned top-gate oxide semiconductor thin-film transistor (TFT) formed by the aluminum (Al) reaction method. In this method, Al diffusion into the oxide semiconductor was observed. The low sheet resistivity of the source/drain regions was attributed to Al working as a donor in the oxide semiconductor. The TFTs with 4 µm channel length exhibited a field-effect mobility of 9.8 cm2 V-1 s-1, a threshold voltage of -1.5 V, and a subthreshold swing of 0.22 V/decade. Highly reliable TFTs were obtained after 300 °C annealing without increasing the sheet resistivity of source/drain regions.