Physical mechanism of source and drain resistance reduction for high-performance short-channel InGaZnO thin-film transistors

We systematically study the mechanism of source and drain parasitic resistance reduction in amorphous InGaZnO thin-film transistors. Hall measurement shows that parasitic resistance is reduced by the increase in carrier density regardless of the source and drain processes. The results of photoluminescence, high-angle annular dark field scanning transmission electron microscope (HAADF-STEM), electron energy-loss spectroscopy (EELS), and X-ray photoelectron spectroscopy (XPS) analyses indicate that the fluctuation of In concentration at the InGaZnO surface is responsible for increase in carrier density. A top-gate InGaZnO transistor fabricated with a source drain resistance reduction process shows good short-channel immunity. The short-channel InGaZnO thin-film transistor with reduced source drain resistance is promising as the high-density back-end-of-line transistor in Si LSI. (C) 2015 The Japan Society of Applied Physics