High-Performance Amorphous Indium–Gallium–Zinc–Oxide Thin-Film Transistor With a Self-Aligned Etch Stopper Patterned by Back-Side UV Exposure

Abstract

We report the fabrication of amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) with a bottom-gate inverted-staggered structure with an etch stopper formed by a self-aligned process using back-side UV exposure. In addition to reduction in process complexity, the gate-to-source capacitance of an a-IGZO TFT is significantly reduced, resulting in fast TFT circuits. The fabricated TFT exhibits a field-effect mobility value of 42.59 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /V·s , a threshold voltage of 6.1 V, and a gate voltage swing of 374 mV/dec. An 11-stage ring oscillator made of TFTs shows a propagation delay time of 56 ns/stage at 25 V.