61.1: Invited Paper : ZnO Thin Film Transistors and Circuits on Flexible Polymeric Substrates by Low‐Temperature PEALD

We report using a novel, weak oxidant, plasma‐enhanced atomic layer deposition (PEALD) process at 200 °C to fabricate stable, high mobility ZnO thin film transistors (TFTs) and fast circuits on glass and polyimide substrates. Weak oxidant PEALD provides a simple, fast deposition process that results in uniform, conformai semiconductor and dielectric layers and enhancement‐mode MOSFETs from uncompensated films. Highly conformai PEALD Al 2 O 3 layers provide a high yield dielectric on rough plastic substrates for both PEALD ZnO TFTs and cross‐overs. Our PEALD ZnO TFTs have field‐effect mobility of >20 cm 2 /V·s on polyimide substrates with excellent bias stress stability. TFTs biased continuously for 40,000s showed <50 mV threshold voltage shift. We also report fast PEALD ZnO circuits on polyimide substrates with propagation delay <20 ns/stage for V DD = 18 V.