ZnO thin film transistors by low temperature deposition plasma-enhanced atomic layer deposition in a showerhead reactor

Oxide semiconductor TFTs are of interest where low-cost, high mobility, and compatibility with flexible substrates is required. We have previously demonstrated high quality thin-film transistors (TFTs) using ZnO and Al₂O₃ deposited at low temperature (200°C) by weak oxidant, plasma-enhanced atomic layer deposition (PEALD) using a reactor utilizing a pump and purge mode of operation [1]. We also reported the use of thin, weak oxidant, PEALD Al₂O₃ films as gate insulator for scaled III-V MOSFETs [2]. In this work, we report TFTs fabricated using ZnO and Al₂O₃ deposited in a novel weak oxidant PEALD reactor using a showerhead to dispense the reactant gases and an integrated load-lock.