Application of Taguchi arrays using DOE for optimizing processing and understanding sputtered coated ZnO TFTs

Abstract

This study applies the Taguchi orthogonal array (OA) to improve and optimize the performance of ZnO thin-film transistors (TFT). Radiofrequency (RF) sputtering method was used to deposit the active layer of TFTs. The annealing temperature, environmental conditions, sputter rate, and thin-film thickness were the parameters whose impact on output parameters like mobility was analyzed in the process optimization using design of experiment (DOE). The ZnO TFTs show state-of-the-art performance features, including high saturation mobility (0.83c), high Ion/Ioff ratio (104). The optimal configuration was found to be high annealing temperature 450 °C under N2 atmosphere, low sputter rate. This paper presents a method that can empower the fast optimization of metal oxide TFTs for future developments in the manufacturing process. If a full factorial design had been implemented, 64 tests would have been necessary, however in this work, we have reduced the number of tests to 9 only using Taguchi method.