Employ Present Five Masks Amorphous Silicon Thin-Film Transistor Design and Process Flow to Realize 5-in. InGaZnO Active-Matrix Liquid Crystal Display with Improved Stress Stability

The present five masks bottom gate and staggered amorphous silicon (a-Si) thin-film transistor (TFT) process flow is not suitable for indium–gallium–zinc-oxide (IGZO) TFT because of its vulnerability to post etching process during the source/drain pattern. Bottom gate and coplanar IGZO TFTs were made feasible through the reverse of second (channel layer) and third (source/drain electrodes) masks process flow to avoid etching damage problem. Besides, the post IGZO nitrous oxygen (N 2 O) plasma treatment was employed to improve the stress instability. On the basis of secondary ion mass spectrometry (SIMS) and X-ray spectroscopy (XPS) results, it is believed that the post N 2 O plasma treatment passivates the interface states and converts the inhomogeneous and low quality IGZO to the homogeneous and high quality IGZO. In the end, a 5-in. IGZO active-matrix liquid crystal display was demonstrated via five masks bottom gate and coplanar TFT configuration.