Low Temperature Zinc Indium Oxide Backplane Development for Flexible OLED Displays in a Manufacturing Pilot Line Environment

ABSTRACTA low temperature amorphous zinc indium oxide (ZIO) thin film transistor (TFT) backplane technology for high information content flexible organic light emitting diode (OLED) displays has been developed. We have fabricated 4.1-in. diagonal OLED backplanes on the Flexible Display Center’s six-inch wafer-scale pilot line using ZIO as the active layer. The ZIO based TFTs exhibited an effective saturation mobility of 18.6 cm2/V-s and a threshold voltage shift of 2.2 Volts or less under positive and negative gate bias DC stress for 10000 seconds. We report on the critical steps in the evolution of the backplane process: the qualification of the low temperature (200°C) ZIO process, the stability of the devices under forward and reverse bias stress, the transfer of the process to flexible plastic substrates, and the fabrication of white organic light emitting diode (OLED) displays.