LTPS TFT Process on Polyimide Substrate for Flexible AMOLED

For conventional active-matrix organic light-emitting diode (AMOLED) flat panel displays, low temperature poly-silicon thin-film transistor (LTPS TFT) on rigid glass substrate process has already been well established. However, this technology cannot be applied directly on polyimide (PI) substrate for flexible display. This is because PI has the different coefficient of thermal expansion (CTE) from the glass, which will result in PI film peeling-off and/or warpage issues under conventional LTPS-TFT process technology. In this paper, a process flow of LTPS TFT on PI substrate for flexible display application was discussed. A flexible display demo system was successfully made by optimizing the LTPS TFT process.