4.3: Invited Paper: High Mobility Oxide TFT for Large Area High Resolution AMOLED

The adoption of bi‐layered etch stop layer (BiESL) for oxide thin film transistor with high carrier mobility was proposed for the application to the large area high resolution AMOLED. A novel bi‐layered etch stop structure composed of Al 2 O 3 /SiO 2 , in which thin and dense Al 2 O 3 film prepared by atomic layer deposition was deposited on the PECVD SiO 2 layer. High mobility of In‐Ga‐Zn‐O TFT with the proposed BiESL showed no significant change in turn‐on voltage, even without passivation film. The field‐effect saturation mobility and sub‐threshold swing were measured as 29 cm 2 /V.s and 0.21 V/dec, respectively. Hydrogen doping during the PECVD SiN x passivation process can be effectively prevented by the introduction of Al 2 O 3 . Furthermore organic planarization film can be coated directly on top of the TFT array without causing any significant degradation of TFT performance.