High Performance oxide thin-film transistor for large-screen, high-resolution organic light-emitting diode display

This paper describes our recent progress in fabrication technologies for back-channel-etched (BCE) and self-aligned (SA) oxide thin-film transistors (TFTs). These structures enable shorter channel length and smaller parasitic capacitance than conventional etching-stopper (ES) structures, and are effective to realize large-screen, high-resolution organic light-emitting diode (OLED) displays that require high speed driving TFTs. It is important to reduce the damage to the back-channel region during the TFT fabrication process to achieve BCE oxide TFTs with good switching behavior. We have developed high-mobility BCE In-W-Zn-O (IWZO) TFTs using a bi-layer structure. Furthermore, SA In-Ga-Zn-O (IGZO) oxide TFTs have been developed using backside excimer laser irradiation, which selectively reduces the resistance of the IGZO film using a gate electrode as a mask. We present the properties of the IGZO film irradiated with excimer laser light and demonstrate that the source and drain regions can be formed in accordance with the position of the gate electrode.