(A) study of improving the reliability of low temperature dual-gate In-Ga-Zn-O TFTs for active matrix monolithic micro LED display

Abstract

In this work, we investigate the method to make high reliable a-IGZO dual-gate bottom-contact structured thin-film transistors (TFTs) for active matrix monolithic micro LED display using organic inter layer dielectric (ILD). Micro LED is treated as next generation display due to their low power consumption, high brightness, excellent stability, and so on. But, its cost is expensive for mass production. Organic ILD makes cost cheaper with fast process speed and low process temperature. However, TFTs made at low temperatures have a disadvantage of low stability due to insufficient defect curing during post annealing process. Therefore, a method of improving stability through passivation of these insufficiently curried defects was studied. As the deposition temperature of Al$_2$O$_3$ insulator layer in contact with the a-IGZO active layer is changed, the amount of hydrogen in the film is adjusted, and accordingly, factor that affects the improvement of PBTS stability is verified even at a 230 ℃. It also confirmed the effect of the degree of exposure of a-IGZO layer to light on NBIS stability. As a result, highly reliable a-IGZO TFT and micro LED array that operate well according to the applied voltage was manufactured even at a 230 ℃