H and Au diffusion in high mobility a-InGaZnO thin-film transistors via low temperature KrF excimer laser annealing

摘要

We report the fabrication of high mobility amorphous InGaZnO (α-IGZO) thin-film transistors (TFTs) irradiated by a single shot of a 248 nm KrF excimer laser. Very high mobilities (µ) of up to 43.5cm~2/V s were obtained after the low temperature excimer laser annealing (ELA) process. ELA induces high temperatures primarily in the upper layers and maintains very low temperatures of less than 50°C in the substrate region. Scanning Transmission Electron micrographs show no laser induced damage and clear interfaces after the laser irradiation. In addition, several characterization studies were performed to determine the µ improvement mechanism. The analysis of Secondary Ion Mass Spectrometry and X-ray Photoelectron Spectroscopy suggests incorporation of H mainly from the hybrid passivation layer into the channel. Moreover, Energy-dispersive X-ray Spectroscopy results show that Au diffused into the channel after ELA. Both KrF ELA-induced H and Au diffusion contributed to the higher µ. These results demonstrate that ELA can greatly enhance the electrical properties of a-IGZO TFTs for promising applications in large area, transparent, and flexible electronics.