Impacts of the Thermal Recovery Process on In–Ga–Zn–O (IGZO) TFTs

In this letter, we investigate the impact of the thermal recovery (annealing) process on the electrical characteristics and the stability of IGZO TFTs in terms of: 1) vertical/lateral diffusion of Ti atoms into the IGZO channel region from the source/drain electrode and 2) recovery or local rearrangement of ions in IGZO. Although low thermal recovery temperatures <;300 °C are required to avoid the Ti diffusion that degrades IGZO TFT electrical characteristics, the TFT devices fabricated below 300 °C becomes very unstable in gate/drain electrical-stresses as a tradeoff.