Highly ordered crystalline InGaZnO (c-IGZO) TFTs have been demonstrated in subsequent processes above 550 °C compatible with memory applications. Notably, c-IGZO featured strong immunity to high temperature and hydrogen-containing processes unlike amorphous IGZO (a-IGZO) where agglomeration occurs. The c-IGZO TFTs with optimized process in this study show a higher on-current (Ion) at a similar Vth of −1 V, and Ioff of 1.82×10−18 A/μm compared with a-IGZO TFTs. In addition, striking enhancement in the short channel margin and Vth stability over a-IGZO was achieved. With thin gate-oxide (50 Å), the improved device performance was realized such as S.S. × 0.41, DIBL × 0.18, and Ion× 76.5 compared with a-IGZO TFT at Tox 100 Å.