40‐4: Invited Paper: Self‐Aligned Top‐Gate Amorphous In‐Ga‐Zn‐O Thin‐Film Transistors with Hafnium‐Induced Source/Drain Regions

We demonstrated self‐aligned top‐gate (SATG) amorphous indium‐gallium‐zinc oxide (a‐IGZO) thin‐film transistor (TFT) where the source/drain (S/D) regions were induced into a low resistance state by first coating a thin hafnium (Hf) film and then performing thermal annealing in oxygen. The experimental results show that the sheet resistance of the Hf‐treated a‐IGZO layer can be as low as 408 Ω/□. The a‐IGZO TFT fabricated in the proposed processes shows excellent electrical performances, such as a field effect mobility of 16.6 cm 2 /V·s, a subthreshold swing of 0.20 V/dec, an on/off current ratio over 10 9 , and high stability against electrical stress.