Effects of Ultra-Violet Wet Annealing on Electrical Performance of Back Channel Etching Cu/Mo/IGZO 4 Mask Thin Film Transistor

Abstract

The effects of various post annealing treatments for back channel etched InGaZnO thin film transistors were compared. A novel post wet annealing method was proposed to enhance the electrical properties of IGZO TFTs with a copper/molybdenum source/drain using ultraviolet illumination. Compared to previously reported post wet/dry treatments, the new post wet annealing was effective in increasing the on/off current (i(on)/i(off)) ratios and lowering the threshold voltages (V-th) of the oxide TFTs. The treatment time was less than 30 min, and the wet chemical temperature was below 60 degrees C. The i(on)/i(off) ratios of the transistors were enhanced two fold, and the Vth values shifted in the negative direction compared to the values resulting from thermal annealing at 300 degrees C for 1 hour. It was concluded that UV wet annealing is a very effective method in enhancing the electrical properties of IGZO transistors fabricated on flexible substrates.