Investigation into sand mura effects of a-IGZO TFT LCDs

Abstract The reliability of liquid crystal display (LCD) panels based on amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) is investigated. It is revealed that the a-IGZO TFT LCDs also have sand mura issue at high operation temperature. Analysis shows that the sand mura is caused by the positive V th shift of the a-IGZO TFTs. To suppress the V th shift, fabrication process of the a-IGZO TFTs is optimized with a-IGZO channel layer annealed at 300 °C and etch-stop layer deposited at 250 °C. The process optimization lessens the absorbed and non-bonded oxygen atoms in the a-IGZO channel layer and desorbed water molecules on the back channel surface. The results show that the V th shift is significantly alleviated and the sand mura is thus effectively minimized with the optimized process.